Applying Kant's Moral Proof to Materialism

I will briefly sketch Kant's Moral Proof for the existence of God, and then apply the same kind of reasoning to Materialism.

It is well known that Kant gives a harsh criticism to all theology in the first critique, and shows that (theoretically speaking) God is unknowable.  We cannot have so much as an opinion about God's existence.  We do not know if God is possible or impossible.  

For many, Kant's earlier criticisms of theology produce confusion in light of his later Moral Proof of the existence of God.  While one can say that the Moral Proof is not theoretical, and so has nothing to do with the criticisms he leveled against theology, this doesn't do any work to help us understand the Moral Proof and to remove all lingering suspicion that he hasn't gone back on his previous work.

To understand the Moral Proof, one must first understand a subtlety about ends (goals) that we will (undertake):  when we will an end, we take the means necessary for the end to be possible.  Now, if we will an end that required supernatural means, we take these supernatural means to be possible. 

If will the Highest Good (the union of perfect virtue and perfect happiness) we also have granted the possibility of the means.  The means must be able to have our actions in the world that are motivated by duty impact the way we are rewarded in nature.  The cause that would combine our happiness with our virtue could not in nature, so it requires a supernatural cause.  This supernatural cause is God.

Using the structure of this moral proof we can take another example of a metaphysical position: materialism.  One may interpret materialism as saying that all of our empirical scientific research is bound up with a study of matter at some level.  At this point, materialism is not a metaphysical statement, but simply a statement of the domain of study for science.  To give this position a metaphysical characterization I will add the following: all attitudes must be constrained, ultimately, to the realm of empirical scientific research, and so ultimately get their explanations in an account of matter.

Just as Kant points out concerning theoretical knowledge of God, it cannot be known if our theory of materialism is true (the reasons for this I will leave aside).  It is, in fact, a practical sort of theory.  It is normative for the way we give accounts of things.  The question, "know thyself", must necessarily mean to know something about matter.  Using the same form as the Moral Proof, we can see a potential motivation for determining ourselves in favor of this metaphysical outlook.

If I am interested in have possible efficacy regarding all things, I will want any possible encounterable problem to be in a domain where I am effective.  To state this another way: if I will that I am sufficient to all of my ends, then all of my ends must relate to that which I can manipulate, and all that I can manipulate is matter.  This end permits me to give a practical denial - metaphysically - to the super natural (even to the will, which becomes a conversational convenience).

There may be other ways of interpreting materialism.  This is all ultimately an attempt to characterize how metaphysical positions are motivated.  For me, this goes a long way in helping me to sympathize with positions (such as materialism) that I find difficult to maintain.  (I do not feel a demand to be sufficient to all of my ends, but I can begin to understand what that would be like, and how that would benefit my existence.)

I think that all these metaphysical positions, accordion to their motivation, can be further evaluated so far as we understand what we do when we ask and answer the question "know thyself".  "Know thyself" here is understood as a question concerning the human being generally (a philsophical anthropology, perhaps).  What interpretation of the human being makes the most sense to us is going to determine our metaphysical outlook.

(Aside: If humanism is taken to mean that humans can be sufficient to ourselves through our own 'meaning making', then humanism will ultimately be a materialism.  Of course, there are other ways of speaking about humanism.)