By Elias Ayala (MDiv & M.A.T.)
The idea that human beings are merely physical entities with no spiritual or immaterial component is known as physicalism. Interestingly enough, there are some professed Christians who hold to this idea, but I think the biblical teaching clearly expresses the reality that man is both a body/soul composite.
I think the difficulties with this position is legion, however, I will focus upon one important difficulty that renders physicalism irrational. This is the issue of “personal identity through time”. If human beings are reduced to purely physical entities, then we run into the problem of constant change and flux as fundamental to our being. That is to say, that physical things within the material universe undergo constant change throughout time. Our physical bodies are no different, and hence our physical bodies are constantly undergoing change. However, if there is nothing about man that is enduring, then what is man if not a constant bundle of changing particles. Remember, on physicalism, there is no immaterial soul unaffected by physical change that grounds our unchanging personal identity throughout time. On physicalism, there is no enduring “self”. Personal identity is rendered meaningless, and hence, I am not the same person as I was prior to writing this article.
Getting back to whether such a notion is rational. Let us ask the question: Is it rational to believe in a position that does not itself provide a grounding for our own personal identity throughout time? If I have no personal identity then who is affirming or denying the position? Indeed, for the person who holds to such a position, it would seem irrational to argue about it since to argue with another person seems to presuppose the personal identities of both persons involved in the argumentation.
Think about it. The persons arguing would not be the same persons by the end of their conversation. The person who began the conversation no longer exists since the elements which made that person who they were are different since the physical body continually undergoes change. A fascinating point to keep in mind for the person who holds to this position is that while it is true that they hold to such a position, they cannot act and/or speak as though its true.
I remember a very interesting conversation I had with a physicalist. He admitted that the physical body continually undergoes change and that there is in fact no enduring self throughout time; yet on the other hand, the person continually referred to himself with terms that implied personal identity. At one point, he admitted that since there is no personal identity throughout time he doesn’t exist.
I do not think that this is a rational position to hold. Rather, the view which posits an enduring self throughout time is much more rational even though I have not in this article fleshed out specific arguments in its favor; something that has been done quite convincingly within the philosophical literature.