After majoring in philosophy at Swarthmore, Unger completed his Doctorate in Philosophy at Oxford with Strawson and Ayer. His thesis (completed under Ayer's supervision) did not foreshadow his controversial career. In it he defended a form of reliablism, arguing that when certain of your beliefs don't merely happen to be true, but rather are sustained in ways that, over a wide enough range of situations, ensure that you will have correct beliefs, then those beliefs count as knowledge.
Although he soon moved away from this reliablism, his early papers in the late 1960s -- published when Unger was an assistant professor at the University of Wisconsin at Madison -- explored ideas similarly within the bounds of what he terms "respectable" philosophical discourse.
Ultimately, Unger did not just part ways with reliablism -- he found it utterly unreliable. With "A Defense of Skepticism," published by The Philosophical Review in 1971, Unger entered the almost uninhabited outer reaches of epistemology. Here, he laid the groundwork for his claim that it is impossible for humans to truly know anything. He continued to write about skepticism for the next four years, a period which produced his Guggenheim fellowship, his first book ("Ignorance: A Case for Scepticism," in 1975), but few adherents in the world of philosophy. By this time, skeptics had been a rare breed for at least 70 years. This period also brought him to New York University, where he is still teaching.
Unger's reputation -- for bold thinking and iconoclasm -- grew. After five years of protracted skepticism, Unger moved even further from the philosophical mainstream: rather than merely doubting the existence of things, Unger promoted an extreme metaphysical nihilism, maintaining that almost everything thought to exist actually does not. Unger published papers like "There Are No Ordinary Things" and "Why There Are No People," as well as the previously-mentioned, "I Do Not Exist," denying the existence of rocks, chairs, planets, and plants. Perhaps to counterbalance this radicalism, he also published "Toward A Psychology of Common Sense" in 1982, exploring the mechanisms by which people convince themselves that almost all their concrete common nouns denote real things.
Soon thereafter, he examined the flipside of skepticism: rather than nothing existing, what if everything existed? Here Unger offered an extravagantly rich ontology, arguing for infinitely many worlds containing every possibility, including philosophizing fish. He held that any exclusion from the totality of things, including the exclusion of such fish, would be arbitrary.
Unger's 1990 book "Identity, Consciousness and Value" brought him closer to the realm of what he calls "socially acceptable" philosophy. Eight or nine years in the writing, the book returned to a more commonsensical metaphysics and embraced a form of physicalism. Taking the existence of most of physical reality for granted, he argued that what secures our survival as individual persons is the continuous-enough physical realization of our core psychology.
Looking back, Unger reflects that his next turn, a spin through ethics, reflected a desire to do something relevant to how we lead our lives and perhaps to contribute a little good to the world.
The 1996 "Living High and Letting Die" was the result of this direction of his thought. Subtitled "our illusion of innocence," the book deployed an argumentation reminiscent of the life-or-death moral thought experiments of Judith Jarvis Thomson, Frances Kamm, and many others. It found no firm basis for the common assumption that it is morally acceptable to refrain from giving a huge portion of our income and wealth to save the lives of the poor in the Third World. Inspired by Singer's "Famine, Affluence, and Morality," the book pitted one's moral intuitions in specific case studies against the general intuition that underpins our complacency toward easily preventable deaths in poor countries.
To a much greater extent than that reached by most philosophers, Unger's argument leads its readers to precepts forbidding passive behavior toward distant misery. If we would think it wrong not to pick up a hitchhiker with a wounded leg, even if picking him up would damage the upholstery in our new car, why is it morally decent, Unger asks, to forego a similar expense and let a dozen children in Africa die of malaria? The book argued for a highly demanding morality, which, like his skepticism, sat outside the general discourse in ethics. That contradicted the far more lenient view endorsed by most recent writers on the subject. Nonetheless, the book proved popular. Written for a more general audience than his other books, "Living High and Letting Die" is in its sixth printing.
Unger's most recent work, in preparation for a book that he estimates is at least three years away, represents a return to somewhat mainstream metaphysical views. As he discusses in a recent interview with The Harvard Review of Philosophy, he is now examining "scientiphical" assumptions about the universe, asking about the implications of what is perceived as commonsense metaphysics. The course of his ideas has not exactly come full circle, but it has moved back toward philosophically polite society from the period of "Why There Are No Other People."
Despite his reputation as a contrarian, he is, in conversation, self-effacing; having spent time intensely pursuing several different contradictory worldviews, he now finds himself a bit wary of total intellectual commitment to any particular conceptual scheme.
"I think philosophy is too hard for human beings, or at least for this human being," he says. But as he pursues projects perhaps less ambitious than the denial of the possibility of knowledge, his reputation as a radical skeptic lives on.
His early writings in defense of skepticism earned him his entry in Dennett's notorious Philosophical Lexicon: unger, n. Extreme epistemic undernourishment, often developing into a skeptic ulcer. "The suggestion that no one knows what he had for breakfast this morning is strictly from unger."
(Please look for "Philosophers in Conversation: Interviews from the Harvard Review of Philosophy," including an interview of Richard Rorty, to be published by Routledge Press in May 2002.)