Belief and Stability

Robbie Williams has just posted an excellent paper on Accuracy, Logic and Degree of Belief. I wanted to highlight one of parts with which I strongly agreed.

The overarching idea is that in adopting doxastic attitudes to a proposition, we incur commitment to persist in those attitudes if no new evidence is forthcoming (where persistence is understood as not changing one’s mind—-i.e. not adopting a different attitude to the same proposition. I discuss cases of simply ignoring the proposition below). In the limiting case, consider a situation where one simply moves from one moment to the next, with no new input or reflection. It would be bizarre to change ones (non-indexical) beliefs in such circumstances. Insofar as action, over time, is based on one’s beliefs, it would mean that a course of action started at one time might be abandoned (since it no longer maximizes expected utility) without any prompting from reflection or experience.

Persistence might be construed as a (widescope) diachronic norm on belief. Alternatively, a disposition to retain an attitude to the proposition over time might be constitutive of belief. If what makes something count as a belief is its functional role, then the reflections on extended action above motivate this kind of claim.

I think persistence is, at least for belief, both constitutive and normative. If a kind of state is not disposed to persist, that state is not belief. And if a token of that belief does not persist, in the absence of good reasons for it to be reconsidered, that’s a normative failing.

I ended up with a view like this via Richard Holton’s work. But I hadn’t realised it had an even more notable pedigree. At the Formal Epistemology Workshop, Hannes Leitgeb highlighted the work my colleague Louis Loeb has done in drawing attention to the importance of persistence to Hume’s theory of belief. (For a brief view of this, here is a review of Louis’s 2002 book.)

There has been a lot of work recently on the existence of diachronic norms for belief. I think I’ll start calling the view that there are such norms, and they are primarily norms of persistence, the Humean view. It has a better claim to being genuinely Hume’s view than most views I call Humean!

3 Replies to “Belief and Stability”

  1. Thanks for the shout-out, and the references Brian! I’d like to follow-up the Loeb and Holton—-can you give me a pointer as to where in RH’s work to look? (Looking down his paper list, I’m thinking “Rational resolve” looks a likely place?)

    One thing that’s in the spirit of the project of the paper for the Caret/Hjortland volume is to ask about the source of norms of persistence—-and I don’t really do that there. It seems easier to think of pragmatic as opposed to epistemic reasons for persisting in beliefs. So that’s one thing I’d like to look for in the wider literature.

  2. Hi. This post seems like something I’d want to understand, even though I don’t know what the technical terms mean. From a layman’s perspective, it seems to make no sense.

    >In the limiting case, consider a situation where one simply moves from one moment to the next, with no new input or reflection. It would be bizarre to change ones (non-indexical) beliefs in such circumstances.

    I have degrees of belief. There is probably not a tiger nearby. If someone in the room I am now tells me there is a Tiger within 100 feet of us, that will probably somewhat make me think it is more likely there is a tiger nearby than I had. If someone opens a door and there is what appears to be a Tiger on the other side of the door, I will think it even more likely a tiger is nearby. Is this not so?

    Because an apparent tiger on the other side of the door counts as some evidence that a tiger is nearby, it must be that the apparent absence of a tiger if someone in the room opens the door counts as evidence that there is not a tiger nearby.

    And yet, there is no essential difference between the case where someone opens the door and no one opens the door. That there is no scratching sound at the door, or scream outside of it, etc., counts as evidence that there is no tiger even if “one simply move[d] from one moment to the next.”

    Indeed, regarding “with no new input or reflection,” one sometimes reflects and sometimes does not reflect. Whichever one is doing counts as evidence for all sorts of things directly, and must count as evidence at least between the relative likelihood of overarching scenarios, e.g. the probability one is hallucinating.

    Regarding physics and the nature of time, I don’t think it has meaning absent movement of matter. What would it mean to say that, hypothetically, a year passed but no objects, their atoms, quarks, space itself etc. changed at all? Nothing.

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