I need to go back over what the Steve argument is. It is a response to the "anti-causal" reply to the argument from reason, or, more particularly, the problem of mental causation. Actually, it's one of a few arguments I use against this position, which goes back to Anscombe's critique of Lewis. I have to give kudos to Clayton for keeping focused on what this post is about.
The Steve argument is an illustration of the fact that when we say that someone is rational, we are saying that evidential relationships are relevant to the actual occurrence of beliefs as psychological events. In particular, when we try to explain why we are rational in believing something, we make counterfactual claims about the relationship between evidence and our beliefs, such as "If the evidence for evolution weren't so strong, I wouldn't believe in it." A typical way in which people impugn the rationality of others is to say that smart people believe things for not-so-smart reasons, and then use their reasoning powers to justify what they have already committed themselves emotionally to believe. In fact, people like Loftus very often charge that Christians are something like Steve; that is, they for a belief in Christianity through processes that could just as easily produce a false belief as a true belief, and then find whatever arguments they can to undergird those beliefs which were really reached in a non-truth-conducive way.
But what we are saying when we say we believe something for a good reason is that the presence of reasons is relevant to the production of our beliefs, that, unlike those benighted folks over there, we have actually paid attention to the evidence and are following it wherever it leads, whether it makes us feel good or not.
But what that means is that evidential relationships are relevant to what beliefs we hold, and therefore, what states our brains get themselves into. But evidential and logical relationships are abstract states. They are not physical things, and they do not have particular locations in space and time. Yet they are, apparently, causally relevant to the beliefs we form. Or, at least they can be.
But these same people will say that the mind is the brain, and that what goes on in the brain is simply physical causation playing itself out. Abstract objects don't, they say, cause anything to happen in the brain, since the brain is a physical system and events in the brain are caused just like any other events. It's just the laws of physics playing themselves out.
Lewis wrote: But even if grounds do exist, what exactly have they got to do with the actual occurrence
of the belief as a psychological event? If it is an event it must be caused. It must in fact be simply one link in a causal chain which stretches back to the beginning and forward to the end of time. How could such a trifle as lack of logical grounds prevent the belief’s occurrence or how could the existence of grounds promote it? (1960b: 20)
(1960b) Miracles: A Preliminary Study, 2nd edn. (London: Fontana, 1974)
It seems to me that this points to something paradoxical in the naturalist's view of reasoning.