The 25th Amendment was intended to be a tool that could be used when the President is "unable to discharge" the powers of his office. The purpose is in the text.

The next question is obviously what does "unable to discharge the powers and duties" mean? I think there are four possibilities. Feel free to add more if you can think of them and we can discuss them.

First, there is the physical incapacitation case. The President is in a coma but still alive. This is an easy case, and I think we both agree that the 25th amendment applies.

Second, there is the obvious mental disorder case. The President is throwing his own feces on the White House lawn. Again, I think that we both agree that the 25th Amendment applies. But now it gets tougher.

Third, there is the "we need to take the keys from Grandpa" case. The President is just like your 90 year old grandpa who should not be driving and everyone close to him knows it because he is a danger to himself and others, but he refuses to turn over his keys. Does the 25th Amendment apply here? Your answer seems to be no. That it can never apply here. I don't see how this is supported by the text, structure, or history of the amendment. My answer is yes, if the required people decide that the President is "unable to discharge". Is a doctor required? That could bolster the case, but the Constitution does not require it. It is whatever the VP and cabinet members require.

Fourth, there is the pure policy disagreement case. Example: The President is turning over the nuclear codes to Russia in 45 minutes and has ordered the military to stand down even though the Chinese divisions are on the border because he was actually a Manchurian candidate. Can the 25th amendment apply here?

To you, it does not because there is no medical problem. But if you adopt this view, there is no constitutional fix. There is not enough time to wait for formal impeachment. The military disobeying this order would probably be unconstitutional because the President is commander in chief.

To me, the 25th Amendment does apply because the only textual standard is "unable to discharge the powers and duties" of his office. The above example fits, and provides a constitutional remedy.

What are your thoughts? Can the 25th Amendment only apply to situation 1 and 2?