Hey, look, a philosophy post.
Over here, Bryan Norwood of Movement of Existence argues that reductive materialism must be false because it entails that there are no sociological effects, thus social circumstances only have causal efficacy if they can be successfully reduced to physical phenomena. He tries to use language as a counter-example, pointing out that the content of language is supposed to have some effect on behaviour (indeed, our entire science is based on this presumption). Furthermore, since the very science that underwrites reductive materialism must itself be based on language, the idea that language has no independent causal power is an absurdity.
This argument doesn't work, though I'm deeply sympathetic to the conclusion. First, the apparent causal efficacy of the content of language could be an illusion. That is, content seems to have effects to us, but this is just because of the interactions of all the quantum stuff in our brains. We can't help but believe that this is true, but it isn't, in reality. Second, it's not absurd that we must say that reductive materialism undercuts any independent causal power for language, for the expression of the view is not itself causally contributing anything (if reductive materialism is true). It would be absurd for a speech act to be making something happen, and for that speech act to be a statement of reductive materialism, but since the speech act is, by my first counter-claim, only appearing to have causal power, this case does not occur.
The better argument against reductive materialism is that reductive materialists haven't read enough Kant. That is, they're still running around looking for something really real underlying all our impressions, psychological states, etc, etc. But this is just futile. You're never going to find the really real, in part for the reasons that Bryan is alluding to, such as that we pretty confident language has some effect on our behaviour, and in part because the search only leads us to more things that appear to us in a certain way. There is a genuine absurdity: in looking for the really real, you only ever find something that appears to be really real. The really real is nothing but a chimera. Once that idea is disposed of, it then becomes very possible to claim that, for example, social influences have genuine causal effects and not have to tell any story more complicated than "well, if they do, then all the shit people do makes a lot more sense".
The obsession with the really real is widespread in philosophy, and probably in normal life as well. (For example, here is an otherwise interesting attempt to refute moral relativism which makes the same error of looking for a really real good.) Daniel Dennett, for example, although well-known for his view that psychological states are real because they are explanatorily useful, also frequently makes claims that suggest that psychological states are not (say it with me) really real. I'm always shocked when he does so, though, because a modest criterion of the real -- like, say, explanatory utility -- would seem to gel better with his overall view. But, on the other hand, it is always tempting to see science as getting us to something really real. What's important to note, though, is that scientists only ever see, hear, smell, taste, and touch in exactly the same ways everybody else does. They are just as constrained by the way things appear to them as anyone. There is no such thing as privileged access to the really real.