Yesterday I discussed arguments for the broadly materialistic principle that "we can characterise thought and understanding entirely without reference to any external object". But let's not confuse that with materialism itself, and certainly let's not confuse it with crude materialism. I am concerned with rejecting the sort of anti-materialist argument that we cannot characterise a thought unless we can specify what it is a thought of, and rejecting an argument against something is obviously not the same as an argument for something.
As for 'crude' materialism, that is a perfect example of the kind of bad, sophomoric philosophy which it is the job of good philosophy to correct. There's a wonderful page full of it here. Someone, probably with an education entirely confined to the hard sciences, has the insight that people are made entirely of atoms. Molecules are made of entirely atoms, ergo humans are molecules. Materialism of the crudest sort. What's wrong with it? Well, I am not sure it is even scientifically correct. Molecules are arrangements of atoms in certain bonding relationships that hold only at the atomic level. So even DNA is not a molecule, but rather a pair of molecules held tightly together. The relationship that ties the heart to liver, and the liver to the brain is not an atomic one. Or is a molecule a set of atoms in any relationship whatsoever? Then a city is a molecule, the Earth and the Sun are molecules, the Earth and the Sun together are a single molecule, the whole universe is a single molecule. That is no help whatsoever.
Even if it is scientifically correct (I'm no expert), how does the insight help? We want to explain the nature of money, for example. Now money is an arrangement of atoms – either atoms of pound notes, or coins, or bond 'paper', or their electronic correlates in the general ledger of a payments system. But how does that help explain money? It is the job of the sciences of economics and finance to do that. How does the science of atoms and thermodynamics help us here? That's not to say that, once we have perfected those sciences, we could give a more complete, but vastly more complicated explanation in terms of atomic theory. My point is that the insight – that things are composed of atoms – does not help us explain economics, aesthetics, history etc.
Sometimes a crude materialism of this sort is used to justify malicious actions. "OK I lied to you, but I am only a collection of atoms, and concepts like good and evil and being 'wrong' are not appropriate to collections of atoms. Therefore what I did was not wrong". Which reminds of the story (I can't remember where I read it), of the man who was about to be executed for murder the next day, and pleaded to the king for clemency. "I could not help my actions, I was determined by my nature and by the stars to commit these evil deed, it was all predestined". To which the king replied "I forgive you. I also forgive the man who is to execute you tomorrow".