So, I would maintain that there are gaps and there are gaps. It is not just pointing to an unsolved engineering problem in nature. First of all, the categories of the mental and the physical are logically incompatible categories. You start attributing mental properties to physics and you might end up being told that you are no longer describing the physical at all. Purpose, normativity, intentionality, or aboutness, all these things are not supposed to be brought in to the physical descriptions of things, at least at the most basic level of analysis. ¶ Let us consider the gap between the propositional content of thought and the physical description of the brain. My claim is that no matter in how much detail you describe the physical state of the brain (and the environment), the propositional content of thought will invariably be undetermined. … As I see it, it is not a matter of getting a physical description that will work. In my view, the logicoconceptual gap is always going to be there regardless of how extensively you describe the physical. As I said earlier, bridging the chasm is not going to simply be a matter of exploring the territory on one side of the chasm. … [T]he "God of the gaps" or even a "soul of the gaps" response to the argument from reason does not work. I am not saying that we just cannot figure out right now why the mental states involved in rational inference are really physical, I am suggesting on principled grounds that a careful reflection on the nature of mind and matter will invariably reveal that there is a logical gap between them that in principle cannot be bridged without fudging categories.