Symposium Introduction
A Theory of Evidence and Well-Founded Belief: Kevin McCain’s Evidentialism and Epistemic Justification
Evidentialism, at its core, is the view that the epistemic rationality of a belief is determined only by the evidence relevant to it. There are two domains wherein evidentialism occasions controversy. The first is whether a belief’s practical and spiritual valences may yield some counterexamples. And so the pragmatist may hold that it is better for some practical reason to believe beyond one’s evidence. Or the fideist may say that faith is a theological virtue. Call these the ethics of belief controversies. The second domain of controversy for evidentialism is comprised by the questions of what exactly the theory is. The evidentialist holds, as a theory of justification, that beliefs are rational only if they fit the evidence, and as a theory of belief-management, that one’s beliefs are well-founded when they are based on the evidence they fit. But the conceptual questions loom: What exactly is evidence? What is it to have evidence? What is it for a belief to fit the evidence? And how is it that beliefs are based on evidence? Call this second domain the meta-epistemic controversies for evidentialism.
Kevin McCain’s Evidentialism and Epistemic Justification (2014) is an essay in the meta-epistemic domain of controversy over evidentialism. (For recent work in the ethics of belief domain of controversy, see Syndicate Philosophy’s recent/upcoming symposium on Miriam McCormick’s Believing Against the Evidence.) Within this domain of meta-epistemic controversy, there is a wide variety of views. With the question of what evidence is and what sorts of things can be evidence, there are views, on the one hand, that evidence must be propositional, because evidential support must be in some recognizable inferential form. On the other hand, there are views that evidence may be simply psychological states. This is the propositionalism-psychologism debate. Further, there is the question of whether evidence must be factive or not. In many ways, this debate depends on whether one thinks there is a kind of contradiction in terms to say something of the form, S has evidence for p, but p is false. If it is a contradiction, one must think that evidence is factive. If one does not take that statement to be contradictory, then one must think that evidence is non-factive. This is the factivity of evidence debate.
With the question of what it is to possess evidence, one may be highly inclusive of what can be possessed by a subject, so one’s available evidence could be all of one’s total possible evidence, even the memories from one’s childhood one cannot recall. Alternately, one could be highly exclusive, so one’s available evidence is only what one is currently thinking about. Finally, one could be moderate with the possession requirement and hold that one’s available evidence is either what one is currently thinking or what one can easily remember or bring to mind when thinking about the matter. Views about how beliefs may properly fit the evidence range from the thought that they must be entailed by, made probably by, or are the best explanation for the evidence.
Finally, there is the question of what it is to believe on the basis of one’s evidence. On the one hand, there are doxastic theories, which run that the connection is made by a second-order belief about the evidence and one’s belief. On the other hand, there are causal accounts, which run that subjects believe what they do as the result of their reasons. Call this domain of controversy the basing question.
With the publication of Earl Conee and Richard Feldman’s 1985 essay, “Evidentialism,” and their further developmental work on the subject, questions about the nature of evidence, the fit between beliefs and evidence, and the basing relation between evidence and belief have been central meta-epistemological challenges for evidentialists. Kevin McCain’s book is designed to be a complete theory of epistemic justification in this vein. McCain defends a version of evidentialism that is mentalist and internalist, as he holds that theories of epistemic justification should be bounded by the thoughts driving the New Evil Demon Problem. McCain holds that evidence is either a mental state or a propositional content of one’s psychological state (27). Further, McCain holds that evidence is non-factive, since it seems intuitive that two mentally identical subjects can have the same evidence but one can be fooled by an illusion or have some bad epistemic luck and the other not. McCain defends a moderate view of evidential possession, so one’s dispositionally available thoughts or memories are evidence one possesses, but not all one’s memories.
With regard to the question of how one’s belief can fit the evidence, McCain adopts a modified form of explanationism. He holds that one’s belief that p fits one’s evidence (i.e., one’s non-factive mental states or what one is disposed to recall) when p is either the best explanation for that evidence or is available as a logical consequence of that best explanation (79). And so, if one has the visual impression of two birds and two squirrels on the deck, one would be justified in holding that there are four animals on the deck because it is a logical consequence of the best explanation for the visual impression.
Finally, with regard to the basing question, McCain develops a particular form of the causal theory of the basing relation, one that depends on an interventionist account of causation. McCain holds that his version avoids the challenges of overdetermination and deviant causal chains that plague other versions of the causal theory, and so S’s belief is based on S’s evidence when each piece of S’s evidence is both the direct and actual causes of S’s belief (91). S’s evidence directly causes S’s belief when it causes the belief without detouring through any evidentially irrelevant mental states. In other words, when S’s evidence directly causes S’s belief it doesn’t cause the belief by way of causing some other mental state that in turn causes the belief. When it comes to S’s evidence being an actual cause of S’s belief the rough idea is that S’s actually having that evidence makes a difference to S’s having or not having the belief.
McCain’s program is posited on the distinction between propositional and doxastic justification, and evidentialists have regularly thought that both parts are required for an appropriate theory. We want an account of what it is, first, for a belief to be appropriately supported by evidence (so propositional justification) and also for us to be correctly cognitively moved by those justifying reasons (doxastic justification). That is, we want the evidence not only to favor our beliefs, but for us to hold those beliefs because the evidence favors them. So a complete theory of evidentialism requires this two-part account. In its complete form, McCain’s two-part theory is as follows:
Propositional Justification: Explanationist Epistemic Justification (Ex-EJ)
- Believing p is epistemically justified for S at t if and only if at t S has considered p and:
1) p is part of the best explanation available to S at t for why S has her occurrent non-factive mental states and the non-factive mental states that she is disposed to bring to mind when reflecting on the question of p’s truth
OR
2) p is available to S as a logical consequence of the best explanation available to S in (1
2. Withholding judgment concerning p is epistemically justified for S at t if and only if at t S has considered p and neither believing p nor believing ~p is epistemically justified for S.
Doxastic Justification: Explanationist Well-Foundedness (Ex-WF)
At t, S’s belief that p is well-founded if and only if:
At t,I. 1. Each
I. 1. Each ei ∈ E (the non-factive mental states that constitute S’s evidence) is a direct cause of S’s believing that p
AND
- Each ei ∈ E is an actual cause of S’s believing that p
AND
- It is not the case that intervening to set the values of all direct causes of S’s believing that p, other than the members of E, to 0 will result in S’s not believing that p when every ei ∈ E is held fixed at its actual value (i.e. S’s evidence plays a strong enough causal role in S’s believing that p).S’s belief that
II. S’s belief that p is epistemically justified for S at t by E (i.e. condition (I) of Ex-EJ is satisfied).
III. At t there is no set of S’s evidence, E* such that:
- E is a subset of E*
AND
- p is not epistemically justified for S at t by E*
McCain then turns to making the case that this explanationist evidentialism accommodates the intuitive results of a number of important cases. It can explain why firsthand experience with whether it is a warm day puts one in a better position than another who has only read the paper about the weather (121–22), and it explains why faint memories provide less justification than vivid memories (124). Further, McCain argues, explanationism yields important anti-skeptical consequences. Explanationism provides us with reasons to hold that the truth of our commonsense beliefs about the world is the best explanation (over various skeptical hypotheses) for the relevant features of our sensory experience (216). The viability of McCain’s explanationist evidentialism demonstrates that evidentialism can be fleshed out into a complete theory of epistemic justification. The upshot, then, is explanationist evidentialism promises a variety of important and appealing consequences for several debates central to contemporary epistemology.
5.8.17 |
Response
Infection and Directness in the Interventionist Account of the Basing Relation
fIn Evidentialism and Epistemic Justification, Kevin McCain puts forward a defense of an Evidentialist Explanationist theory of justification. In it, he presents a novel account of the basing relation. Drawing from the interventionist account of causation, he proposes a solution to the problem of deviant causation (widely viewed to be The Problem haunting causal accounts of the basing relation). In this paper, I will raise two problems for McCain’s account: an Infection Problem (in a Global and Local form), and a Direct Cause Problem. The Infection Problem questions whether the account can capture features that undermine doxastic justification. The Direct Cause Problem queries the adequacy of McCain’s account of basing by challenging how evidence could be a direct cause of belief.
The Account
McCain proposes the following account of the basing relation.
IB-R: S’s belief that p at t is based on her evidence, E, if and only if at t:
- Each e1 included in E is a direct cause of S’s believing that p
- Each e1 included in E is an actual cause of S’s believing that p
- It is not the case that intervening to set the values of all direct causes of S’s believing that p, other than the members of E, to 0 will result in S’s not believing that p when every e1 included in E is held fixed at its actual value.[1]
When evaluating whether S’s belief that p (Bp) is well based, the interventionist model will examine all relevant causal influences on the formation of Bp. The set of causal factors can include evidence (non-factive mental states that propositionally justify Bp), other mental states, mental mechanisms, and external influences. An entity, X, is a direct cause of an entity, Y, just in case intervening on X results in a change in value to Y. X is an actual cause of Y just in case varying the actual value of X would vary the actual value of Y, when all other causal factors are held fixed.
In sum, IB-R aims to overcome the traditional problems of deviance and overdetermination by providing a nuanced framework of causal relations. In what follows, I will challenge the adequacy of this account. But first, I’d like to praise its inventiveness. IB-R gives us a way to pull apart the complex web of causes that form our beliefs, and pinpoint exactly where belief formation can go wrong. While I think the interventionist model needs to be fleshed out more carefully, it is a highly promising and novel account of causal basing. The problems with it are, I think, problems with McCain’s Evidentialism, not problems inherent to the interventionist framework.
The Infection Problem
The Infection Problem is a challenge to the sufficiency of IB-R. Here, I will present cases that meet IB-R, but intuitively fail to be doxastically justified. The beliefs fail to be doxastically justified because they suffer from some kind of infection. Local infection occurs when doxastically unjustified beliefs are included in E. I pose a dilemma for McCain and argue he has no acceptable way out. Global infection occurs when cognitive biases (that can only be understood by looking at the agent’s belief forming dispositions counterfactually) undermine doxastic justification. Since these global features are counterfactual and holistic, they cannot be captured by looking only at actual and direct causes.
Local Infection
S’s evidence, E, consists of non-factive mental states which propositionally justify S in believing p. But what if the beliefs in E are not themselves doxastically justified? Let p be “there is a lottery ticket at my feet,” and q be “the lottery is rigged in my favor.” Now consider the case of Ann.
ANN[2]
Suppose Ann is struck by lightning and the effect of the lightning is that a lottery ticket appears at her feet and she forms the belief that p and if p then q. She reasons to the belief that q. She is propositionally justified in believing this, since her non-factive mental states imply it. But, intuitively, her belief that q isn’t doxastically justified, and even if true, her belief that q isn’t knowledge.
Since IB-R does not require that every member of E must itself be doxastically justified, it seems that it gets the wrong verdict in ANN.[3] McCain could give three responses: first, McCain could hold that Ann has a defeater, and so her belief is not propositionally justified. But suppose Ann is a bit stunned and not very reflective. She doesn’t have any background beliefs that directly undermine her justification. She is just happy at her good fortune. Second, McCain could insist that Ann is in fact justified. I think this is implausible, for reasons that McCain himself raises against the doxastic view of the basing relation.[4] If Ann bases her belief on beliefs that are not themselves well-based, then it seems that her belief could not be doxastically justified.
The most promising route, then, seems to be the third option: augment IB-R to require that S’s beliefs must be well-based on well-based based beliefs in order to count as doxastically justified. This seems to be McCain’s approach. After the official formulation, he suggests an extra condition: a belief can only be well based if it is well based on non-factive mental states that are themselves well based.[5]
However, Modified IB-R generates two regresses. The first regress is conceptual. IB-R is an account of the basing relation. Modified IB-R ends up explaining doxastic justification in terms of a relation between a belief and other doxastically justified beliefs. We cannot understand what it is to be doxastically justified without making use of the concept of doxastic justification. This regress might not be vicious: we could reduce any particular relation to a causal relation, though we cannot explain the concept of doxastic justification without making use of the concept in both the explanandum and the explanans. If our aim was to give an account of the nature of basing, then this would be a problem. But if our aim is just to judge whether a particular belief is properly based, then modified IB-R may be sufficient.
The conceptual regress illuminates an additional problem: Modified IB-R is not an instance of the Orthodox View.[6] It does not explain doxastic justification purely in terms of propositional justification. It does not give an account of what it is for a belief to be doxastically justified. Instead, it only explains how doxastic justification is transmitted.
The second regress is a causal one, and it does seem vicious. Modified IB-R requires that for any belief to be well-based, it must stand in a causal relation to E, which includes other beliefs that are themselves well-based. S could not have a doxastically justified belief without having an infinite chain of doxastically justified beliefs. A belief stands in a particular causal relation to a set of evidence, which in turn stands in a particular causal relation to a set of evidence, so on ad infinatum. Modified IB-R seems to rule out foundationalism, since to be well-based, a belief must be based on evidence that is itself well-based. A solution to the causal regress might be coherentism (the preferred view of old school evidentialists). But coherentism does not seem obviously compatible with the interventionist model of basing.
Global Infection
Local infection is not the only way that doxastic justification can be undermined. Doxastic Justification can also be undermined by features of the agent that are not present in E. Turri’s argument against the Orthodox View highlights this point. He presents cases in which the agent is propositionally justified, the evidence causes the belief, but the mechanism that brings about the belief is compromised. The mechanism can be compromised in two ways: (a) the mechanism does not embody formally valid reasoning (PONENS and LACY), or (b) it treats something as evidence when it should not (PROPER and IMPROPER). Turri’s cases rely on this assumption: there is a single mechanism at work in both cases (namely, the mechanism that forms beliefs) and it can function well or function poorly.
McCain avoids Turri’s counterexamples by reifying our belief forming mechanisms into Good Belief Forming Mechanisms and Bad Belief Forming Mechanisms.[7] He posits a rational belief formation mechanism (the one that uses modus ponens, and believing on the evidence) and an irrational belief formation mechanism (the one that engages in wishful thinking, or uses inference rule X). Once we reify belief forming mechanisms in this way, we achieve the intuitive results. We can distinguish PONENS and LACY because they are using different belief forming mechanisms. Believing on the evidence is one belief formation mechanism; wishful thinking is another.
But this is implausible. For psychological and philosophical reasons, wishful thinking and bad inferences are best understood as malfunctions of the same mechanism. It is psychologically implausible to posit that we operate with distinct, non-overlapping belief forming mechanisms, one set of which is “good” and the other set of which is “bad.” The belief forming mechanisms imagined here are causal mechanisms. Even if a mechanism is highly reliable, it is empirically unlikely that it will function perfectly all the time. So even if we can reify the “good” processes and the “bad” processes, it is still implausible to think the good processes will function perfectly. In those cases where the good processes malfunction, Turri’s counterexamples will reemerge. Secondly, we have a disposition to form beliefs. Sometimes that disposition embodies good reasoning. Sometimes it embodies bad reasoning. If we accepted the idea that there are “wishful thinking” mechanisms and “rational” mechanisms, it would be hard to see the output of both mechanisms as beliefs. Consider wishful thinking. We don’t straightforwardly, clear-eyedly, believe something because we want it to be true.[8] Wishful thinking is subtle. It can involve a manipulation of S’s assessment of the exact evidential support that E lends to p. And if this is the case, then it is not clear how IB-R can distinguish wishful basing from well-basing.
To illustrate, consider the Racist Employer, Chet.[9]
CHET
Chet is reviewing applicants for a job, and he forms the belief that Trayvon has a poor file. In fact, Trayvon does have a poor file. Trayvon did not attend a prestigious school, and he has minimal experience. However, had the applicant’s name been Caucasian, Chet would have evaluated the resume differently.[10] Chet is also deeply unaware of his racism. He has no beliefs that he could call to mind that are overtly racist. He is just slogging through a stack of a hundred applicants, trying to find the best candidate.
In this scenario, Chet correctly believes that the Trayvon’s resume is subpar. Considerations of race are playing a role in his belief formation, but not as a premise. His racism is not in the set of beliefs that he has. Rather, his racism is a function of how he interprets his evidence, and which conclusions he draws from that evidence. Even though the racist employer believes p because of evidence that in fact supports his conclusions, he is not reasoning well. It is only when we look at the way his belief forming mechanisms behave in total that we can see the pernicious racism that drives his belief formation. It is only when we examine (counterfactually) how he would reason with Caucasian applicants that we can see his poor reasoning. Chet has a bias that makes him go wrong, and he makes a mistake that corrects the problem. But multiplying mishaps shouldn’t give Chet doxastic justification.
The Direct Problem
One final concern about IB-R. Evidentialism and the interventionist model are not intuitive partners. In what follows, I argue that E could not be a direct cause of S’s belief that p. If IB-R is true and the argument is sound, this argument shows that no belief is or could be well-based. Let E be the set of non-factive mental states that propositionally supports p, and Bp be the belief that p. Let t be the time at which S forms Bp. Let M be the seeming to S that p, and let D be the disposition to form the belief that p when S has M. In order to be a direct cause, a change in the first variable must result in a change in the final variable, when other variables are fixed.[11] Now I will show that fixing D results in E having no causal influence on Bp.
First, E does not immediately cause Bp. If it does cause Bp it does so mediately, through what McCain calls a directed path. This is obvious because one could have evidence that propositionally justifies Bp and yet fail to believe p. This is true for beliefs I haven’t considered. It is true for cases where I am deliberating about whether to form the belief (but haven’t yet formed it). It is true for all inferential beliefs. E is not sufficient to cause Bp.[12] Something else must also be at play. This could be many different things. It could be my attention, it could be my judgment that E supports p, it could be some kind of psychological compulsion within me. But something else is required in order for the belief to come about.
On the interventionist model, this need not be a problem. E could directly cause Bp by directly causing something that directly causes Bp. The result would be a directed path. But E doesn’t directly cause something that directly causes Bp. We can see this because E can support an infinite number of beliefs, but rather than continuously forming infinite sets of beliefs, I am able to deliberate about one matter, and then set it aside. E does not cause me to open deliberation; something else is responsible. I will use the variable X to denote that thing, whatever it is, that causes me to open deliberation. Then, X and E together give rise to M, it seeming to me that p. And M activates D, which causes Bp.
Now that we have this framework in mind, let’s perform interventions. Let V = {E, X, S, D}. Fix X, M and D at 0. Given what we said above, intervening on E will have no effect on Bp. So E is not a direct cause of Bp. Now suppose we fix D and M at 1. Then it doesn’t matter how we intervene on E, Bp will obtain. Why? Because D and M are necessary and sufficient for causing Bp. It is directly analogous to McCain’s spark example:
[The faulty wiring] is not a direct cause of [the fire] because we cannot hold [the other variables] fixed at some values and manipulate the value of [the fire] by changing the value of [the faulty wiring]. . . . The only way that the short-circuiting of the electrical wiring can affect whether or not there is a fire in this case is by affecting whether there is a spark in the room. Once the presence or absence of the spark is held fixed, manipulating whether the electrical wiring short circuits cannot change whether the fire occurs. So the short circuiting of the electrical wiring is not a direct cause of the fire.[13]
Similarly, once we hold fixed that it seems to S that p, and that S has the disposition to form Bp on the basis of this seeming, the result (Bp) is determined. So E is not a direct cause of Bp.
I can see a way around the Direct Problem, but not if we hold on to McCain’s evidentialism. A reliabilist could say that a belief is well-based if it is caused by a reliable belief forming mechanism. It would effectively remove the extra step of what supplied by X above. Once we remove X from our intervention, we can show that the belief forming mechanisms are the direct cause of the belief. The interventionist model seems to be a very promising strategy to tackle deviant causation. But I’m not sure that IB-R is the best version of it.
[Conclusion
McCain presents a thorough, interesting, and rich discussion of the evidentialism and the basing relation. Despite his interesting proposal, the basing relation is a stubborn problem. Infection and Directness problems prevent it from being a satisfying account.
Works Cited
Bennett, Jonathan. (1990). “Why Is Belief Involuntary?” Analysis 50 (2).
Evans, Ian. (2013). “The Problem of the Basing Relation.” Synthese 190: 2943–47.
Davidson, Donald. (1963). “Actions, Reasons, and Causes.” Journal of Philosophy 60 (23): 685–700.
Flowerree, A. K. (2016). “Agency of Belief and Intention.” Synthese: Special Issue on Doxastic Agency, Heinrich Wansing and Andrea Kruse, ed.
Hieronymi, Pamela. (2009). “Believing at Will.” Canadian Journal of Philosophy 39: 149–87.
Lehrer, Keith. (1971). “How Reasons Give Us Knowledge, or the Case of the Gypsy Lawyer.” Journal of Philosophy 68 (10): 311–13.
McCain, Kevin. (2014). Evidentialism and Epistemic Justification. Routledge University Press.
Street, Sharon. (2011). “Evolution and the Normativity of Epistemic Reasons.” Canadian Journal of Philosophy 35, on Belief and Agency, ed. David Hunter, 2011, 213–48.
Shah, Nishi. (2003). “How Truth Governs Belief.” Philosophical Review 112, no. 4: 447–82.
Shah, Nishi, and J. David Velleman. (2005). “Doxastic Deliberation.” Philosophical Review 114, no. 4: 497–534.
Turri, John. (2011). “Believing for a Reason.” Erkenntnis 74 (3): 383–97.
Williams, Bernard. (1970). “Deciding to Believe.” In Problems of the Self. Cambridge, Cambridge University Press.
Wedgwood, Ralph. (2002). “The Aim Of Belief.” Nous 36, no. s16: 267–97.
Velleman, J. David. (2009). The Possibility of Practical Reason. Scholarly Publishing Office, University of Michigan Library.
[1] McCain, 2014.
[2] This example is modified from Flowerree (2016).
[3] I draw this conclusion from the official formulation of IB-R given on McCain, 90. There is a wrinkle to this interpretation which I will discuss in a moment.
[4] Indeed, the problem McCain raises for the doxastic view of basing seems to be a problem that will arise for any theory of doxastic justification (except perhaps coherentism). Justification is intuitively understood as chainlike. Either it will terminate in an unjustified belief, or it will result in an infinite regress.
[5] McCain, 96. “Shirley’s belief that r can be well-founded only if it is based on her evidence for r, which includes her beliefs that q and that q entails r, and those beliefs are themselves well-founded” (emphasis mine).
[6] See Turri (2011) for an explanation of the Orthodox view and an argument against it.
[7] I discuss belief formation in this section, but the same could be said of sustaining belief.
[8] Many philosophers accept that no mental state meeting this profile could count as a belief. See Bennett (1990), Hieronymi (2009), Street (2011), Shah (2003), Shah and Velleman (2005), Velleman (2009), Williams (1970), and Wedgwood (2002).
[9] This example is modified from Flowerree (2016). There, I argue against a doxastic conception of the basing relation. I have modified the example to draw out problems with IB-R. I consider implicit bias to be a cousin to wishful thinking.
[10] Numerous psychology studies have shown that this happens routinely. E.g., Steinpreis, Anders and Ritzke (1999).
[11] “There must be a possible intervention on the first variable that will result in a change in the value of the second when all other variables in the set are held fixed at some value.” McCain, 90.
[12] And it’s a good thing, otherwise we would have infinite causal chains manufacturing trivial beliefs slowing down our cognitive processing.
[13] McCain, 90.
5.15.17 |
Response
Why Explanationists Shouldn’t Make Evidential Fit Dispositional
1. Introduction
Kevin McCain’s Evidentialism and Epistemic Justification is the most thorough defense of evidentialism to date. In this work, McCain proposes insightful new theses to fill in underdeveloped parts of evidentialism. One of these new theses is an explanationist account of evidential fit that appeals to dispositional properties. We argue that this explanationist account faces counterexamples, and that, more generally, explanationists should not understand evidential fit in terms of dispositional properties.
2. Explanationist Accounts of Evidential Fit
Suppose you have the sort of visual experience one typically has when seeing a red object. Plausibly, this visual experience evidentially supports your believing that something is red. But what makes this proposition fit that evidence?
McCain provides the following theory:
Explanationist Fit (EF): p fits S’s evidence, e, at t IFF either p is part of the best explanation available to S at t for why S has e or p is available to S as a logical consequence of the best explanation available to S at t for why S has e. (65)
The first disjunct of the analysans explains why the visual experience supports believing that something is red. The proposition <something is red> is ‘part of the best explanation available to you’ for why you have that experience. The second disjunct explains why the visual experience supports believing any logical consequence of the best explanation available, such as <something is there>.
Crucial to understanding EF is ‘p is part of the best explanation available to S for why S has e’. According to McCain,
Available as part of the best explanation: S has p available as part of the best explanation for why S has e (at t) IFF: (at t) S has the concepts required to understand p and S is disposed to have a seeming that p is part of the best answer to the question “why does S have e?” on the basis of reflection alone. (67)
Note that according to this definition, ‘S has p available as part of the best explanation for why S has e’ does not entail that p is part of the best, or is even part of any, explanation for why S has e. This is because S’s being disposed to have a seeming that p is part of the best answer to some question does not entail that p really is part of the best, or is part of any, explanation of that question.1
So, a more transparent way of writing EF references dispositions rather than explanations, for the dispositions are what matter:
Explanationist Fit (EF): p fits S’s evidence, e, at t IFF S has the concepts required to understand p and, either: (i) S is disposed to have a seeming that p is part of the best answer to the question “why does S have e?” on the basis of reflection alone, or (ii) S is disposed to have a seeming that BA is the best answer to the question “why does S have e?” on the basis of reflection alone, and p is a logical consequence of BA.2
Suppose you have the concepts required to understand the proposition <something is red>. Presumably, if you were to reflect on the question “Why do I have this visual experience?”, it would seem to you that <something is red> is part of the best answer to that question. So, McCain’s theory correctly predicts that your belief that <something is red> fits your perceptual evidence.
It is easy to miss that EF is a highly subjectivist theory. In this context, roughly, a theory is subjectivist to the degree that evidential fit depends on the subject’s inclination to take p as part of the best explanation for why S has e. In the rest of this section, we will compare EF to three related explanationist theories of evidential fit, each increasing in its degree of subjectivity.
Let ‘BE’ stand for ‘the best explanation at t for why S has e.’ The least subjectivist version of explanationist fit is:
Strong Objectivist EF: p fits S’s evidence, e, at t IFF either (i) p is part of BE, or (ii) p is a logical consequence of BE.
On this view, a proposition fits your evidence simply when it’s part of (or entailed by) the best explanation for why you have the evidence. Note that Strong Objectivist EF does not require that the explanation is available to you. How inclined you are to take p to be part of the best explanation for why you have e makes no difference to evidential fit.
The following is a more subjectivist view:
Moderate Objectivist EF: p fits S’s evidence, e, at t IFF S has the concepts required to understand p and, either: (i) p is part of BE and S is disposed to have a seeming that p is part of the best answer to the question of why S has e (on the basis of reflection alone), or (ii) p is a logical consequence of BE and S is disposed to have a seeming that BE is the best answer to the question of why S has e (on the basis of reflection alone).
On this version of evidential fit, a proposition fits your evidence when it’s part of (or entailed by) the best explanation for why you have the evidence, and you’re disposed to take it to be part of this best explanation, where this just means that you’re disposed to have a seeming that it’s part of the best answer to the question of why you have that evidence. Moderate Objectivist EF is more subjectivist than Strong Objectivist EF since it requires that the explanation be available to you. On the other hand, Moderate Objectivist EF is less subjectivist than EF, which doesn’t actually require that p be part of the best explanation.
The next account is even more subjectivist and requires some set up. There is some set of explanations, {E1, …, En}, such that, for every member of {E1, …, En}, S is disposed, on the basis of reflection alone, to have a seeming that it is an answer to the question of why S has e. This is the set of explanations that are ‘available’ to S in McCain’s sense. Note that {E1, …, En} might not include all the explanations for why S has e; there might be explanations that S is not disposed to consider. Now let ‘BE*’ pick out the best of those explanations {E1, …, En}. The next account is:
Moderate Subjectivist EF: p fits S’s evidence, e, at t IFF S has the concepts required to understand p and, either: (i) p is part of BE* or (ii) p is a logical consequence of BE*.3
This view is more subjectivist than both Strong Objectivist EF and Moderate Objectivist EF since it doesn’t require that p be part of the actual best explanation for why S has e. However, it’s not as subjectivist as EF since it requires that p be part of (or a logical consequence of) the actual best of {E1, . . . , En}. EF doesn’t require that p actually be part of an explanation, of the restricted set of explanations {E1, . . . , En}, or of any other interesting set; all that’s required is that S be disposed to have a seeming that p is part of the best answer to the question of why S has e.
By canvassing these different degrees of subjectivity, we can see just how strongly subjectivist EF is. A more appropriate label for EF might be ‘Strong Subjectivist EF,’ but we will stick with ‘EF.’4
3. Problems with McCain’s Account of Evidential Fit
In 3.1, we give counterexamples that exploit the fact that, according to EF, p isn’t actually required to be a part of the best, or even an, explanation of e. In 3.2, we give a counterexample that exploits the fact that, according to subjectivist explanationist accounts, the explanation (or apparent explanation) must be dispositionally available to S. In 3.3, we show how explanationist views that appeal to dispositional accounts of available explanations face a new evil demon problem.
3.1 Weird Dispositions Counterexamples
Paranoid: Unbeknownst to Bucky, a demon has tampered with him and has given him a certain complex disposition. Now, when he has the visual experience of his friend Steve smiling, he is disposed to have a seeming that <Steve wants to kill me> is part of the best answer to the question of why he has this visual experience. Bucky has no memory or past experience of Steve ever posing a threat. They are—or were—friendly acquaintances.
According to EF, <Steve wants to kill me> fits Bucky’s visual experience of Steve smiling. But intuitively, this is false. This visual experience might evidentially fit <Steve is smiling> or <Steve is happy>, but it does not fit <Steve wants to kill me>.
Consider another version of Paranoid, call it ‘Nonsensical’, in which the demon had instead caused Bucky to have the disposition to have a seeming that <grass is green> is part of the best answer to the question of why he has the visual experience of Steve smiling. EF has the counterintuitive result that <grass is green> fits Bucky’s evidence. These cases show that EF is too permissive. It allows anything that you’re disposed to take as part of the best explanation for why you have your evidence to count, even if it’s not a good explanation (as in Paranoid) or an explanation at all (as in Nonsensical).
3.2 Impoverished Dispositions Counterexample
McCain might be tempted to give up EF and retreat to Moderate Subjectivist EF or Moderate Objectivist EF, which require that p is part of an, or the best, explanation. However, the following case poses a problem even for these less subjectivist views.
Blue Sky: Suppose Carla lies resting in a field, closing her eyes and occasionally looking up at the sky. Nothing interesting is going on with the sky: it’s clear and blue whenever Carla happens to open her eyes. At t, Carla opens her eyes and has the mental state of being appeared to blue-skyly. At t Carla is disposed to have the seeming that <I opened my eyes> is the best answer to the question of why she is appeared to blue-skyly. At t, Carla is not disposed to have any other seemings about other answers, or parts of answers, to the question of why she is appeared to blue-skyly.
According to EF, <Carla opened her eyes> fits her evidence, that is, her mental state of being appeared to blue-skyly. This seems correct. But it also seems that propositions like <Carla looked at the sky> or <the sky is blue> fit her evidence. And according to EF they do not: they are not part of (or entailed by) the best explanation available to Carla.
This is also a problem for both Moderate Objectivist EF and Moderate Subjectivist EF. Plausibly, <Carla opened her eyes> is part of the best explanation for why Carla has her visual experience. So, since this explanation is available to Carla, <Carla opened her eyes> fits her evidence according to Moderate Objectivist EF and Moderate Subjectivist EF. However, since this is the only explanation (or only part of an explanation) available to Carla, no other proposition fits Carla’s evidence according to Moderate Subjectivist EF or Moderate Objectivist EF.5
Interestingly, Strong Objectivist EF seems to get the right result in all these cases. Plausibly, neither <Steve wants to kill me> nor <grass is green> are part of the best explanation for why Bucky has his evidence, so they do not fit his evidence according to Strong Objectivist EF. But <Steve is smiling> and <Steve is happy> are part of the best explanation for why Bucky has his evidence, so they fit it according to Strong Objectivist EF. Also, it’s plausible that <Carla opened her eyes>, <Carla looked at the sky>, and <the sky is blue> are all part of the best explanation for why Carla has her evidence, so they all fit her evidence according to Strong Objectivist EF.
3.3 The New Evil Demon Problem
The New Evil Demon Problem (NEDP) purports to show that certain properties are irrelevant to whether a belief is justified. For example, consider the view that a belief’s being reliably formed is relevant to whether it is justified. Now suppose that Smith’s belief seems justified and is formed by a reliable process. We can imagine a mental duplicate of Smith, Smith*, whose belief is not formed by a reliable process due to the machinations of a demon. Intuitively, Smith and Smith* are equally justified in their belief. It seems that any two individuals who are identical except for the mere difference of reliable belief production will be justificationally identical. This seems to show that reliable belief formation is not relevant to justification.6
We argue that a version of the NEDP shows that the dispositions McCain appeals to are irrelevant to justification. Consider Paranoid. Imagine a Bucky* who has the same memories, beliefs, and experiences as Bucky but who never had a demon tamper with him. He thereby does not have the paranoid disposition. When Bucky and Bucky* have qualitatively identical visual experiences at t of Steve smiling, it follows from EF that Bucky has evidence that fits <Steve wants to kill me> while Bucky* does not.7 Given evidentialism and EF, Bucky has more justification for believing <Steve wants to kill me> at t than Bucky* does. But this is counterintuitive. It seems that the two Buckys are justificationally alike.
Now consider the dispositional requirements of Moderate Subjective EF and Moderate Objective EF. Suppose Bucky** is just like Bucky*, but a demon has erased his normal human disposition to have a seeming that <Steve is smiling> is part of the best explanation for why he has the visual experience of Steve smiling. On either of the two theories, it’s plausible that Bucky* has evidence that fits <Steve is smiling>. However, Bucky** does not because he lacks the relevant disposition. This is counterintuitive. It seems that they are justificationally alike.
These instances of the NEDP show that the dispositions McCain appeals to are irrelevant to justification, just as more standard versions of the NEDP show that reliable belief production is irrelevant. It seems that any two individuals who are identical except for the mere difference of dispositional availability of explanations will be justificationally identical. Strong Objectivist EF is not subject to this version of the NEDP since it does not appeal to dispositions.
We have argued that there are counterexamples to EF. One might think that EF merely requires tweaking. But Moderate Subjectivist EF and Moderate Objectivist EF also face counterexamples. Furthermore, our discussion of the NEDP reveals that the underlying problem is the appeal to dispositions. Strong Objectivist EF, which does not appeal to them, faces neither the counterexamples nor the NEDP. We conclude that explanationists should not analyze evidential fit in terms of the dispositional availability of explanations.8
Works Cited
McCain, Kevin. Evidentialism and Epistemic Justification. New York: Routledge, 2014.
Moon, Andrew. “Three Forms of Internalism and the New Evil Demon Problem.” Episteme 9 (2012) 345–60.
Poston, Ted. Reason and Explanation: A Defense of Explanatory Coherentism. New York: Palgrave Macmillan, 2014.
Assuming that answers to questions are propositions, our thought is that not every proposition can be an explanation for anything. For example, <Jupiter is the largest planet in the solar system> is not a poor explanation for the fact that 2 + 2 = 4; it’s not an explanation at all.↩
It’s possible that the account is actually:
p fits S’s evidence, e, at t IFF S has the concepts required to understand p and, either: S is disposed to have a seeming that p is part of the best answer to the question “why does S have e?” on the basis of reflection alone, or S is disposed to have a seeming that p is a logical consequence of the best answer to the question “why does S have e?” on the basis of reflection alone.
The choice between the two versions depends on how McCain understands ‘p is available to S as a logical consequence of the best explanation available to S.’ We think this version is less charitable and will assume the more objectivist understanding in what follows, but our argument does not depend on this choice.↩
Thanks to Liz Jackson, Dustin Crummett, and especially Philip Swenson for help formulating Moderate Subjectivist EF.↩
Note that a theory of evidential fit need not fall under McCain’s general framework in order to be explanationist. For example, on Ted Poston’s (2014, 87–95) explanationist view ‘Ex-J’, “S has justification for believing p if and only if p is a member of a sufficiently virtuous explanatory system, E, and E is more virtuous than any competing system E” (87). According to Poston, evidence “resides in the virtues of the entirety of a system of beliefs” (93) and “[a] proposition is a member of an explanatory system by being a part of an explanans or part of an explanandum” (87). Now, it is not obvious how Ex-J can be converted into a theory of evidential fit, but note that nothing in his theory implies that p must explain why S has her evidence, or that S must be disposed to have a seeming that p is the best answer to why she has her evidence. So, Poston’s theory of evidential fit, when developed, may be very different from McCain’s.↩
One option for the subjectivist about explanationist evidential fit would be to describe the evidence being explained in such a way that one would be more likely to be disposed have the ‘right kind’ of seeming about what best explains it. For example, a description of Carla’s evidence with an appropriate contrast—like the mental state of being appeared to blue-skyly rather than green-grassly—could not be best explained by the proposition that Carla opened her eyes. This fix would not save EF from weird disposition cases, but it would make versions like Moderate Subjectivist EF and Moderate Objectivist EF more plausible.↩
For a definition and further explanation of the NEDP, see Moon, 348.↩
To ensure that Bucky and Bucky* are identical with respect to memories, beliefs, and experiences at t, suppose that Bucky’s disposition is never manifest because he never reflects: even though he has the paranoid disposition at t, it doesn’t seem to him at t that Steve wants to kill him or that <Steve wants to kill me> is the best answer to the question of why he has his visual experience.↩
Thanks to Kevin McCain, Ted Poston, and Philip Swenson for helpful discussion.↩
5.22.17 |
Response
Coherence Concerns for McCain’s Explanationist Evidentialism
Introduction
Kevin McCain’s Evidentialism and Epistemic Justification contains careful, well-organized argumentation in the service of an important and clearly defined positive project: to rectify the fact that “Evidentialism remains more of a schema for a theory of epistemic justification than a full-fledged theory” (4). McCain calls the full-fledged theory that he develops Explanationist Evidentialism (EE), the core idea of which is that S justifiedly believes that p when p is part of the best explanation for S’s non-factive mental states.1
While I find much to agree with in McCain’s book, I think that EE ultimately fails to capture the importance of coherence to epistemic justification.2 Below, I present a (schematic) case that I argue is a counterexample to EE when combined with some plausible epistemological principles.
Two Features of EE
The most relevant feature of EE to this discussion is McCain’s moderate view of evidence possession, MVP*.
MVP*
S has p available as evidence relevant to q at t iff at t S is currently aware of p or S is disposed to bring p to mind when reflecting on the question of q’s truth.” (51)
There is a second principle that I will take to be a feature of EE despite its not having been explicitly endorsed by McCain. However, I take it to be an implicit part of McCain’s overall view, given that he takes it to be “very important” that his theory of well-foundedness includes a no-defeater condition (119).3 McCain does not discuss the nature of defeat, but he does at least seem to have it that if q functions as a defeater for S’s belief that p, then q is part of S’s total evidence for p.4 Since it would be ad hoc to include S’s beliefs about q or ~q in S’s evidence for p only in cases in which q actually defeats S’s justification for p, I will below treat the following corollary as part of the EE package.[/footnote]I follow McCain in talking of “evidence for p,” which he does in an attempt to remain neutral on the question of whether one’s evidence consists in one’s non-factive, assertive mental attitudes or their propositional objects.[/footnote]
Defeater Corollary
If S’s justification for p would be defeated were S to believe that q, then S has available as evidence relevant to p S’s doxastic attitudes with respect to q and ~q of which S is aware or is disposed to bring to mind when reflecting on the question of p’s truth.5
The Coherence Concern
Consider the following, schematic case.
Incoherence Case
- S believes that p, which is part of the best explanation for S’s total evidence (as defined by MVP*).
- S believes that q, r, and s.
- ~q would defeat S’s justification for p.
- S is not disposed to bring either r or s to mind when reflecting on the question of p’s truth.
- The propositions q, r, and s are mutually inconsistent.
(B) and (C) tell us, in combination with the defeater corollary and MVP* respectively, that q, but neither r nor s, are part of S’s evidence for p. But (D) tells us that S’s belief that q is a member of an incoherent belief-set. This, I argue, is a spanner in the works given the following plausible principles.
Justified Basis
S’s belief that p is justified only if the beliefs on which it is based are themselves justified.
Unjustified Incoherence
S’s belief that p is unjustified if p is a member of a set of S’s beliefs that is incoherent.6
Respecting this pair of principles in the Incoherence Case yields the verdict that S’s belief that p is unjustified. This is because S’s justification for p is (partly) based on q, which is unjustified for S because it fails to cohere with r and s. But (A) tells us that S’s belief that p is justified on EE—r and s are not part of S’s evidence for p, so they do not come into play on the view, and, while ~q would act as a defeater, S in fact believes that q. So, EE yields a false positive for any set of beliefs that fits the Incoherence Case schema, if Unjustified Incoherence and Justified Basis are true.
Are they true? Justified Basis is the intuitive first step in the traditional regress problem (solutions to which distinguish foundationalism, coherentism, and infinitism7. Although he considers the question of where in the traditional taxonomy EE belongs, McCain does not discuss the traditional regress motivation for the distinctions, and its like is held by almost all internalists.8 That leaves Unjustified Incoherence as the most likely target for a counter-attack.
Indeed, as it stands, few will endorse the principle. If nothing else, it is implausible because (as Frank Ramsey noted long ago) we none of us have a globally coherent set of beliefs (Ramsey, 1990).9 Therefore, taken strictly, Unjustified Incoherence leads directly to skepticism—a consequence McCain would likely see as beyond the pale (despite admirably rejecting turning anti-skepticism into an assumption). However, it is also clear that incoherence undermines justification in at least some cases, so it seems that what we need to restrict, rather than abandon, the principle. Unfortunately, this is no simple matter. There is a tension between the restriction’s tightness and its plausibility that is not unlike the tension that leads McCain to adopt a moderate view of evidence possession over inclusive and restrictive variants.
Considering MVP* puts a fine point on the problem. Salvaging EE via a restriction on Unjustified Incoherence requires finding a restriction such that q is unjustified for S, in virtue of its being inconsistent with S’s beliefs that r and s, only when r and s are part of S’s evidence for p according to MVP*.10 But, given the quirks of human psychology, I am skeptical, to say the least, of finding any non–ad hoc restriction of this sort.
Options
There are certainly other options. McCain could restrict MVP* instead. Though, here again, I see no non–ad hoc helpful way to do so (at least short of abandoning it for its accessibilist counterpart, RVP11). Similar dangers lie the way of amending the Defeater Corollary.
Finally, there is the possibility of rejecting Justified Basis. This might even be McCain’s initial inclination, given that his statement of EE places no justification condition on evidence. But without going full accessibilist, it seems a bridge too far that, for example, p could be justified for me despite my evidence for it consisting entirely in the products of wishful thinking or laughably sloppy reasoning.
At this point, I will leave it to McCain to attempt to make one of these unsavory options more palatable, or perhaps to concoct a dish of his own.
References
Littlejohn, Clayton. “Stop Making Sense? On a Puzzle about Rationality.” Philosophy and Phenomenological Research, 2015.
McCain, Kevin. Evidentialism and Epistemic Justification. New York: Routledge, 2014.
Ramsey, Frank. “Truth and Probability.” In Philosophical Papers, edited by D. H. Mellor, 52–109. Cambridge: Cambridge University Press, 1990.
Worsnip, Alex. “The Conflict of Evidence and Coherence.” Philosophy and Phenomenological Research, 2015.
This is a brutally rough statement of the nature of propositional justification on EE. For the full statement, and that of well-foundedness (what is often called “doxastic justification”), see 117–18.↩
Recently, Clayton Littlejohn (2015)—as well as Alex Worsnip (2015) and others—has criticized evidentialism by appealing specifically to considerations coherence between first and higher order attitudes. While I think that EE has problems along these lines as well, I do not have anything to add to Littlejohn’s argument. I will therefore focus on a problem having to do with first order coherence.↩
Ex-WF (IV), the details of which are not important for our current purpose, but are found on p. 118.↩
E.g., “It is assumed that in the examples S’s total evidence does not include defeaters relevant to the proposition being discussed” (65).↩
I have elided temporal references, but the principle should be read as synchronic.↩
Many epistemologists would want to include a rider to the effect that S would become aware of the incoherence upon reflection on the belief-set. We can stipulate that S’s beliefs that q, r, and s meet any such condition, so I leave it elided.↩
And the newcomer—foundherentism—in which camp McCain seems to think EE is best seen as falling (121)↩
At least, it is if we restrict it to non-basic beliefs—but of course p is a non-basic belief in the incoherence case.↩
There are also looming concerns about preface and lottery paradoxes, as Andrew Moon has pointed out to me.↩
This would lead, presumably, to a rejection of (A) on the basis that there is no best explanation for an incoherent set of mental states.↩
McCain’s label for Richard Feldman’s restrictive view of evidence possession, against which McCain argues against at length (35–49)↩
5.1.17 | Brian Cutter and Philip Swenson
Response
Does It Matter Which Explanation Is Best?
Explanationists hold that epistemic justification depends fundamentally on explanatory considerations.1 Kevin McCain’s excellent book Evidentialism and Epistemic Justification defends an evidentialist version of Explanationism. We greatly benefited from reading McCain’s book and are sympathetic with much of what he has to say. But we will suggest one modification to his account. McCain requires that the best available explanation provide support for a proposition in order for the proposition to be justified. We will argue that this requirement faces difficulties and suggest an alternative approach. Explanationists should accept that epistemic justification does not just depend on the support it receives from the best explanation of one’s evidence, but on the collective support it receives from all competing explanations of one’s evidence.
McCain appears to be committed to both of the following:
Explanationism (roughly construed): Whether p is justified for S depends fundamentally on explanatory considerations.2
And also:
Best Explanationism: Whether p is justified for S depends fundamentally on p’s relationship to the best (or best available) explanation of S’s total evidence.
In his book, McCain holds that S is justified in believing p if and only if either
(i) p is part of the best explanation of S’s evidence available to S
or
(ii) p is available to S as a logical consequence of that explanation.3
In a more recent paper, he replaces requirement (ii) with the following:
(iii) p is available to S as an explanatory consequence of the best explanation [of S’s evidence] available to S.4
Both of these views are versions of Best Explanationism. They both say that justification depends on some relationship holding between p and the best available explanation. It is not surprising that McCain accepts Best Explanationism. It is common for Explanationists to think that justification should be accounted for in terms of which explanation is best.5 We will argue that Best Explanationism creates unnecessary difficulties for Explanationists and that there is a more plausible form of Explanationism available, one which does not assign the best explanation a position of overriding privilege.
1: Worries for Best Explanationism
Consider the following situation. There are three (mutually exclusive, jointly exhaustive) potential explanations of your total evidence available, and they have the following epistemic probabilities for you:
E1: 34% probability
E2: 33% probability
E3: 33% probability
E1 contains p as a part, while E2 and E3 both contain ~p.
There are two potential worries that arise for McCain (and Best Explanationism in general) as a result of this scenario.
Worry 1: Can McCain (and Best Explanationism in general) account for the fact that you should not believe p?
Worry 2: Can McCain (and Best Explanationism in general) account for the fact that you are justified in believing ~p? (If you do not think that a 66% epistemic probability is sufficient for justified belief, then imagine a version of the case where there are 100 available explanations and all but one, which is very slightly more likely than the rest, contain ~p.)
McCain has two plausible responses to Worry 1. First, McCain could require that in order for you to be justified in believing p, E1 must not only be the best explanation, “it must also be a sufficiently good explanation” (McCain 2015, 339). Perhaps E1 does not qualify as “sufficiently good,” since it is only 34% likely on your evidence. Second, McCain has suggested in correspondence that there may be a more general explanation available which is better than E1. Perhaps:
E4: Some explanation other than E1 is true.
is a better explanation of your evidence than E1.
Both of these approaches seem like initially promising responses to Worry 1. Worry 2, however, is more serious. In order to secure the result that you are justified in believing ~p, McCain must establish that ~p is either part of the best available explanation or entailed by the best available explanation (or alternatively, is an “explanatory consequence” of the best available explanation). McCain could attempt to appeal to explanations along the following lines:
E5: Either E2 or E3 is true.
Or, more generally:
E6: Some explanation that includes ~p is true.
E5 and E6 both entail the truth of ~p. And one could make a case that they are better explanations than E1. However, it is not plausible that either of them are the best explanation of your evidence. Consider:
E7: Either E1 or E2 is true.
Once we allow general or disjunctive explanations into play, E7 looks pretty good. Given your evidence, E7 is 67% probable, while explanations like E5 and E6 are only 66% probable. Thus E7 looks like a better explanation than either E5 or E6.
E7 does not entail ~p. In fact, given E7, ~p is more likely to be false then true. (This is because E1 contains p and has a higher probability than E2.) Thus it is implausible that E7 either contains ~p in the relevant sense or has ~p as an explanatory consequence.
So it looks like Worry 2 creates significant trouble for Best Explanationism. In order to respond to it, the Best Explanationist would have to find an explanation that is better than E1 and E7, and is related to ~p in the appropriate way. This looks like a difficult task.
2: An Alternative Approach
Reflection on the foregoing leads us to think that, even by Explanationist lights, Best Explanationism is misguided. Intuitively, you can be justified in believing ~p if the available explanations of your evidence collectively support ~p to a sufficiently high degree, even if the best explanation does not. E2 and E3 both provide some support for ~p. The combined strength of these different sources of support suffice to justify you in believing ~p. Instead of Best Explanationism, Explanationists should therefore accept:
Multiple Source Explanationism: S’s justification for believing p depends on the collective support that p receives from all competing explanations of S’s evidence.
We conclude by proposing a (somewhat idealized) formal framework for Multiple Source Explanationism to illustrate how our justification for believing a proposition is sensitive to its relationship to all the candidate explanations for our evidence.
Let E1, . . . , En be the complete menu of competing explanations for our total evidence. For simplicity, we’ll assume that E1, . . . , En form a partition on logical space, i.e., that they are pairwise inconsistent and their disjunction is logically necessary. From here, we make two theoretical assumptions. First, we take for granted that explanations can be better or worse and, more specifically, that there is gradable aspect or dimension of explanatory goodness that corresponds to (perhaps determines) the degree of confidence we rationally ought to have in the truth of the explanation, given our total evidence.6 We make the common idealizing assumption that levels of confidence (“credences”) can be represented by real numbers in the interval [0, 1]. And since the relevant dimension of explanatory goodness for an explanation E (symbolized as “G(E)”) corresponds to the rational credence in E given our total evidence (symbolized as “C(E)”) we’ll assume that G can be measured on a similar scale. That gives us:
Assumption 1: C(E) = G(E)
It would be convenient if we could assume that every candidate explanation either entails p or entails ~p (as with E1–E3 above). For in that case, the question “how much justification do we have to believe p?”—or, better, “how confident should we be in the truth of p?”—would have a straightforward answer: our confidence in p should be equal to the sum of the G-values over each Ei that entails p. But there is no reason to expect this convenient assumption to hold in general. In addition to explanations that entail p and explanations that entail ~p, there will typically be a range of intermediate cases, in which an explanation makes p probable to some positive degree short of certainty. (McCain [2015] appears to grant something along these lines with his appeal to non-entailed “explanatory consequences.”) Thus, our second assumption: an explanation can (as we’ll say, for lack of a better word) support a proposition p to a greater or lesser extent. More specifically, we’ll assume that the degree to which p is supported by an explanation E (symbolized as “S(p, E)”) corresponds to (perhaps determines) the level of confidence one rationally ought to have in p given E. That gives us:
Assumption 2: C(p|E) = S(p, E)
We now ask: are we justified in believing p? Or, better: how confident should we be in the truth of p? Answer: our confidence in p should be equal to the weighted sum of the support given to p by all the candidate explanations of our total evidence, with weights provided by the G-value of each explanation. That is:
Total Support: C(p) = S(p, E1)G(E1) + . . . + S(p, En)G(En)
The reader may notice that Total Support takes the form of the theorem of total probability, according to which
Total Probability: Pr(B) = Pr(B|A1)Pr(A1) + . . . + Pr(B|An)Pr(An),
where B is any proposition, and A1, . . . , An form a partition on logical space. This is no coincidence. Given the assumption that rational credences conform to the axioms of the probability calculus, Total Support is a straightforward consequence of the theorem of total probability, given Assumptions 1 and 2.
From the perspective of Multiple Source Explanationism, we can see that there cannot be a general recipe for determining our degree of justification for p that relies exclusively on information about p’s relationship to the best explanation. Formally, this is because there is no way of working out the value of C(p) in the Total Support equation if we’re only given information about the values of S(p, Ei) and G(Ei) for a single explanation Ei (except in the special case where G(Ei) = 1). As a simple illustration of this point, let’s consider two cases. In each, there are only two explanations for our total evidence, “Best Explanation” and “Worst Explanation” (as before, we assume they partition logical space), with epistemic probabilities and support relations as indicated below:
Case 1:
Best Explanation: 60% likely; supports p to degree .4
Worst explanation: 40% likely; supports p to degree 0 (entails ~p)
Case 2:
Best Explanation: 60% likely; supports p to degree .4
Worst Explanation: 40% likely; supports p to degree 1 (entails p)
In Case 1, our credence in p should be .24. In Case 2, our credence in p should be .64. But notice that the facts about p’s relationship to Best Explanation (including facts about the goodness of Best Explanation) are the same in each case. Any theory that only takes account of the best explanation will therefore lack the resources to generate the intuitively correct result that we ought to have different attitudes toward p in these cases. The general lesson is that the attitude we are rationally justified in taking toward a proposition is not a function of its relationship to the best explanation alone. Given the Explanationist assumption that epistemic justification is fully determined by explanatory considerations, we must allow that epistemic justification is a function of a proposition’s relationship to all the available explanations of our evidence.
References
McCain, Kevin. “Explanationism: Defended on All Sides.” Logos & Episteme 6:3 (2015) 333–49.
McCain, Kevin. Evidentialism and Epistemic Justification. New York: Routledge, 2014.
Poston, Ted. Reason and Explanation: A Defense of Explanatory Coherentism. Palgrave Macmillan, 2014.
Thanks to Simon Goldstein, Kevin McCain and Andrew Moon for helpful comments.↩
Ted Poston offers a somewhat different definition. “Explanationism is the view that one’s normative standing in the space of reasons is constituted by one’s explanatory position” (2014, p. 69).↩
Note that this is our statement of McCain’s view. See McCain (2014, p. 117) for the official statement.↩
By “p is an explanatory consequence of the best explanation available to S” McCain means that “if p were true, the best available explanation of S’s evidence would better explain its truth than it would the truth of ~p, if ~p were true” (2015, 339).↩
Poston (2014) also endorses something along the lines of Best Explanationism.↩
We emphasize that this is only an aspect or dimension of explanatory goodness because the overall extent to which E is a good explanation for some phenomenon X is not only a matter of how likely E is given X, but also (inter alia) how likely X is given E. This is why Jones received something nice in the mail may in some contexts be a better explanation of the fact that Jones is happy than Jones received something in the mail, though the latter is more likely given the explanandum.↩
5.1.17 | Kevin McCain
Reply
It Matters Which Explanation Is Best: A Reply to Cutter and Swenson
Brian Cutter and Philip Swenson (hereafter “C&S”) challenge Explanationist Evidentialism on the grounds that it makes justification depend upon the best available explanation. The worry that C&S raise, if successful, threatens not just Explanationist Evidentialism, but any theory of epistemic justification that restricts justification to the best explanation (I will follow C&S in referring to such views as “Best Explanationism”). Although this sort of objection to explanationism is one that is often brought up in conversations, it is seldom made explicit in print.1 I am grateful to C&S for clearly presenting the challenge and explaining its purported force, though I will be arguing that it ultimately fails as an objection to Explanationist Evidentialism, and Best Explanationism in general.
Before diving into the details of C&S’s case against Best Explanationism it is worth pausing to note that in addition to raising an objection they also offer an alternative way of developing explanationism. C&S suggest that “Multiple Source Explanationism” can avoid the problem that they maintain arises for Best Explanationism. According to Multiple Source Explanationism, justification isn’t a matter of which explanation is the best. On the contrary, C&S’s theory construes justification as “a function of a proposition’s relationship to all the available explanations of our evidence.” C&S’s proposal is interesting and worthy of careful consideration. I should mention at the outset that it strikes me as a theory with some initial plausibility. Additionally, it is should be noted that one could accept C&S’s Multiple Source Explanationism without abandoning the central explanationist tenant that justification ultimately depends on one’s overall explanatory position. So, although this view is a rival of my own, it’s still in the explanationist family. Of course, whether one should accept Multiple Source Explanationism or a form of Best Explanationism, such as my Explanationist Evidentialism, comes down to how they stack up as theories of epistemic justification. In other words, the decision between these theories comes down to which one provides us with the best explanations of the relevant data. Unfortunately, I do not have the space to thoroughly evaluate the comparative merits of these competing explanationist approaches here. Instead, I will focus on showing that C&S’s attack on Best Explanationism doesn’t motivate accepting their theory because it fails to pose a genuine problem for Best Explanationism.
In order to illustrate their purported problem for Best Explanationism C&S ask us to consider a situation where “there are three (mutually exclusive, jointly exhaustive) potential explanations of your total evidence available” to you: E1, E2, and E3. The epistemic probabilities for you for these explanations is as follows: E1 = .34, E2 = .33, and E3 = .33. C&S add that “E1 contains p as a part, while E2 and E3 both contain ~p.” What’s thought to make this case problematic for Best Explanationism is that it seems that p is part of the best explanation of your evidence (E1 is more epistemically probable than either of the other alternatives), but as C&S point out the probability of p in this case is only .34, but the probability of ~p is .66. Hence, it seems that you should believe that ~p is true even though p is part of the best explanation of your evidence.2 C&S claim that this fact is contrary to the verdict that Best Explanationism yields in this case.3 So, it may appear that Best Explanationism is in serious trouble.
Initial appearances notwithstanding, Best Explanationism is not impugned by the sort of case that C&S describe. As a matter of fact, Best Explanationism yields the intuitively correct result that you should believe ~p in this case. Recall, Best Explanationism says (roughly) that you should believe that a particular proposition is true when it is part of the best explanation of your total evidence. In this case the best explanation of your evidence includes that the probability of p = .34 and the probability of ~p = .66. The reason for this is that your total evidence includes the epistemic probabilities that C&S mention for E1, E2, and E3. Consequently, the best explanation of your total evidence is that ~p has probability .66. Assuming that probabilities link up with belief in the way that C&S assume (high enough probability means that one should believe the proposition in question), your total evidence justifies you in believing ~p.
It is worth unpacking this response on behalf of Best Explanationism a bit more. This response rests on the fact that the explanation of which p is a part, E1, is not the best explanation of all your evidence. Your evidence includes that it is almost twice as likely that E1 is false than it is that E1 is true. As a result, even though E1 is the best explanation of a portion of your evidence, the best explanation of your total evidence includes what C&S call “E4,” “Some explanation other than E1 is true.” Of course, as C&S point out the truth of E4 by itself isn’t enough for Best Explanationism to deliver the result that you should believe that ~p. Fortunately for Best Explanationism, the best explanation of your total evidence also includes the proposition <If some explanation other than E1 is true, then ~p is true>. Why is this? It is because as C&S have set things up your evidence includes the information that the only alternatives to E1 include ~p (after all, they stipulate that E1, E2, and E3 are “jointly exhaustive”). Now, plausible forms of Best Explanationism, such as my Explanationist Evidentialism, allow that a proposition is justified for you when it is either part of the best explanation of your total evidence or a logical consequence of the best explanation of your total evidence.4 It is clear that <Some explanation other than E1 is true> and <If some explanation other then E1 is true, then ~p is true> together entail that ~p is true. Thus, given that these two propositions are part of the best explanation of your total evidence, Best Explanationism yields that believing ~p is justified for you. And, as we’ve seen there’s good reason to think that these propositions are part of the best explanation of your total evidence. Therefore, Best Explanationism provides the intuitively correct result in C&S’s case. As a result, while C&S do a very nice job articulating an objection that often arises when one is discussing explanationism, they don’t provide a reason to abandon Best Explanationism.5
A notable exception is Richard Fumerton, Metaepistemology and Skepticism (Lanham, MD: Rowman & Littlefield, 1995).↩
C&S note that if one doesn’t think that .66 probability is sufficient for justifying belief, their case can be modified so that the probability of ~p is very high even though the explanation containing p is still better than any of the individual ~p explanations. In light of this, I’m willing to grant C&S’s assumption that .66 probability is sufficiently high to justify belief.↩
C&S’s challenge is a version of what Ted Poston and I (unpublished manuscript) have termed the “Disjunction Objection” to Best Explanationism.↩
As C&S note, I actually think that the best way to construe Explanationist Evidentialism is in terms of explanatory consequence rather than logical consequence. However, for the present purpose this distinction will not make a difference because both ways of understanding Explanationist Evidentialism produce the same result in this case. Readers interested in seeing why I opt for explanatory consequence are encouraged to see Kevin McCain, “Explanationism: Defended on All Sides,” Logos & Episteme 6 (2015) 333–49.↩
Thanks to Matt Frise for helpful discussion.↩