A friend who has over time tended toward criticism, wrote me recently stating that, “... you can't study one philosophical idea without studying all of philosophy, as Arthur C. Danto pointed out.” I realized right away, of course, that this was some sort of fallacy based on appeal to authority, but also having to do with the words, 'one' and 'all'. Since what poor Danto actually wrote, tearing into Wittgenstein, was, “To do philosophy at all means doing all of philosophy at the same time. That means that philosophers cannot be specialists.” (Letter to Posterity) Though this seems a little fallacious in itself, however, it’s much better than the second-hand version.
Now let’s look at the fallacies. Contextomy is the tearing of a quotation to suit a specific purpose. However, here it is based on an appeal to authority, not only based on citing, “all of philosophy”. But here the appeal to authority is strengthened and extended by the imperative, “you can’t study…”
There’s an important difference in intentions between a student and a philosopher trying to create new definitions, such as was poor Wittgenstein. Let’s even look further by focusing on Danto’s phrase. It seems he has created a false dilemma, the idea that one must be active in all areas, or only one, the fallacy of the excluded middle. It creates a false choice between doing everything, or doing less than that, and being wrong and culpable. So many of our great philosophers, especially the Ancient Greeks indulged in only one or two areas, Plato in ideals and debate, Aristotle in science and language, Kant in sufficient reason and then in absolute morality. Yes, there are great philosophers with products in more than one area, but these philosophers chose freely, after treating one discreet topic acting as, “specialists”, to choose another one.