I've been watching some video lectures online, and in some of the videos, the professor argues essentially as follows:

Both the dualist and the physicalist believe in the body. This is status quo. The dualist then expresses a belief in the existence of the soul. Therefore, we can consider the position of the dualist as the claim "there exists a soul", a claim made in a world where we take the existence of the body as given. Therefore, as the dualists are the ones making a claim, they are the ones with the burden of proof.

Is this logically sound?

The reason I don't believe it to be so is that by looking at things from a different perspective, you can easily put the burden of proof on the physicalists:

Both the dualist and the physicalist believe that there exists a body. This is status quo. The physicalist then expresses the belief that no other substance exists. Therefore, we can consider the position of the physicalist as the claim "there exists nothing else but the body". Therefore, the physicalists are now making a claim here, and thus hold the burden of proof.

That is just one perspective. One could keep changing things, such that the burden of proof lies on both parties.

My question is essentially whether I am wrong, or whether the sentiment expressed by the professor really was logically incorrect.

  • 2
    Hi, welcome to Philosophy SE. We generally ask users to provide the source of their quotes. "He who makes the claim holds the burden": in your scenario they both make claims, so they both hold the burden. The status-quo is the neutral position of reserving judgement. Neither side met their burden so far, but they both have their arguments.
    – Conifold
    Dec 21 '16 at 0:14

The assumption 'and nothing else...' is a sort of 'ceteris paribus clause', the kind of requirement that is usually implicitly assumed -- that all the things not explicitly mentioned by any option affect all options equally. But if you uncover it and inject it explicitly, you should do so uniformly. The dualist is implicitly saying "There is a body, and a mind, and nothing else." So he still has one more assertion at stake.

After all, why not have five coequal substances all separately constituting everything? Well, we just don't like that. It is true that every claim is a claim, but claims that introduce more objects are more of a burden than claims that avoid doing so, due to "Occam's Razor".

At the same time, you have omitted the idealists. It seems silly to pit the awkward compromise against one of the two contenders that it lies between, rather than both of them. To my mind, it takes the whole question of dualism out of context.

It is easier to insist there is a mind than to insist there is a body, because of the directness of experience. I might be imagining my body, but to imagine my mind suggests a mind already, at least naively. So the claim here that really 'has the lowest-lying center of gravity' in terms of dubitability has been left off the table.


Typically in philosophy, the person making the claim has the burden of proof. It doesn't matter if that claim is a positive or negative claim. However, in some disciplines it works differently. For example, in science, the burden of proof defaults to the one claiming the existence of something. This is because the falsification process that science uses is much better suited for falsifying negative claims. If you claim nothing exists, it's easy to provide counter examples by demonstrating something happens. For a positive claim, however, you would have to falsify it by proving that something does not exist, which is much harder to do (maybe you just didn't look in the right place / maybe it only exists on Mars / etc)

This is, of course, why science typically does not posit the existence of the soul. The mere lack of an experiment showing a soul exists would not be sufficient to falsify the claim that one exists.

  • Agreed. When it comes to science refuting dualism, all we can ever really say is 'we have no evidence of non-material substance, and no known way of acquiring it, and that is our evidence of it's non-existence'. For dualists, we're starting from the vantage point of zero evidence, so if they want to make a claim, they can only validate their claim by finding that evidence. Dec 21 '16 at 22:08

Get a new prof. Your intuition is correct. We agree that the body exists. It does not follow that we agree about anything else. In particular, it does not follow that there is no soul.

So the physicalist is under the same burden of proof to show there is no soul as his opponent is to show there is a soul.


One can always find "complicated" answers to everything. However, your teacher's answer is logically correct if we restrain to a "simplistic (localized)" scenario.
I believe that what your teacher is trying to show, is that since both dualist and physicalists agree on the existence of the body, then no additional proof is required by either side. However, for additional matters in which they are in disagreement, the burden of proof will belong to whichever side wants to make additional claims.
Physicalists are finished with their claims, but since dualists want to add the claim that "there exists a soul," then it is their burden to provide the proof of it.

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