Saturday, February 21, 2009

Skepticism, Rationality and Default Trust

Intellectual virtue lies between the two extremes of dogmatism and radical skepticism. The irrationality of dogmatism is generally appreciated; less so the irrationality of radical skepticism (at least among my intro M&E students!). Let's attempt a remedy.

The global skeptic insists that we should question everything, trusting nothing: apparent perception, memory, "rational intuition", even methods of reasoning -- anything that can be doubted must be suspended from our minds and considered 'guilty until proven innocent'. The obvious problem with this stance - if followed assiduously - is that it entails rejecting everything, leaving one with no mind at all. This is the crucial point: just as a pure 'blank slate' cannot learn from experience, so must we rely on various assumptions if we are to learn, reason, and act rationally at all.

That's not to say we should dogmatically refuse to question our beliefs and practices. It's just that we cannot question them all at once. Any individual belief or assumption may be tested in light of the other things we (provisionally) take to be true, and revised if some incoherence is found. But we have to reason from the beliefs we have -- as Neurath famously put it, our mind is like a ship at sea, and even as we replace a faulty plank we must trust our weight to others.

The mere fact that those other beliefs can likewise be questioned does not suffice to show that we can't reasonably accept them (again, provisionally) in the meantime. The skeptic's claim to the contrary is itself a questionable belief, and not one we have any reason to accept. (It may seem intuitive at first, but once we fully understand the implications of this claim, it would be crazy to accept it -- or so I argue.)

To begin with, it's worth emphasizing that global skepticism is self-defeating, insofar as it implies that we should not trust its recommendation to trust nothing. Or, as Railton writes (in 'How to Engage Reason', Reason and Value, p.186):
Hume observed that [the sceptic] displays a touchingly unsceptical attitude towards the power of argumentation and his own powers of thought and memory. We might add: toward his own command of language and the content of this thoughts. Remove this default confidence, and he can no more declare his words to be 'giving an argument for scepticism'--an intentional action--than 'giving a recipe for haggis' or 'scat-singing without a tune'.

Hence my earlier claim that one who truly internalizes global skepticism is no longer capable of intentional thought or action at all. To accept global skepticism is to forsake any hope of rationality. It is the ultimate intellectual black hole. Railton (p.187) draws an important lesson:
Default trust, however 'blind', is not inherently blinding. On the contrary. If the sceptic trusts his ability to speak English and draw the conclusions demanded of his premisses, and I trust my own appreciation of his argument, we will both see (no longer be blind to) a problem that I have in defending my beliefs: Where I previously had hoped to be able always to have a reason for whatever I believe, taking nothing 'blindly' or 'without reason', I now realize that this hope is impossible--some things cannot, without regress or circularity, be argued for.

I trust the reader will by now agree that global skepticism is a non-starter, as any rational agent must take some things 'on trust' if they are to be capable of reasoning at all. Still, one might ask, what of slightly restricted forms of skepticism? Couldn't one consistently hold the more traditional skeptical view that it's just our sensory experiences and/or inductive practices that shouldn't be trusted? The traditional skeptic is willing to trust in reasoning as much as anybody is. They simply have different expectations about the external world (or "affirm a different prior") from the rest of us. In particular, they hold that all possible worlds are (a priori) equally probable, whereas we anti-skeptics consider some (perhaps simpler or more regular-seeming) distributions of properties across space and time to be more probable than others.

Sure, there may not be anything inconsistent about traditional skepticism, so defined. (Though such a skeptic has no reason to expect that they will continue to exist long enough to finish their thought.) But nor is there much reason to accept it, or indeed to find it any more credible than the claim that the world just came into existence 5 minutes ago. Admittedly, traditional skepticism is motivated by a premise that seems plausible at first glance, namely: "the reasonable 'default' view is to start off by assigning each possible world an equal probability of being actual." That sounds fairer and more reasonable than an a priori bias in favour of, say, worlds where memories are typically true--representing times and events that really did happen. But I suspect the intuitive plausibility of this is an instance of us being misled by overly-abstract principles. When we consider every more particular judgment or knowledge-attribution we are inclined to make, is it really plausible to think that the one abstract principle is more credible than all our conflicting particular judgments - and practices - combined? Colour me (cough) skeptical.

Upon reflection - in light of our actual beliefs - it seems we have most reason to reject the skeptic's principle. Though it seemed plausible at first, it is inconsistent with other claims that most of us find much more plausible. Here's another: rational agents should learn from experience. Skeptics -- even of the merely 'traditional' variety -- can't. As Railton writes (in 'Rational Desire and Rationality in Desire'):
It is well known that in order to learn about one's environment (whether one be human, animal, or teachable computer) it is not enough to have ample sensory input and plenty of memory registers to fill. The learner must also bring some expectations--such as expected dimensions of similarity (the "implicit quality space"). Otherwise, experience will simply accumulate in its infinite diversity, and all experiences will be equally relevant or irrelevant to one another. No lessons will be extracted.

Carnap gave an elegant demonstration of this point within the theory of logical probability. He asked us to consider a confirmation function that began (sensibly, it would seem) with no "prior bias", i.e., that assigned the same non-zero probability to every possible state of the world (what he called "state descriptions"). This function would, even given indefinitely large amounts of information about past states of the world, still assign the same probability to every logically possible way of extending this history into the future. In a fundamental sense, it could not learn from experience.

So I think it's pretty safe to conclude that (even the traditional form of) radical skepticism isn't rational. There's no guarantee that the rest of us are any better off, of course, but at least we have a chance. We do the best we can -- and we're yet to see any good reason to think that some other way is better.

One may be left feeling unsatisfied: the best we can do may not seem good enough. But since turning to skepticism is even worse, it seems we will just have to learn to live with tentatively trusting in the reliability of our perceptions, despite the uncertainty of it all. At least we can learn such things -- and that is something to be thankful for.


  1. Richard, this is interested stuff, but I found the line of argument a little fishy at one or two points.

    "we have to reason from the beliefs we have"

    If your argument relies on this thought, haven't you defeated scepticism only by effectively conceding the debate? On this (coherentist) view, we are only able to draw connections between our beliefs, hoping that this belief system correlates with how the world is. One would think that exactly what the sceptic asserts is this kind of unbridgable gap between our beliefs and the world.

    "traditional skepticism is motivated by a premise that seems plausible at first glance, namely: 'the reasonable 'default' view is to start off by assigning each possible world an equal probability of being actual.'"

    I found this a little puzzling. Does the sceptic really have a positive belief that all eventualities are equally likely? Surely the sceptic is the person who withholds belief, not one who puts equal belief in everything.


  2. I don't think that global skepticism is self defeating. One can believe that all of one's belief generating faculties are faulty. We can even use those faculties to come to this conclusion; demonstrating their untrustworthiness on the assumption of their trustworthiness is demonstrating their untrustworthiness. Does this mean that the skeptic should abandon his faculties? Not unless he has anything better (though of course he has no reason not to abandon them either). The reasoning of the skeptic need be no different than that of the dogmatist -- what characterizes the skeptic is his humility.
    Likewise, I think that the skeptic has the same expectations about the distribution properties, they just realize that there is no good reason for that expectation.


  3. Derek - "demonstrating their untrustworthiness on the assumption of their trustworthiness is demonstrating their untrustworthiness"

    If one has competently carried out the 'demonstration' (drawing valid inferences, etc.), but a truly global skeptic will necessarily doubt whether they have actually succeeded in showing any such thing. For all they know, perhaps all they really ended up doing was not 'giving an argument' at all, but rather 'giving a recipe for haggis', as Railton puts it. (So I think you're still underestimating just how much has to be assumed -- and continue to be assumed -- in order for one to be capable of anything recognizable as thinking at all.)

    "I think that the skeptic has the same expectations about the distribution properties, they just realize that there is no good reason for that expectation."

    Such 'humble beliefs' are demonstrably incoherent. One can believe that P, or that such belief is unwarranted, but not both. Rational reflective belief entails thinking oneself lucky.

    Alex - I took the global skeptic to be one who withholds all belief. But once we reject such a general requirement, how is the TS going to motivate their more limited suspension? Looking at the arguments skeptics standardly give, they seem to be relying on a kind of principle of indifference ("your experiences are equally compatible with the BIV world as with common-sense realism, so you shouldn't give common-sense realism any greater credence"). I guess you could model this as having no prior at all, rather than a flat prior, if you like. It comes to the same in the end: such an agent is incapable of learning from experience.

    "haven't you defeated scepticism only by effectively conceding the debate"

    Nope. The debate I'm concerned with is over whether we can have justified beliefs (not whether we can show it to the skeptic's satisfaction). I hold that our beliefs can be (and, indeed, typically are) justified, which is precisely to deny 'skepticism' (as I use the term).

    It's true that I accept that there is a "kind of unbridgable gap between our beliefs and the world". But I don't see how that is in itself a skeptical thesis. (It is merely a claim the skeptic uses, in conjunction with other premises I reject, to argue for their view.)

    Of course, you may be using the term 'skeptic' in some broader sense that includes, say, me. Then it's just a terminological dispute. So forget the word. The crucial point I'm arguing for is that we aren't rationally required to suspend our beliefs or consider them "unjustified" -- at least, not for the kinds of reasons that skeptics offer. Stronger still: it would be positively irrational to accept the skeptical principles (as I defined them).

    The rational agent is open-minded but not, in Derek's sense, "humble".

  4. I think that it is ok to hold a belief and believe that that belief is unjustified. Most of things we believe are both true and unjustified (at least in the sense the skeptic is interested in). As I understand it, you take the problem with such a position to be that it requires simultaneously holding a belief that something is true and that it is unlikely to be true. I think that there is a problem with conflating justification with probability; there is no interesting notion of probability for justification (in the sense that the skeptic wants -- there may be in the sense that Stich wants) to correspond to. And there is nothing incoherent about believing something and thinking one therein unjustified.

    I would suggest instead a principle that a reflective agent should not believe anything such that he has better grounds for believing something contrary. But the skeptic has no better grounds for believing otherwise, since he has no grounds for any of his initial beliefs.

    If we accept that one's beliefs can provide good reasons for further beliefs even if they are unjustified, then the skeptic might claim to have good reasons to be a skeptic. He does not know that they are good reasons but he believes them to be.


  5. Richard,

    My worry is less about your use of the term 'sceptic', and more about your use of the term 'justified'. You try to defeat the sceptic by showing that many of our beliefs are justified. But I worry that you've shown this only by lowering the standard for justification. What the sceptic wants is some reason to think that your beliefs are true, not reason to think that they sit well with the other beliefs you have.

  6. Alex - I think you've misunderstood my argument. I did not take myself to be "showing that many of our beliefs are justified." (For all I've said here, it remains possible that most of our beliefs are unwarranted. I think that would be true of the anti-skeptical BIV-believer, say, who might echo all I've said here in support of his anti-skepticism. That does nothing to justify his BIV-belief.) I do hold that many of our beliefs are justified, of course, but one can't give any non-question-begging positive argument for such a fundamental claim. My ambitions here were more modest: namely, to give a largely defensive argument to show that the skeptic hasn't established that our beliefs are unjustified -- his arguments rely on premises that we have every reason to reject. (That's the positive part of my view: we certainly shouldn't be skeptics. The rational agent is a fairly confident believer. But it's a further question whether ours are the confident beliefs to have! Still, we may as well assume so.)

    All this raises complicated issues regarding the intersection between first-personal ("instruction manual") advice and third-personal assessments of objective warrant, which I should probably clear up in a new post sometime.

    Derek - very interesting! But what sense of "justification" do you take your skeptic to be interested in? (Perhaps they do not really disagree with me.) I'm concerned with a notion of objective warrant that is tied to rational subjective probabilities (roughly: what credence a perfectly rational agent would give to P given your evidence E. Or their prior judgment of the conditional probability of P|E. See here for the argument that a perfectly rational agent must have complete and precise credences.)

    If claims of justification aren't closely tied to claims of (likely) truth, I lose my grip on what you're even talking about, or why the absence of this mysterious property is something that should bother me.

    But here's a way to bring out the incoherence of believing oneself unjustified (in the usual sense of the term, as I understand it). Moore-paradoxical assertions:

    "P, but I don't know that P."
    "P, but there's no good reason to think that P."
    "P, but the evidence doesn't really support any such claim."
    "P, but my belief-that-P is unwarranted."

    None of these sound (to my ear) much better than the traditional: "P, but I don't believe that P." All seem to involve a kind of incoherence, no?

  7. I don’t know how to explain the concept of epistemic warrant that I think the skeptic is interested in, though I can point out examples. It is the sense that Kant and Russell were interested in, and Quine and Stich are not. In any case, the skeptic I am imagining will deny that there is a unique rational set of priors. He will claim instead that opposite conditionalizations are rationally permissable. He has come to certain conclusions about the way the world is, but one cannot critique him on the grounds of rationality for coming to opposite conclusions.
    This does not mean that his choice of priors is arbitrary. Given the way the world is, his choice is the right one. However his recognition of this fact is not independent of his use of his preferred modes of thinking. A sort of circularity ensues. This circularity means that his beliefs are ultimately ungrounded (and thus lacking warrant). But that doesn’t mean that they are inconsistent.

    With regards to the Moorean statement, I think you are right that there is something strange about saying

    P, but my belief in P is

    But it is not nearly as strange as saying

    P but I don’t believe that P.

    People do have beliefs that they recognize are unwarranted and are nevertheless willing to assert them.

    There is a god, but his existence must be taken on faith.

    The problems with asserting unwarranted beliefs are largely pragmatic and not, I think, epistemic.


  8. "However his recognition of this fact [that his beliefs are correct] is not independent of his use of his preferred modes of thinking."

    That's true on any account. (It's certainly what Railton - and, derivatively, I - accept.) Where we part ways with the skeptic is in your next claim, that this unavoidable subjective circularity somehow entails that one's beliefs are objectively "lacking warrant". That's precisely the skeptical principle that I deny anyone should accept on reflection. (But this may just be a point of intractable disagreement.)

    "There is a god, but his existence must be taken on faith."

    There are two possible interpretations of such claims. (1) The simple view of 'faith' you seem to be assuming, whereby it means something like 'unjustified belief'. Or (2) one might have a more complex view of 'faith' according to which it can warrant beliefs (and, in particular, render a proposition more apt for belief than its negation).

    On the second interpretation, there's no problem. On the first interpretation, the assertion strikes me as a plainly incoherent. Sometimes people are willing to assert incoherent things. But this reflects poorly on them, not well on the things they say.

  9. Hi Richard

    This is a bit tangential but I want to press you a bit on your comments about faith

    “There are two possible interpretations of such claims. (1) The simple view of 'faith' you seem to be assuming, whereby it means something like 'unjustified belief'. Or (2) one might have a more complex view of 'faith' according to which it can warrant beliefs (and, in particular, render a proposition more apt for belief than its negation).”

    Faith as normally defined by people like Aquinas, etc is that it believes something on the basis of authority and not on the basis of an argument or proof for the proposition in question. So you are correct that there is nothing about the concept which implies lack of justification unless you equate justification with argument.

    What interests me however is you seem to actually sketch a method that lends itself to faith so defined in a certain way. You state

    “that's not to say we should dogmatically refuse to question our beliefs and practices. It's just that we cannot question them all at once. Any individual belief or assumption may be tested in light of the other things we (provisionally) take to be true, and revised if some incoherence is found. But we have to reason from the beliefs we have -- as Neurath famously put it, our mind is like a ship at sea, and even as we replace a faulty plank we must trust our weight to others.”

    This seems to suggest that a religious believer who believes something on faith can provisionally accept his beliefs ( even if not proven) provided they cohere well with his other beliefs. In otherwords it seems to entail that some form of disproof (in the form of incoherence) is necessary for rational belief as opposed to proof for them.

  10. Right, I wouldn't read too much into this point though -- in some cases 'default trust' might be more easily defeated than others. (I think there are pretty decisive reasons to reject religious belief, for example, though this isn't the place to discuss that further.) So this certainly isn't any kind of blanket 'anything goes' defense of belief.

  11. Richard

    I was not suggesting that “anything goes” on your position, and I was assuming that the theist would have to address relevant defeaters. ( and unsurprisingly I do not think your arguments against theism are very decisive at all but as you say that’s something to discuss elsewhere). But your position does undercut one very influential way of criticising theism, that is the position that theism is irrational if there is no proof ( i.e a good deductive/inductive/abductive evidence for theism from premises that all rational people are compelled to accept) that God exists.

    Your position suggests the theist is prima-facie justifiably believe in God without argument. What the rationality of theism turns on is not arguments for the existence of God but the arguments against them. I agree ( for different reasons, notably those suggested by Plantinga) but this is a fairly significant conclusion, It certainly undercuts the very common type of religious scepticism that claims atheism is justified because the arguments for God’s existence fails and that in the absence of argument for Gods existence the default position is atheism. This is perhaps the most common type of religious scepticism.

  12. I disagree. Everything I've said here is compatible with holding that atheism is the default position on grounds of parsimony or the like. (The standard objection you talk about is best understood as pointing out that your initial 'default trust' in your religious beliefs is defeated by Ockham's Razor, leaving atheism the new default position.)

    Rather, my arguments here merely suggest that one had better not object to theism on the general grounds that (all) beliefs are unjustified by default -- a claim, note, that would apply equally to atheistic belief. So at most this undercuts a kind of (transparently silly) argument for agnosticism. But I think you're strictly mistaken to see anything of significance here regarding standard atheistic arguments.

  13. Richard

    Thanks for your comments.

    First by taking about “new” default position I suspect you are in fact conceding the point some what. The theist is rational in starting with belief in God, it’s only after some sound argument is given (you think an appeal to ockhams razor would be such an argument) that he is rationally required to give it up. It therefore depends on arguments against God’s existence not the absence of arguments for his existence that matter.

    Second, I am not sure Ockham’s razor would work here. Ockham’s razor talks of not multiplying enties beyond what is necessary for explaining the data. It’s use seems to already presuppose a distinction between beliefs which one accepts by default ( the data) and others which are justified by an abductive inference from this data. Because they get their warrant by inference to the best explanation Ockham’s razor applies. But the whole question being asked is whether theism is a default belief or one justified by some form of inference. I wonder if there is a kind of question begging going on in here.

    In any effect couldn’t a similar move me made with any ontological commitment. I start with a default trust in my belief in the past, however given Ockham’s razor, I have to prove the past exists. I start with a default belief in the physical world, ockhams razor could be used to demand proof for that. Or perhaps more poignantly, I start with default moral beliefs, such as raping women for entertainment is fun is wrong, given Ockham’s razor the new default is that I should assume that these moral properties do not exist.

    I don’t know that you can prize religious scepticism apart from general scepticism as easily as you suggest.The moves and countermoves are not that different.


  14. Now that sounds suspiciously like the "anything goes" argument. At the end of the day, I do think there are good reasons for believing in the past, etc., but not in the various supernatural beings people have imagined. But it would take us too far afield to pursue this disagreement further. (And I grant that a certain degree of question-begging is unavoidable once one gets down to fundamentals.)

  15. Richard

    Yes I think discussing this further would take us off topic. I will simply say two things. First, I think that belief in God is for many theists like belief in other minds in certain important respects.

    Second, I don't think this is the "anything goes argument" you critqued. I think there have been quite sophisticated defences of this position by people like Plantinga, Alston, etc which are much more plausible than the one you cited. But again that will take us off topic into other issues.


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