Moral Argument from Responsibility

The idea that the mind is fully explainable in terms of the brain is very common today (called the mind-brain identity thesis). If the mind and brain really are identical, and if every mental event is created by a brain event, then it is very difficult to see how anything like free will could exist, even more modest notions of freedom ( such as compatibilism, which contends that free will exists but that it is not incompatible with determinism). If every mental event is caused by brain events, then we don’t have any sort of free will. Why? We don’t control brain events, so if they cause everything that happens in our mind, then we don’t control what happens in our mind, and hence, our behaviour. In fact, the naturalist is committed to the view that the mind must be fully explainable in terms of some material thing (the best candidate obviously being the brain). However, if we don’t have any sort of free will, then we can’t be responsible for our actions. If we can’t be responsible for our actions, we can’t be morally responsible for our actions. If we can’t be morally responsible for our actions, then we are not moral agents. This clearly contradicts our experience of the world – and our perception of ourselves and others as being responsible for what they do. We regularly assign praise and blame to other people based on how they act. However, if the mind-brain identity thesis is correct, then this is irrational. No human being is an appropriate “target” for moral praise or blame, because they are not responsible for anything they do.

Responsibility and Mental Causation

In order for some sort of free will to exist, mental causation must be the case. That is, our mind must be able to effect changes in our brain, rather than only the other way around.  Why? We cannot be free unless our decisions are not prewired and out of our control. We must be able to make a decision based on our own thoughts in a way that is not predetermined by our brain. However, it seems unlikely that mental causation could be the case if materialism or naturalism is true. Mental causation implies that the mind can act independently of the brain. The mental event that caused an effect on the brain in mental causation cannot itself be caused by the brain, because then that wouldn’t really be mental causation. The mental event that represents mental causation cannot itself be represented by a brain event, because then the brain has simply caused an effect on itself. And then we are still fully determined by brain events that we don’t control. So the mental event must act independently of the brain in order for mental causation to happen. But if that’s the case, then the mind cannot be fully explained in terms of the brain. This can be conceived as an argument against naturalism:

  1. Naturalism implies that the brain causes everything in the mind.

  2. If everything in the mind is caused by the brain, then we don’t have control over anything in our minds.

  3. If we don’t control anything in our minds, then we are not responsible for anything in our minds, and consequently our behaviour.

  4. If we are not responsible for anything in our behaviour, then we cannot be morally responsible.

  5. We are morally responsible for what we do at least to some extent.

  6. Therefore naturalism is false.

Naturalists and the Mind-Brain Identity Thesis

Some people might have a problem with the claim that naturalism implies the mind-brain identity thesis. Naturalists don’t believe that there exists anything truly non-physical. This means that something physical must fully account for the mind. The brain is obviously the best choice. Naturalists cannot admit that any part of the mind is non-physical, otherwise that would disprove naturalism. Thus, every aspect of the mind must be caused by something physical (the brain). This means that we are fully determined by brain events and consequently cannot be responsible for anything.

As an Argument for God’s Existence

We can also formulate this as an argument for God’s existence.

  1. Responsibility, including moral responsibility, implies mental causation.

  2. Mental causation implies that the mind can act independently of the brain.

  3. If the mind can act independently of the brain, then it is probably not physically explicable or reducible to another substance.

  4. If mind represents a non-reducible reality, then it is best explained by a greater mind that could have created human minds.

  5. Therefore, a greater mind exists.

 We’ve established that human minds are not explainable in terms of the physical and are not reducible to non-mental properties. However, human minds must have an explanation, because human minds could have failed to exist (they are contingent). Also, human minds clearly began to exist, so they require a cause as well. If minds are non-reducible, then mind represents a fundamental feature of reality. If mind is not reducible to non-mental properties, then the most simple way to explain it is to explain it in terms of “more” mind. This mind must be capable of creating all human minds (so it must be very powerful). It must be metaphysically necessary, because otherwise we will have to posit an infinite regress of contingent or impermanent minds (which is absurd). (For more information on why an infinite regress would be absurd, look at the arguments against an actual infinite under the Kalam Cosmological argument). This mind must also be personal, because minds are always personal. It must be immaterial, because physical things cannot be metaphysically necessary. Also, we’ve established that the mind must be able to act independently of the brain, so it is not necessary to think that the being has a body. So, we’re looking at a metaphysically necessary, immaterial, personal mind that created all human minds.