Monday, October 16, 2006

Experience and Testimony

People commonly talk about "private" evidence, had on the basis of personal experiences that aren't accessible to other people. But I'm not convinced that there is any such thing. Suppose that a subject S has an experience E, and thereupon concludes that C. ('E' might be a religious experience, for instance, and 'C' the proposition that God exists.) If S then tells me about her experience in sufficient detail, and I trust that she is sincere, then surely I have just as much evidence as S does for C. We both recognize the objective fact: (O) "S had an experience E". So where's the asymmetry? We may state this as a dilemma: either O is good evidence for C, or it is not. If it is, then I (and S) should believe C. If it isn't, then S (and I) should not believe C. Either way, there's no epistemic difference between S and I. There's no "private" evidence that she cannot share through testimony.

Few of us would think it epistemically justified to believe in aliens or deities on the basis of your neighbour's "experience" of being abducted by aliens or visited by God. But your neighbour has no further, private evidence, and hence is in the same epistemic position as you. That is, they shouldn't believe in these things on their basis of their experiences either. What everyone alike should conclude is that the neighbour was hallucinating, dreaming, or some such.

I assume here that justification is a relation between propositions. When we say that a conclusion is justified by experience, this is really shorthand for saying that it's justified by the proposition that one had such an experience. There's nothing essentially "private" about such propositions, of course; knowledge of them can be transmitted through testimony just as for any other proposition. I can come to know that S had experience E, simply by S telling me so!

The defender of private evidence will need to claim that justification can be non-propositional. They will want to say that it is the first-personal event of having experience E, rather than the objective fact that this event occurred, which justifies one's belief in C. But that sounds bizarre to me. What is it about the subjective "having" of experiences that's so special, or that's of evidential import?


  1. My guess is that the experience in question is generally supposed to contain some sort of basic qualitative compulsion. Why that would count as evidence I have no idea, but in my experience that often seems to be the suggestion. (I am also, I have to admit, suspicious that such a qualitative compulsion actually shows up - it is a very convenient excuse.)

    Couldn't we just say, though, that whatever 'evidence' is it's something that we'd have to be able to give someone else as a reason counting in favor of whatever it is evidence for? This would seem to discount any sort of truly private evidence quite neatly, of course, but I'm not sure how one could make sense of 'evidence' in a way which wasn't at least somewhat public.

  2. One assumption in the original post is that the experience is communicable: “If she could describe it in enough detail…” A mystic might defend herself with the claim that her experience was intensely rich and otherworldly, which made it impossible to convey in words. (One reason for this might be because the experience involved a “basic qualitative compulsion.” But perhaps there are other, less dubious reasons for incommunicability). This seems like a natural defence to make: certainly it is an understandable feature of RE’s that they are hard to convey in words, and I notice that phrases like “it is hard to describe, but..” are present in the linked post. This defence might also sound more plausible when it is used for long-term kinds of religious experience, rather than the “sudden revelations” that most immediately spring to mind when one thinks about “religious experiences.” I have a vague theory that for most religious people belief comes about not through sudden bursts of insight, but through a slow accumulation of feelings, thoughts and experiences, each one of which is un-compelling on its own, even mundane on its own, but which all come together to give some sort of coherent picture of things. If that is the case, then one would not expect a person to be able to communicate all of the “evidence” that gives rise to their belief. (Perhaps religious belief is similar, in this way, to beliefs about the general moral character of individuals: I believe quite strongly that my flatmate is a truly “good” person, but I would find it very difficult to put into words all of the thoughts and feelings that give rise to that belief.)

  3. If we're going with a reliabilist account, then whether the experience constitutes knowledge depends on whether the experience comes from something real via a reliable source. If that is the case, it counts as knowledge. But then it seems also to be true that the transferral of information via testimony can be reliable at truth-transference, which means the reporting through testimony of the experience can, when it leads to a true belief in the hearer, lead to knowledge.

    So you're right that the asymmetry may not be there, but it doesn't necessarily undermine these private experiences as not knowledge, because it could just as easily mean that other people can have knowledge via testimony about such experiences.

  4. Interesting post- I attacked a similar subject on my blog here but with a different angle. The problem to me is that even if you were wrong- such decisions can't be the basis of political judgements because politicians have to appeal on the basis of what we all know. Thanks for this though- it fleshes out the other side of the thought which I didn't do and is much better argued and more rigorous than my posting- so thanks.

  5. Coming here from one of your more recent posts where you linked to this.

    I think the big problem is that even if justification is propositional the number of propositions I have as the first person judge of my perceptions is radically larger than what the third person judge of my testimony has.

    If I see a UFO the number of propositions entailed by that perception is huge. Much larger than included in any testimony. Further I have access to propositions about my mental states over time. (i.e. providing justifications for whether my perception was reliable)

    Clearly, for instance, my perception of a UFO would be different in terms of justification if I'd been using drugs, or blacking out or so forth. The person hearing my testimony has no access to that information.


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