Final answer:
The argument is invalid because it commits the fallacy of the undistributed middle.
Step-by-step explanation:
The problem with the argument is that it is invalid. The argument commits the fallacy of the undistributed middle. The first premise states that the mind has the property of being able to exist separately from the body, but it does not establish this property as unique to the mind. The second premise states that the body does not have this property, but it does not consider the possibility that other things may have this property. Therefore, the conclusion that the mind is not the body cannot be logically derived from these premises.