I often use a theory’s inability to solve the problem of other minds as evidence that a theory is lacking something important. For example see here or here. Generally my argument goes as follows: we only have access to physical facts about other people, and since the theory in question argues that the mind depends on things other than the physical we can’t deduce from the physical facts that the other person has a mind. Thus the problem of other minds can’t be solved by the theory. One way such a theory might attempt to defend itself would be to argue that we have access to a non-physical awareness of other minds, but since it is obvious, by experiment, that we can’t detect the presence of other people in the absence of physical information I dismiss this possibility.
A much more interesting defense goes as follows: we have access to non-physical information telling us when another person has a mind, and that this information “piggybacks” on the physical information (which explains why we can’t sense the presence of other people in the absence of physical information). A bad way to respond to this is to say that it violates information theory, since information theory contains some implicit assumptions of materialism, which those who defend an immaterial theory of the mind may reject. We might then create the following defense: we can’t tell if a person has a mind from seeing a small square of their skin, and shouldn’t this be enough to give us access to the non-physical information? This response is also insufficient because the person we are debating with could always respond with the assertion that this small patch doesn’t give us enough of the non-physical information to make a judgment.
A valid response to this idea is to consider other situations where we feel that we can deduce the presence of other minds, for example by observing actors in a film we deduce that the actors have minds. However there is no direct connection between the actors and us to carry the non-physical information, and thus the idea of non-physical information riding on physical information cannot explain how we are able to know that other people have minds. Of course our mental immaterialist might argue that somehow the non-physical information has found its way onto the film as it was being shot, and then was somehow copied by the physical process of making copies of the film for distribution, and was then released from the copy onto the screen, but honestly this assumption is so convoluted and unwarranted (and slightly ridiculous), that we can reject it simply with Occam’s razor.
Anyways I just thought I should mention this reasoning, since I am sure that I will use the problem of other minds in future arguments as well, and I would rather simply link to this comment when someone eventually brings up the objection I have raised here. If you want to read some philosophy that makes actual headway I encourage you to read the other post I made today, it was much more interesting.