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
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
- Each ei ∈ 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 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*
- 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.