Given the scope of Searle's book, and its stated aim of setting straight the basic problem at the root of modern philosophy of mind, one would naturally expect to find some discussion of free will, and of how Searle's theory relates to the understanding of this issue. It is very remarkable, therefore, that there is no discussion whatever of free will in Searle's book; the subject is simply never mentioned, except in one brief remark [29].
In a previous book [30], Searle has stated that he regards the issue of free will as a basic mystery, which he is unable to solve and which, further, is likely to never be solved. I think it is fair to assume that Searle still holds this view of the issue, and that is why he was not inclined to discuss it.
When reading Minds, Brains and Science, several years ago, I was very puzzled by Searle's statements on the subject of free will. Searle regards consciousness as an irreducible phenomenon which is caused by underlying material processes, which is unique to a certain class of entities, and which is fully a part of the natural world; most modern philosophers of mind greatly resist admitting that such a phenomenon can exist, but Searle has, quite clearly and forcefully, accepted it. Shouldn't it, then, be easy for him to make the next step, and admit that there's another irreducible phenomenon --- namely, free will --- which is caused by some of the same underlying material processes, which is unique to a subset of the same class of entities, and which is also fully a part of the natural world? After reading The Rediscovery of the Mind, I believe I finally understand why Searle is unable to accept free will.
In David Kelley's discussion [31], free will is a natural extension of consciousness, both in its evolutionary function and in its epistemological status. Kelley sees free will as having evolved for a function which is an extension of the function of consciousness --- a means of discriminating the amount of information available to man, and controlling choices among the range of actions open to man, both of which are far larger than can be handled by the consciousness of any other animal. Epistemically, Kelley sees free will, like consciousness, as an evident fact, caused by underlying material processes and irreducible to them; having accepted the existence of consciousness, having accepted that there exists such an irreducible phenomenon, it is natural to accept that there can also exist another such phenomenon, namely free will.
The key point here is that Objectivists see ontology and causation as essentially the same; so every phenomenon that exists in reality necessarily has effects on the relevant entity's (in the case of consciousness, the animal's) actions. Searle, on the other hand, separates ontology and causation. He then thinks of consciousness, basically, as relating only to the realm of ontology; it is a real phenomenon, but it does not cause anything, or, at least, it is possible in principle that it does not cause anything. And this, apparently, is the only kind of irreducible phenomenon which Searle is willing to defend.
Free will, in contrast, clearly relates to the realm of causation; there's just no way to make any sense of a notion of free will that has no effects on man's actions. And in the realm of causation, Searle continues to hold the same dualistic assumption which he attacked so forcefully in the realm of ontology. He can't accept that there could be an irreducible phenomenon which is caused by neurophysiological processes in the brain, is itself a feature of the brain, and has effects on the animal's actions.