Quite some time ago I received the following question: “Does psychological reductionism prove materialism?”.

The question is very confusing and, in my opinion, shows multiple misunderstandings on how certain premises lead to certain conclusions.

Lets start by defining some terms. Materialism is defined as the claim that “only matter exists” (which I define as “absolute materialism”), reducing the discussion to the dualist/monist debate on mind/brain theory is ludicrous.
Physiological reductionism tries to show how all human aspects, like consciousness, memory, the self, qualia, abstract reasoning and the intellectual grasping of universals etc are all reducible to physical brain processes. Such position is called by many “mind body monism”. Refuting such position is beyond the scope of the article, but for the people interested in the issue, I advise reading these three books by J.P. Moreland: “The Soul” by J.P. Moreland (which is easy and accessible), “Consciousness and the Existence of God: a Theistic Argument” and “The Recalcitrant Imago Dei, Human Persons and the Failure of Naturalism”; these two books by R. Swinburne: “Free Will and Modern Science” and “Mind, Brain, and Free Will” and “The Soul’s Upward Yearning, Clues to Our Transcendent Nature from Experience and Reason” by Robert J. Spitzer.

Going back to my original point, even if mind body monism were true, it would be practically irrelevant to the defense of the materialist position. Claiming that “only matter exists” cannot be defended by showing that matter has explanatory power for a specific and single phenomena f. And even if matter could be a complete explicans (“what explaines somtheing”) of every explanandum (“what has to be explained”) , that still that wouldn’t defend adequately the materialistic position! In fact, non material entities could still exist and simply have no interaction whatsoever towards the material world. One example would be the reasonable position that mathematical entities are abstract objects which have no casual power in the material world.
This is not to say that the quest regarding brain states and the nature of thought is not important. I would rather say, it is extremely important! Especially in proving the existence of God through the “argument from consciousness”. The reason why I the question concerned me is that is shows how now days that the idea of “proof” or “data” is strongly misunderstood. We ought to realize what it takes for a position to be proven right or wrong. The consequences of not seeing this are the sad ideas some people have like the view that a refutation of arguments for God’s existence, in some mysterious way, shows that God doesn’t exist.

Having said this, I take this particular question as an occasion to write what are the real arguments for materialism so that Christians may be aware of what he will likely encounter in a discussion with a non believer. Obviously, at the due time, each of these materialist claims will be addressed in our future articles.

The “best” way to argue that “matter is all that exists” is trying to argue against what could account for non material entities (i.e. God). The connection between materialism and atheism is very strong, and such correlation is not accidental. The non existence of God would in fact create a problem in trying to account for non material explanandums, hence undermining their existence. Therefore materialism can be defended by undermining the existence of non material entities by arguing for the “non-existence of God”. This, in my opinion, is the reason why virtually every atheist considers himself even a materialist.

The non existence of God can be argued through the following (weak and blatantly false) arguments:

-the probabilistic problem of evil (for the subject I advise reading Plantinga’s book “God, Freedom, and Evil”, and “God and The Problem of Evil: Five Views)
-the probabilistic problem of God’s hiddenness
-the probabilistic problem of God’s irrelevance (in which is argued that because God does not play any role as an explicans in the world He probably does not exists. Argument defended by Alex Rosenberg in the debate “Is Faith in God reasonable” with William Lane Craig).
-probabilistic Occam’s razor approach (in which it is argued that more complex explanations are more improbable. God is a more complex explicans than nature itself, hence God most probably does not exist).
-the probabilistic problem of expected universe (in which it is argued that if God exists the universe would be more anthropically oriented. For example the universe wouldn’t be so big). On this issue I advise reading Swinburne’s book “The Existence of God” in which he studies the concept of “expectancy”, that is, what we would expect if God existed, by using a Bayesian approach to the question of God existence.
-God as conceptually inconsistent (in which it is argued that a pure actuality cannot exists given the supposed paradoxes it would entail. A famous paradox is the omnipotence paradox). See the book “The Coherence of Theism” by R. Swinburne for a laudable refutation of this argument.
-the argument from traceable causes (in which it is said that the effect resembles the cause. This implies that because the explanandum is not perfect (in this context, the material world) the explicans cannot be perfect, hence it cannot be God.
-Dawkins’s Ultimate Boeing 747 argument (this argument is so bad I will ignore describing it).

Christians should be even aware that, on the other hand, materialism could be defended in a weaker version. I will call the weak version of materialism “practical materialism”, which holds that, even if non material entities can and may well exists, they have nothing to do with our world and are therefore irrelevant to us (practical materialism implies that all explicans are material). I hold that psychological reductionism wasn’t even able to come close defending “practical materialism”. As I have already written, just showing that the supposed non material human aspect can be reduced to material entities does not show neither that “all that exists is matter” (absolute materialism) and neither that “all explicans of this world are material” (practical materialism). In fact, given that all presented materialistic arguments in favor of mind body monism are true, it could well be that there are phenomenon in the world besides mind-body interaction that need non material explicans.
To my knowledge, practical materialism can be argued through a few (weak and blatantly false) arguments:

-the rex cogitans/rex extentia Cartesian problem extended to all physical non physical interaction (therefore not only limited to the mind/body interaction). In this way, a case could be made by saying that non material entities cannon influence material entities given their “structural difference”. Therefore the material world would be self sufficient and self sustaining with all of the explicans within the system material themselves.
-empiricism defended as the only possible form of knowledge. With such a stance it would be worthless to argue whether non material entities exist and therefore we would have to act as if they did not exist.

I hold that if a believer is able to confidently address such objections he will be in a good position to defend the Faith against the widespread naturalistic philosophy of our days.

In Christ,
Amedeo Da Pra