Philosopher Ed Feser argues that this view is simply false and he adduces something called intentionality as just one of several phenomena that cannot be explained as a function of matter or neurological processes:
One aspect of the mind that philosophers have traditionally considered particularly difficult to account for in materialist terms is intentionality, which is that feature of a mental state in virtue of which it means, is about, represents, points to, or is directed at something, usually something beyond itself.The debate has fascinating implications. If there's more to us than just the chemicals that make us up, if there's something immaterial that's an essential element of our being, then is that immaterial mind (or soul) something that's not subject to death as physical matter is? Might there be something about us that continues to exist even after the body dies?
Your thought about your car, for example, is about your car – it means or represents your car, and thus “points to” or is “directed at” your car. In this way it is like the word “car,” which is about, or represents, cars in general. Notice, though, that considered merely as a set of ink marks or (if spoken) sound waves, “car” doesn’t represent or mean anything at all; it is, by itself anyway, nothing but a meaningless pattern of ink marks or sound waves, and acquires whatever meaning it has from language users like us, who, with our capacity for thought, are able to impart meaning to physical shapes, sounds, and the like.
Now the puzzle intentionality poses for materialism can be summarized this way: Brain processes, like ink marks, sound waves, the motion of water molecules, electrical current, and any other physical phenomenon you can think of, seem clearly devoid of any inherent meaning. By themselves they are simply meaningless patterns of electrochemical activity. Yet our thoughts do have inherent meaning – that’s how they are able to impart it to otherwise meaningless ink marks, sound waves, etc.
In that case, though, it seems that our thoughts cannot possibly be identified with any physical processes in the brain. In short: Thoughts and the like possess inherent meaning or intentionality; brain processes, like ink marks, sound waves, and the like, are utterly devoid of any inherent meaning or intentionality; so thoughts and the like cannot possibly be identified with brain processes.
Materialists scoff at the idea, but materialism no longer commands the allegiance of philosophers like it did in the 19th and 20th centuries. There's too much it can't explain and intentionality is just one example.