For if my mental processes are determined wholly by the motions of atoms in my brain I have no reason to suppose that my beliefs are true… And hence I have no reason for supposing my brain to be composed of atoms.
-J.B.S. Haldane, “When I am Dead”
Every now and then, I like to toy with a little bit of philosophy. Recently I’ve been thinking about materialism, which is the belief that the universe consists of only physical material (atoms) and nothing else. All events – including human thoughts and emotions – are then determined necessarily by interactions between those atoms.
Materialism is often encountered in fields of science. As scientific knowledge continues to explain the physical workings of the world, our bodies, and even our brains, materialism seems ever more plausible. Before continuing, however, it’s important to clarify that materialism is a philosophical tenet, not a scientific one. The statement that nothing exists apart from matter is not a statement that can be tested experimentally, nor ever demonstrated through experience. It is inaccessible to the scientific method. There is a philosophical “leap” required to go from the scientific view that some things have an atomic explanation to the worldview that all things have atomic causes and no other cause.
J.B.S. Haldane was an influential biologist who made comments about materialism – one of his published comments is quoted above. It’s a quote that certainly makes me smile. It has a cheeky, circular, playfulness to it! But is there truth in it? Can such a simple argument dismantle materialism?
My personal knee-jerk response, is to invoke Darwinism. Haldane supposes that a purely material world couldn’t construct the organized sophistication of a brain that has “true” thoughts. But Darwin’s beautiful idea demonstrated how natural selection is certainly capable of creating sophisticated things. Maybe brains that thought “true” beliefs helped the bodies that they lived in to survive better. In time, through selection, our human brains got pretty good at believing “true” things.
But my Darwinian refutation isn’t enough. Haldane wasn’t saying that the world doesn’t have physical explanations. It does. And Darwin’s physical explanation is appropriate for our brains, just as much as for the rest of our bodies. What Haldane meant is that physical expanations aren’t the whole story.
To explain, I’ll try to re-phrase his argument differently. If materialism is true, then I could never know that it is true. That’s because, all of the “knowing” happening in my brain would be determined completely physically. And that doesn’t leave any room for what’s actually true to influence that which I know.
Wow, that was convoluted. Here’s an illustrative story. Suppose that I believe in materialism. My friend believes that immaterial ‘fairies’ exist, somewhere far away. If both our brains contain nothing but atoms, then we arrived at these beliefs necessarily, as determined by atomic interactions. Now consider those fairies. Do they exist? Because I’m a materialist, I don’t believe that they do. But I have no reason to judge that the atoms in my head somehow yielded a true belief, while the atoms in my friend’s head did not. What is truth to atoms? So as a materialist, I cannot say whether fairies exist. Or: as a materialist, I cannot say whether the immaterial exists. Or: as a materialist, I cannot be a materialist. Therein lies the contradiction.
I’ve been seeking to understand this elusive argument against materialism of Haldane’s for awhile. Even still, I eye it suspiciously, not confident that it holds water. What do you think? Can you see any difficulties?
You cannot say whether faeries exist, but the same reasoning which forbids you to say whether they exist likewise forbids those who claim they do exist from doing so. That is, those who claim faeries exist violate the same principle which you would have to violate in claiming that they do not exist.
Now add into this the information that there are an infinitely large number of positive claims which might be made, and that the fact that someone makes those claims in no way, by itself ,constitutes evidence for that claim, and given that it is obvious that the vast majority of those arbitrary possible claims must be false, (e.g. here are an infinite number of false claims: for a given coordinate in the universe, x,y,z, in whatever units you happen to like iterating over all possible coordinates, there exists an invisible half-zebra, half-mushroom creature who speaks Greek as it was spoken in 6000 BC at that location.) then we arrive at the conclusion that it is incumbent upon those making the claim to provide some evidence.
Also, I think that “reality” is defined by perceptions. That is, our senses are *authoritative* but not *reliable*. Our sense are *all we have*. Reality is *defined* by our senses in that respect. if some reality is posited which has some aspect which cannot be sensed, directly, indirectly, by any instrumentation, or at all, even in theory, then this posited “reality” is in fact, not reality — it is not real. By definition, reality must be, at least in theory, able to be sensed.
Comment by scaryreasoner — August 27, 2008 @ 1:18 am
I agree: positive claims require evidence. So my friend equally cannot say that fairies do exist. But if any proposition, whether positive or negative, leads to a logical contradiction, then it must be false. So in this case, the negative claim that the immaterial doesn’t exist precludes me from ever being able to know that it doesn’t. Haldane said that materialism “saws away the branch that it is sitting on”.
Now about all reality being able to be sensed. What about logic and reasoning? I think that rational thought (like the discussion that we are having now) leads to real insight. Further, I think the laws of logic (also the laws of mathematics) are actually part of the defining fabric of reality. But we cannot sense them – at least not with the five senses.
Comment by Jason Booy — August 27, 2008 @ 8:33 am