To ask a question our illustrious leader, Alexander George, has several times asked here: What's meant by "prove"? If what's meant is what's ordinarily meant by "prove", then it's not clear that a single person on this planet can prove human beings evolved from apes. Nor can anyone prove that the Loch Ness monster does not exist. But that simply doesn't mean that there can't be good reasons to believe that human beings evolved from apes or that the Loch Ness monster does not exist. There can be, and there are.

Now what exactly that has to do with the rest of the question is not yet clear. But have a look here http://plato.stanford.edu/entries/pascal-wager/ for some thoughts (not mine).

It sounds as though you're giving a version of Pascal's Wager. One version of that argument runs along the following lines (whether or not this is exactly what Pascal had in mind): If God exist and I believe, I'll get infinite bliss. If he exists and I don't believe, I'm damned. But if God doesn't exist and I believe, I lose little, if anything and if he doesn't exist and I don't believe, I don't gain that much. Since belief potentially gains me much and loses me little, but since disbelief potentially gains me little and loses me much, I should believe.

One problem, of course, is whether skeptical people can actually get themselves to believe. Pascal thought they could by going to mass, taking holy water and the like. Let's suppose he's right. What's the downside?

One famous difficulty is the "many gods" objection. Which version of God do we believe in? What sorts of actions should we perform? Should we be Christians? What if there's a God who sees that as an unacceptable form of thinly-disguised polytheism? Should we reject Christianity? Millions of Christians see that as a sure path to damnation. And on it goes.

If the argument is that we should back the right horse in order to get a shot at paradise and avoid the fiery pit, then the problem is that we don't know which horse to pick. If we bring in general theological/philosophical considerations to decide which religious hypotheses are most plausible (or least implausible), then we may well end up deciding that a God who wouldnm't damn people for their honest opinions is at least as plausible as some wrath-ridden sort with inscrutable views. But in that case, the Wager loses its force.

This isn't to say that what some people call "pragmatic reasons" for religous belief have no force. William James's "The Will to Believe" makes a better case, though what James is arguing is often misunderstood. Suffice it to say, however, that it would be very difficult to show that a rational person couldn't be a non-believer; pragmatic arguments simply aren't up to that task.

Only if you define "rationality" in a way that makes it opposed to emotion. But for a lot of reasons, that would be a dubious definition.

For one thing, we have reason to believe that intelligent decision-making isn't disconnected from emotions. There's been a good deal of work on this topic by philosophers and scientists, but one well-know place to start is with Antonio Damasio's book Descartes' Error. It turns out that the emotional centers in the brain have an important role to play in helping keep us on the rails.

We can add: other things being equal, it doesn't sound rational to choose a life that makes it less likely that we'll be happy and fulfilled. But for most of us, a good deal of what makes life meaningful is bound up with our emotions. In a perfectly obvious sense of "rational," it's rational to seek love, let ourselves cry in the face of tragedy and open ourselves to joy. A concept of "rationality" that ruled all this out would be poor and perverse.

Good question. My own view is that what happens in the long run is irrelevant to the rationality of betting (or in your case not betting) according to the odds in the single case. I think that it is a basic principle of practical rationality that your choices should be guided by the probabilities and that, surprisingly, there is no further justification for this.

A first point. You say 'over many trials you would lose out'. Well, if you are talking about a finite number of trials, that's not guaranteed. It is possible--indeed there will be a positive probability--that in a finite number of trials you will win even if you bet against the odds. All we can say it that the probability of winning over many trials is low. So now we are just back with the original problem. Why is it rational to avoid doing something just because the probability of success is low?

Does the situation change if we think about an infinite number of trials? Well, it's not even obvious that you are guaranteed to lose if you bet against the odds an infinite number of times. Of all the infinitely many sequences of results that might happen, there's a non-empty (indeed infinite) subset of sequences on which you win in the infinite long run. True, there is a 'zero probability' of any such sequence, even thought they are all possible (that's a nice puzzle in itself). But why take that 'zero probability' to be an argument for betting against these perfect possible sequences? Once more, this looks like the puzzle we started with.



Anyway, isn't there something odd from the start about long-run justifications of betting with the odds? Why is it an argument against betting on a 'six' now that something bad will happen if I do this lots of times (or even worse if I do it infinitely many times)? In the long run we will all be dead, as Keynes said.

Suppose I am a feckless fellow with no concern for tomorrow--I need some money now. Even so it is surely rational for me to bet with the odds. But you can't persuade me of this by saying that I need to bet with the odds in order to win in the long run. I don't care about the long run.

The more I think about it, the more it seems to me that betting with the odds is a basic principle of rationality, with no further justification.

I don't know the context of this claim, nor why Dawkins thinks---I take it he does think this---that no-one has any "evidence" for religious belief. Most theistically inclined epistemologists of religion, in the analytic tradition, anyway, think we do have certain kinds of evidence for belief in God. Dawkins might not find the evidence impressive, or he might disagree as to the evidential facts themselves, but it would be a parody of religious faith to think people believe on absolutely no basis. Just for example, suppose one is some kind of coherentist. Then you might think belief in God forms part of an overal "theory" of the world, and the evidence one has for it is that this theory is coherent, more successful than alternative theories, etc. You've got the same kind of evidence for your belief in God, ultimately, as for anything else you might believe, though belief in God, in such a system, will be deeply embedded, like very high-level theoretical claims, rather than towards the periphery, where experience impinges upon it more directly---to borrow some imagery from Quine.

But anyway, yes, if something is (forget about can be) asserted on absolutely no basis whatsoever, then, well, the person doing the asserting might as well just be making stuff up, and we can safely ignore them.

I don't believe in them myself, though I'd be quite willing to be convinved that some of them are true. However, the story you tell illustrates a typical difficulty of these accounts: we might grant that your in-laws saw something, but what was it?

The acronym "UFO," of course, stands for "Unidentified Flying Object." And that's what we have if we take your in-laws' story at face value. We certainly don't know that whatever it was came from outer space, as they used to say.

Of course, some stories say more. As you point out, we get tales of abduction, strange beings and the like. Apparently many of the people who make these reports seem otherwise sane and normal. Do we know that what these people say isn't so? I wouldn't say that we do. After all, it's surely possible that there is intelligent life elsewhere in the universe, and that some of it has made it to where we are. But many of the cautions that the 18th-century philosopher David Hume applied to miracle stories seem to apply here. People are often attracted to the strange and exotic, and sometimes prefer extravangant explanations to more humble ones. People also get have vivid dreams, get confused, misinterpret what they see, and sometimes they even lie. There are many possible explanations for the reports of alien sightings (as for sightings of ghosts, the Loch Ness monster, susquatches, the Virgin Mary and Elvis.) It's not clear that the mundane explanations are insufficient, and so until there's better evidence to the contrary, I'll rest with open-minded skepticism.

It might help to notice that there are distinct senses to "reasons for believing that P." The first sense (usually called "propositional justification" by epistemologists) has to do with there being some fact of the matter that would make it reasonable for me--that would justify me--in believing that P, should I happen to be aware of that fact. Hence, to use an example that has been used by others, the fact that there is smoke billowing out of the house (whether or not anyone is aware of it) is a good reason to think the house is on fire. The other sense is called "doxastic justification" by epistemologists, and has to do with what a person actually has, among his (other) beliefs, as justification for that person's belief that P. So I would be doxastically justified in believing that the house is on fire if I was aware of the smoke billowing out, and was also aware of the connection between smoke and fire.

It is a point of contention among epistemologists precisely what role justification (reasons, arguments, evidence) must play in knowledge and/or reasonable belief. For some, the fact that there is the right sort of causal connection between the knower and the known (even if the knower has nothing we would regard as doxastic justification) is enough. For others, what matters is whether the belief was formed or sustained in ways that reliably produce true beliefs--again, with or without the addition of doxastic justification. Even if we suppose that justification is required, it may well be (and indeed, seems almost certain) that what justifies us is distinct from whatever causes us to have that belief. Doxastic justification is generally understood as consisting in (other) beliefs one has, which provide evidenciary support to the belief they justify. But there are very good reasons to doubt that whatever entities (if they are entities) beliefs are will prove to be able to cause other beliefs. Presumably, the causal story will have to include lots of other entities and processes about which we are not (and perhaps cannot be) aware, in the way we can (at least in principle) be aware of the beliefs that provide doxastic justification for other beliefs we have.

I am sure you are right that there are certain beliefs that we acquire due to other reasons than reason. Wittgenstein is good on this in his On Certainty where he pokes fun at the idea that our most basic presuppositions could be based on anything at all. Perhaps he sometimes goes too far, since presumably there are situations where one's deepest held belief might be threatened by an argument or some piece of counter evidence. But it also might not. One of the entertaining aspects of listening to the news of the financial markets is the explanation for what is happening. If the markets decline and there is bad economic news these two facts are often linked. But equally often the news is bad and markets rise, and bull markets are defined as taking place when people climb a mountain of worry. There are of course important economic features like optimism or despair which come into play, and which may have little if anything to do with the actual facts on the ground. There are even some market players called contrarians who do the opposite of what everyone else is doing, a bit like some skeptics in ancient Greece who apparently had to be helped out of holes they fell into by their disciples since they tended to doubt the existence of such holes, their only evidence being what they apparently perceived. As skeptics, they systematically distrusted such "evidence".

As philosophers we should not perhaps be that concerned with why people actually believe in things, so much as whether they ought to believe them. My argument here might be designed to impress someone with whom I am having a relationship, but its success or otherwise in this regard is irrelevant to its validity.

I don’t think that the moral of your story would be that being right is just being in the majority, but it might be that we can’t know whether or not we are right. But even this fortunately won’t always be the case. Even if I can’t convince you, I may have good reason to believe that I am in a better position to know, because I have better evidence, because I am more expert in the area of our disagreement, etc.

But the tough case is where we disagree and I have no reason to think that I am better placed to be right than you are. And this does seem a common plight when the disagreement is in philosophy, though it is by no means limited to that area. Suppose that Hilary Putnam and I could lay out all the arguments that either of us can think of on some philosophical issue – say the existence of numbers – and still we end up disagreeing. It seems to me on balance and after much reflection that (say) numbers don’t exist, and it seems to him likewise that they do. What am I to do? Not only do we disagree, but he is so much smarter than I am! Of course he is not infallible, so he might have made a slip somewhere; but same for goes for me, in spades.

Since in philosophy it seems one can always find someone smarter who holds the opposite view, it is unclear whether we really can ever claim philosophical knowledge; indeed perhaps it is unclear whether we should ever have philosophical beliefs on the contentious issues. But the situation is complicated. Maybe as a philosophical community we do better, epistemically speaking, by holding and defending conflicting beliefs than if we all were in a permanent state of agnosticism. And maybe there are situations where I should privilege my own view over Hilary’s, where say I can rationally convince myself that, smart as he is, I can identify a mistake in reasoning that he has made in this case, even if I can’t convince him that it is a mistake.

Let me add two thoughts to this.

One may distinguish between theoretical and practical rationality. The former employs reason in the service of improving one's understanding and beliefs toward clarity and truth. The latter employs reason toward formulating and achieving ends. Much of the problem you highlight is illuminated by this distinction. Sometimes progress toward clarity and truth hampers our achievement of what we want and have reason to want. For example, when you have a dangerous disease, or find yourself in a life raft without water, you may employ your theoretical rationality to figure out what your chances of survival are. Employing your practical rationality, however, you might conclude that such researches would probably be depressing and would in any case distract you from your goal of getting over the emergency. The practically rational thing might be simply to assume that you can survive this and to throw your full effort into the most plausible option you've got. Beliefs that it is theoretically rational to form and to hold (because they are supported by a careful examination of the evidence) may not be ones that it is practically rational to hold (because forming and holding them will make it harder for you to achieve your reasonable ends). In your terms: When thinking th-irrationally makes you happy and thinking th-rationally brings you distress, then it may be pr-irrational to be th-rational.

We've seen that it may be pr-rational to eschew the path of th-rationality. As Derek Parfit (Reasons and Persons, p. 13) has interestingly discussed, it may also be pr-rational to eschew the path of pr-rationality. Parfit gives the example of a person who is being blackmailed with a threat of violence. The blackmailers are likely to give up when they conclude that the person is too pr-irrational to respond to threats. When the best way to bring the blackmailers to this conclusion is to actually be very pr-irrational, then it may be pr-rational to take a pill that makes one very pr-irrational.