What is the difference between sanity and insanity?
As someone diagnosed schizoaffective (though fortunately fully stabilized on meds) I think "insanity" is easy to spot from the outside. We know it when we see it in someone else but the insane person is, in my experience, usually incapable of spotting it in themselves. All my delusional experiences have been almost like dreaming while I'm awake. I can see now that my thinking was terribly distorted but while in a state of insanity I couldn't tell that. Here I'm talking about real insanity, not the casual way people sometimes use the word, like "anyone who goes sky diving is insane."
Real insanity is, for me, very strange and difficult to pinpoint with a definition. For instance I could say that insanity is a form of erroneous thinking but there are other forms of erroneous thinking other than insanity. So I couldn't say that erroneous thinking is "THE" difference between sanity and insanity. Because there are forms of sane thinking which are erroneous too.
Understanding insanity is something humans may or may not ever be able to do. Why does it happen? You could say it happens because chemical X starts to come out of region Y in the brain but that's not really what we humans tend to mean when we ask "why" something happens. Most of the time I think we are looking for an answer along the lines of: "because it helps us to be better able to survive under conditions XYZ" or "the Devil is trying to possess us" or some sort of profound insight into the ultimate nature of the world. But perhaps all we will ever be able to successfully conclude is something like chemical X starts to come out of region Y in the brain.
But who knows? Maybe the next Albert Einstein will come up with a profound understanding of reality which will explain insanity.
I can somewhat agree with Chomsky on the topic of Derrida and post-modernism. I spent two semesters studying various "continental" thinkers such as Heidegger, Husserl, Derrida, Foucault et. al. Derrida and the whole deconstruction movement are utterly incomprehensible to me. Really sounds like a lot of nonsense on the face of it. Foucault I found a little interesting. Some of his language is pretty whacky but overall he explored some interesting themes like trying to link the history of the sanitarium to that of the leprosarium. He was obsessed with power and how it is exerted by one over another. But yeah, most of his writing he seems to go out of his way to sound incomprehensible where plain language might work better. Most of what I learned of Foucault came from secondary sources as a result. I spent a few years after college studying Foucault but didn't get a whole lot out of it I don't think. Husserl is actually pretty neat and relatively understandable IIRC. He laid the foundation for what has been called Phenomenology. Heidegger is incomprehensible but I've read secondary sources on him that make some sense of his project. Heidegger seems to be the impetus for Derrida from what I understand and part of Heidegger's claim was that he wanted to use language in a way that would release him from certain metaphysical presuppositions. I remember reading his "letter on Humanism" in which he claimed that the word "humanism" is ultimately derived from an ancient Greek prejudice against non-Greeks. He seemed to believe that humanism is therefore somehow tied to racism. Maybe a bit of the genetic fallacy in there, I don't know.
In a sense there is a major divide between continental philosophy and analytic philosophy in the way the philosophers project to their audience. I found that the continental thinkers enticed me to try to figure out what they meant by something where analytic philosophy is much more concerned with making things explicit to everyone. In some senses continental philosophy reminds me a lot of religion and the attempt to decipher things like the Upanishads or a Zen koan. Such things are not self evident and not easily transmitted from one person to another. Analytic philosophy is much more like science and making things transparent as much as possible. It's an interesting divergence between the two schools of thought or whatever you want to call them. I mean I don't understand a lot of the Upanishads or Zen Buddhism but I don't therefore call it nonsense. I think continental philosophy is somewhat similar in some respects. You have the wise sage trying to teach the apprentice something he doesn't quite understand, at least not yet.