The uncomfortable thing about the drums being used to explain the Master's insanity is that Simm is arguably the sanest Master (and arguably the least Doctor-sexual). His reasoning was coldly rational and was based on him successfully exploiting existing systems. So "he's doing this because he's insane" is just very ableist. Now, Ainley? Ainley's bonkers.
A lot of people, quite wrongly, think “sane people think killing people is wrong, therefore, any murderer is insane”. This is ableist as well as bullshit, sane people kill each other. The very fact that insanity is a plea in murder cases shows that it’s assumed most murderers are sane.
Now, the Master? If we don’t assume anyone who commits a murder is insane, what evidence do we have that they are? Mostly what we have to go off is “how rationally do they behave” (which is most of my basis for mentally ill Doctor headcanons) and “do the characters who describe them as insane have any basis for it?” I’m not even going to ask for any background in mental health care, although I do headcanon that as being one of the many things the Doctor has studied.
Usually, when someone is calling the Master insane it’s either based off of “I hurt people for fun, so I’m probably a sadist”, or “I don’t see other people’s lives as important”. Look, I can’t diagnose the Master and I’m going to stop trying. Do I think he’s mentally ill? In any of his incarnations? I don’t get that off him as much of I get it off the Doctor, because the Master seems to know what he’s doing and be in control of it. It’s just more destructive.
I frankly would believe that the sixth master is claiming mental illness so he doesn’t have to consider why he’s actually doing things.














