And this is precisely why philosophy (insofar as it has a content) as an academic subject should not pervade other subjects, but rather should remain firmly fixed in the philosophy department.
I hope that "pervade" was a poor choice of words. " to become diffused throughout every part of" If philosophy did not "pervade" other subjects, not only would students of other subjects such as history, literature and psychology be unable to really understand their subject, but the vital influence of philosophy upon other subjects would be lost - and I am not sure that many subjects could survive the removal of philosophy.
I disagree. I think logical positivism and certain other philosophical movements are -wrong.-
That's fine. Really, I do not see how your disagreement with certain philosophical movements means that we disagree. I am simply saying that philosophy evolves over time in the same way that the other subjects evolve. Philosophy and other subjects are often changed by the same events: consider the influence of the atomic era on philosophy and literature, for example.
I think that human nature is a constant.
And that may be so. But the human condition is in constant flux and subjects, including philosophy, address not only human nature but also the human condition.
I don't think that Scholasticism is outdated. I think that, insofar as Scholasticism has a philosophical content, that content continues to be as true now as it ever was.
I am not trying to contest the truth or falsehood of Scholasticism or any other philosophical tradition. No philosophy is perfectly true: describing human nature/condition is one step from the truth of human nature which is the experience of it.
To be a Scholastic is not to be "wrong" necessarily; my own philosophy contains a plethora of anachronisms. Scholasticism's relevance in other subjects is naturally less than more modern philosophies because Scholasticism is so old. When something is new it excites innovation; as it ages, the room for innovation decreases and eventually newer ideas take prominence as they offer greater room for innovation.