Mind, Meaning, and Materialism
Remove mind and meaning goes with it. However, meaning cannot be escaped: our lives are suffused with meaning, from perceptual experiences to the exchange of language. One must understanding that mind just is the realm of meaning, as Mortimer Adler explains. (As others have put it, intentionality is the mark of the mental). This sets up for a fairly straightforward demonstration against materialism, which has been issued by thinkers ranging from Richard Taylor to James Ross.
To modify the usual illustration, imagine you encounter a formation of stones which spells out the sentence, “Welcome to Portland, Oregon.”
However, imagine you discover that this arrangement of stones was formed through impersonal forces. While improbable, let us suppose this is not only possible, but actual. What happens? Well, just that you can no longer believe that the collection of stones is meant to convey any message (that is, any determinate semantic content). The moment you remove an intentional agent behind the stone formation is the moment you remove potential meaning, as well. With one automatically goes the other.
As Ed Feser argues, this has nothing to do about probabilities — it is not a design argument focusing on the likelihood of stones being formed in any complex arrangement by impersonal forces. Rather, the point is a demonstrable one: even if stones formed that way, there is no rational basis for thinking they convey whatever meaning we think they do.
Now just replace stones with whatever physical conditions or processes one likes. And replace the meaning of the sentence with whatever other meaning one likes from human experience (including perceptual). If we hold that all impressions of meaning are the result of impersonal forces, then we lose all basis for thinking anything really means anything, including the meaning of our own thoughts — including the meaning of THAT thought.
For these reasons, materialism is not only incapable of making sense of meaning (and rationality) but self-defeating.