THE 'YOU CAN'T PROVE IT EITHER WAY" MOVE A bit from draft for my DK book Companion Guide to Philosophy

(this was cut down in published version)

Reasonableness comes in degrees (B heading)

INTRO: Beliefs can be more or less reasonable. There is, if you like, a scale of reasonableness on which beliefs may be located. Unfortunately, that reasonableness is a matter of degree is often overlooked. It’s sometimes assumed that if neither a belief A, nor its denial B, are conclusively “proved”, then the two beliefs must be more or less equally reasonable or unreasonable. As we will see, this assumption is false.

MAIN TEXT. Some beliefs are very reasonable indeed. It’s reasonable for me to believe that the orange on the table in front of me exists, because I can see it there. It’s also reasonable for me to believe that the tree outside my house still exists, because it was there when I last looked, and I have no reason to suppose anyone has removed it in the meantime. And it is reasonable for me to believe that Japan exists, despite the fact that I have never actually been there. I possess an enormous amount of evidence that Japan exists, and hardly any evidence to suggest it doesn’t.

            Of course, despite being highly reasonable, these beliefs could still conceivably turn out to be false. Perhaps the orange I seem to see before me is an hallucination. Perhaps the tree in my garden has secretly been removed by pranksters. In the film The Truman Show, there is a conspiracy to dupe the main character into thinking he is living his life out in the real world when in fact everything around him is part of a carefully managed TV set. Even those he believes to be his closest relatives are, in truth, merely actors. Perhaps I am the unwitting victim of a similar complex conspiracy to make me believe Japan exists when in fact it doesn’t.

            So let’s acknowledge I might be mistaken in holding these beliefs. Certainly, I cannot prove them beyond all doubt. But of course, this is not to say these beliefs aren’t eminently reasonable. They clearly are. They lie towards the top of the scale of reasonableness.

            At the bottom of the scale lies the belief that faeries and goblins exist. This is a very unreasonable thing to believe. There’s no good evidence these tiny folk exist and plenty of evidence that they are fictional. Still, it does remain a remote possibility that these fairy-tale folk exist. We can’t prove beyond all doubt that they don’t.

            Around the middle of the scale of reasonableness lie beliefs which are neither highly reasonable nor highly unreasonable. Take the belief that there are intelligent life forms living somewhere out there in the universe. True, we have no direct evidence of any such extra-terrestrial intelligence. On the other hand, we know that intelligent life has evolved on this planet, and we also know that there are countless other similar planets out there. So it’s not particularly improbable that there is intelligence out there somewhere.

Beliefs can change their position on this scale over time. A few decades ago, belief in electrons was fairly reasonable. Given the additional scientific evidence that’s since been discovered, it is now very reasonable. At one time belief that the world is flat was perhaps not so unreasonable. It’s now very unreasonable indeed.

The scale may also vary from one person to the next. It’s very reasonable for me to believe there is an orange on the table in front of me, because I can see it there. Perhaps it’s not quite so reasonable for you to believe there’s an orange there. After all, you can’t see the orange. You simply have to take my word for it.

Of course, it’s contentious where some beliefs lie. Take belief in the existence of God, for example. Some consider belief God is no more reasonable than belief in fairies. Others believe it is fairly reasonable – at least as reasonable as, say, belief in extra-terrestrial intelligence. Those who claim to have had direct experience of God, or who think miracles and so on constitute fairly good evidence that God exists, may place belief fairly high up on the scale (even while acknowledging that their belief is not “proved”).

The “You can’t prove it either way” move

Having set up the scale of reasonableness, let’s now look at a common mistake people make when assessing the reasonableness of a belief.

Sometimes, when someone has been given very good grounds for supposing a belief B belief is false, they respond by saying “But you can’t prove B is false, can you? B might be true!” They think this shows belief B is still pretty reasonable – perhaps even as reasonable as the belief that B is false.

Here is an example. Suppose you have just provided Ted with excellent grounds for supposing his belief that there are fairies at the bottom of the garden is false. Ted responds “But you can’t prove there are no faeries down there, can you?”, as if that showed that his belief is, after all, pretty reasonable – perhaps even as reasonable as yours.  Now perhaps you can’t prove beyond all doubt that there are no faeries. It’s just possible that you’re mistaken. Still, it’s hardly likely, given the evidence. On the available evidence, Ted’s belief remains downright silly.

Here’s a philosophical example. Even if we cannot conclusively prove either that God does exist or that he doesn’t, it doesn’t follow that the belief that God exists is just as reasonable or unreasonable as the belief that he doesn’t. It might still be the case that there are very good grounds for supposing God exists, and little reason to suppose he doesn’t. In which case it is far more reasonable to believe in God than it is to deny his existence. Conversely, there might be powerful evidence God doesn’t exist, and little reason to suppose he does. In which case atheism may be far more reasonable. We should not allow the fact that neither belief can be conclusively proved to obscure the fact that one belief might not be far more reasonable than the other.

Unfortunately, theists sometimes respond to atheist arguments by pointing out the atheist has not conclusively proved there is no God, as if that showed belief in God must be fairly reasonable after all. Actually, even if the atheist can’t conclusively prove there is no God, they might still succeed in showing that belief in God is very unreasonable indeed – perhaps even as unreasonable as belief in fairies.

Pointing out the absence of “proof” against a belief does not show that the belief is, after all, at least fairly reasonable.

IMAGE OF A RECTANGLE, LEFT HALF RED MIDDLE HALF WHITE AND RIGHT HALF GREEN. IN LEFT-HAND RED HALF PUT “DISPROVED” IN RIGHT HAND GREEN HALF, PUT “PROVED” IN MIDDLE BOX PUT “NEITHER PROVED NOR DISPROVED”. Caption: Rather than arranging beliefs on the scale of reasonableness, we might sort them instead into the three boxes “proved, “disproved” and “neither proved nor disproved”. We may then lose sight of the fact that the beliefs in the middle box may still differ dramatically in terms of their reasonableness.

The ambiguity of “proved” People often talk about a belief being “proved”, “not proved”, “disproved”, and so on. But what does “proved” mean here? It can mean a variety of things, including:

Proved beyond all possible doubt

Proved beyond reasonable doubt

Shown to be certain

Shown to be almost certainly true

Shown to be very probably true

Notice that people often talk of “scientific proof” despite the fact that most, perhaps all, scientific claims are open to at least some doubt.

When using the term “prove” it is important to be clear what you mean. Take for example, the claim that we cannot “prove” God exists. It might be true we can’t “prove” beyond all possible doubt God exists. But then perhaps we can still “prove” God exists in the sense we can still show his existence to be extremely probable, or to be at least beyond reasonable doubt. Conversely, even if we can’t “prove” beyond all doubt God does not exist, it doesn’t follow that we can’t show his existence to be extremely improbable. We should not allow loose use of the word “proved” to obscure these facts.

IMAGE OF GOD. Caption: Where should we place “God exists” on the scale of reasonableness? Indeed, should belief in God appear on the scale at all (but if it doesn’t appear on the scale, why not?)

NB. Nothing I say here should be taken to commit me to evidentialism - the view that a belief is reasonably held only if it is supported by evidence. Evidentialism is probably false. See here.