Massimo Pigliucci has a great post at Rationally Speaking, based on a Twitter survey by Oxford University Press, where he first talks about his favorite philosophers of all time, then, to narrow down response on an iPhone app, the most overrated philosophers of the 20th century.
I expanded my thoughts a bit in a comment there, to list underrated as well as overrated, and all-time as well as 20th-century.
Here it is.
Hume is a definite No. 1 on my favorites list. (He was for Massimo, too). He is eminently readable, a bonus among
philosophers. Also, with his thoughts on the self, etc., arguably the
father of modern psychology, and a more distant ancestor of modern
cognitive science. Indeed, we could put Hume in a Tardis or whatever, bring him forward 250 years, and he'd have insights galore to offer in those fields and more. Unfortunately, he was also a racist, which is making me rethink this ranking of him as a favorite, whether overrated, underrated, or rated correctly.
Diogenes. Life would be more authentic if we, and the world in general, thought more like him. Let alone if we acted more like him. Arguably, he's a forerunner and progenitor to some modern absurdists like ...
Albert Camus, the leading expositor of absurdism (do not call him an existentialist) would be No. 3, I think.
Marcus Aurelius might be fourth; I'm not sure. He contributed nothing new to Stoicism, and kind of undercut his own intellectual high ground by naming his son Commodus as heir rather than adopting somebody else, but the "Meditations" are still a pleasure to read.
Ludwig Wittgenstein would be fifth, I think. Here, I strongly part company with Massimo, who puts him on his overrated list. I think the early Wittgenstein of the Tractatus may be overrated ... an affectation for some. The later Wittgenstein? Also an affectation of alleged intellect for many, but that doesn't detract from the fact that his ordinary language philosophy has been influential. And, on the popularity side, anybody willing to brain Karl Popper with a fireplace poker can't be all bad, right?
If I add one more, it's going to be a mythical character, but that's that. Lao Tzu, the alleged founder of Daoism.
Now, a couple of underrated philosophers (all time, not just 20th C):
1. Pyrrho. Pyrrhonic Skepticism influenced Hume, among others.
2. Camus, per a comment above. More insightful than Sartre, yet barely even gets considered as a philosopher by many. And he should be. Because he was.
3. Gilbert Ryle. Influential on a number of late 20th-century philosophers, including, but far from limited to, Dan Dennett. His "ghost in the machine" is a good modern philosophical restatement of rejecting ontological dualism.
4. Diogenes. Even educated people know little about him other than his comment to Alexander the Great, and they know even less about capital-C Cynicism as a philosophy. It's a shame. I won't load the page up with links, but go to Wikipedia or the Stanford Encyclopedia of Philosophy, and look up both the man and the philosophy. He's underrated precisely because he was a willing contrarian and outcast, and he made that the basis of his philosophy. And, winners write history.
Next, here's my all time, not just 20th century, overrated philosophers.
1. Socrates (my moniker for this blog and more riffs on the myth, not the reality, of the man, and ..
two go together. Plato totally set up straw men for Socrates to argue
against, in the Sophists and others. The reality is that the Sophists were wanting to make the roots of a classical, Hellenic "gentleman's" education available to those who didn't have the time and money of the upper crust for private study. And, one need not be Izzy Stone to see that both were
antidemocratic elitists, to boot, given that Socrates failed to condemn either the first or second revolt Alciabiades led/instigated against the Athenian democracy.
More thoughts of mine on Socrates here.
3. Aristotle. Were he Jewish and
200 years older, we'd probably finger him as the author of the "P"
strand of the Torah. Highly influential in terms of basic logic, yes,
but, if we want to in a sense call him the first philosopher of science,
he was a disaster. And, there were early scientists and technologists around. His contemporary Eratosthenes used trigonometry plus geography to produce a highly accurate measure of the earth's circumference. A century later, Archimedes was a technological and inventive wunderkind. Therefore, Aristotle had no need to make the massive amount of evidence-free statements about human and animal life, classifications of life, etc. that he did. Nor, per thinking on metaphysics and other fields of philosophy at the time, did he have to postulate the four causes that he did. And, on ethics? Massimo is a virtue ethicist and so he loves Aristotle. I don't, as an educated layperson, consider myself to be aligned with any one school of ethics. I do claim, and did in comments to Massimo's 2012 blog posts about schools of ethics, that virtue ethics has about as many problems as Kantianism or utilitarianism.
4. Kierkegaard, Dostoyevsky and other Christian existentialists. Basically, they failed in their attempts to give Christianity, especially theodicy, an intellectual veneer in the late 19th century and beyond. That's especially true when they're mashed up with process theology (see below).
5. Dan Dennett. No, this is not a Poe or a total joke. He's not written anything original in nearly 20 years, and has actually made some whoppers, from where I sit, beginning with the evidence-free flat statement that evolution is algorithmic. He also gets merit here because of his philosophical influence on modern Gnu Atheism in general.
Contra Massimo, I don't think Wittgenstein was overrated. He is a mixed bag, but I'd put him as ... about correctly rated, overall.
OK, underrated 20th century philosophers. This list is much shorter because, as noted above, I'm not a professional philosopher and therefore don't have the level of insight, or personal attachment, that Massimo does.
Overrated, 20th C:
1. Heidegger/Derrida/Foucault and any progeny of any of their schools of thought. Let me add Stanley Fish by name. Basically, deconstructionism is self-refuting, petard hoisting, etc. Derrida doesn't have a leg to stand on. Structuralism has enough similarities that my critique extends to Foucault. Heidegger? His existentialist contributions to what became process theology are more than enough reason to put him here (adding Alfred North Whitehead, Teilhard de Chardin, Paul Tillich, and any other expositors of the Ground of Being), setting aside his Nazi friendliness.
2. Dennett as a special case. He certainly influenced me, nearly 20 years ago, but, I've moved on. Beyond his "recycling" and his refusal to accept that rejecting a "Cartesian meaner" logically also means rejecting a "Cartesian free willer," his invention of the word "Brights" for secularists was bad enough, but his following claim that there was no connotation, no implication, about religious people ... I see that as a transparent lie.
3. Sam Harris and any other Gnu Atheist claiming to have disproven the existence of god. Harris, especially, knows what any open-minded person who has taken a basic class on logic, formal or informal, should know -- attempting to prove the nonexistence of anything is the logical equivalent of dividing by zero. Vic Stenger is another Gnu who does this. Harris deserves additional mention for claiming Buddhism is just a psychology.
4. Jean-Paul Sartre, with apologies to my Facebook friend Brett Welch. I think Sartre's stubborn refusal to accept the truth about Stalin and Stalinism, contra Camus, speaks a lot for and about him as a thinker. And, speaking of that, I think Camus had the edge on him as a writer, overall, at least a philosophical writer (No Exit is psychology first, philosophy second, as are several other works by Sartre) and think Sartre was jealous.)