This is the fifth and—I promise--last in a series of posts on philosophy. See links to first, second, third and fourth posts below. -–John Horgan

My university would never let me teach thermodynamics or chemistry, but teach freshmen philosophy? Sure, why not. Before we mull over Plato, I prime the pump by asking, What is philosophy? What do philosophers do? As the youngsters stare at me anxiously, I assure them that philosophers squabble over what they do. There’s no right answer, take a wild guess.

Finally a brave soul ventures, Philosophy searches for truth? Yes, I reply, but so does science. Both seek truth that applies not just to specific places and times but broadly, even universally. Philosophy and science were once a single enterprise, but they diverged over the past few centuries. So how do they differ today?

Eventually someone replies, Scientists do experiments? And philosophers just think about stuff? [See Postscript.] Now we're getting somewhere! I exclaim. Science addresses questions that can, in principle, be answered through empirical investigations, given sufficient resources. How old is the universe? What is matter made of? How did life emerge on Earth. How did we emerge?

Philosophy, in contrast, obsesses over mysteries that at this point, and possibly forever, cannot be empirically solved. What is real, or true, or good? Does free will exist? Does God? Many philosophers would object to this distinction, but in this class I’m the boss, I add.

Why, I ask next, philosophize if you never get anywhere? What’s the point? They’re stumped, so I tell them: philosophers protect us from our deep-rooted need to be sure about what we are and ought to be.

That’s the money shot of this series. In previous posts, I’ve considered whether philosophy is a truth-seeking method, martial art, ethical guide, art form. Philosophy is all these things, but it is, or should be, primarily an instrument of doubt, which counters our terrible tendency toward certitude.

Chalmers, in “Why Isn’t There More Progress in Philosophy?”, acknowledges that philosophers are better at toppling than erecting truth claims. He is dissatisfied with this outcome, which he calls “negative progress,” because he can’t abandon the quest for truth. Ambitious philosophers will always yearn to be system-builders, like Kant, or better yet discoverers, like Einstein and Crick.

But philosophers should be proud of their negative progress, and embrace their role as wrecking balls. [See Post-postscript.] Demolition is a noble calling, given all the harm caused by know-it-all-ness. And by harm I mean everything from over-prescription of antidepressants to genocide. [See Post-post-postscript.]

Let’s call this critical pursuit “negative philosophy.” The allusion to negative theology is deliberate. Just as negative theology exalts God by rejecting all descriptions of Him, so negative philosophy honors Truth by skewering all expressions of It. [See Post-post-post-postscript.]

Socrates invented negative philosophy--and inadvertently demonstrated why we need it. He defines wisdom as knowing how little you know, and his parable of the cave warns that we’re prisoners of our own delusions.

But the old know-nothing is really a know-it-all. He believes—he knows—that he has escaped the cave and seen the True, Good and Beautiful blazing in all their glory. Others can see the light too, if they follow his lead, and together the enlightened elite will rule the benighted masses. We need negative philosophy to save us from our saviors.

Philosophers have labored mightily to inoculate us against religious dogmatism. Spinoza and Voltaire argued for an impersonal God consistent with reason. Nietzsche pronounced God dead, and Bertrand Russell, just to be sure, drove a stake through His heart.

Today, God is still kicking, but science is the dominant mode of knowledge, with good reason, because it has given us deep insights into and power over nature. Some scientists, intoxicated by success, claim that science is revealing the Truth about, well, everything.

Militant scientism-ists overstate religion’s evils and downplay the damage done in the name of reason. Over the past century faith in pseudo-scientific ideologies—from Marxism and eugenics to free-market capitalism—has caused far more destruction than religious zealotry.

Some philosophers have reacted to science’s ascendancy by denying that science achieves durable truth. Others have gone to the opposite extreme, becoming public-relations shills for science and denigrating alternate modes of knowledge.

While avoiding either excessive skepticism or servility, philosophers should call out scientists for overreaching, especially when they promote simplistic, deterministic theories of humanity.

Example: In the 1990s Chalmers defied Francis Crick’s proclamation that we are “nothing but a pack of neurons.” Consciousness, Chalmers retorted, can’t be reduced to purely physiological processes. In the same vein: Ned Block’s dissection of genetic theories of intelligence, Jerry Fodor’s assault on evolutionary psychology, Daniel Dennett’s defense of free will, Thomas Nagel’s broadside against materialism.

Negative philosophy can also keep physicists from getting uppity. Lawrence Krauss declares in A Universe from Nothing that physics is revealing how the universe sprang from nothing. David Albert points out that a quantum field, which Krauss defines as “nothing,” ain’t.

Negative philosophy most resembles negative theology when it reminds us that our words and concepts fall far short of reality. Paul Feyerabend, when I interviewed him in 1992, ridiculed the idea that scientists can “figure out” the world. “What they figured out,” Feyerabend said, “is one particular response to their actions, and this response gives this universe, and the reality that is behind this is laughing! 'Ha ha! They think they have found me out!’” I hear you, Paul.

My negative-philosophy notion, like most of my notions, didn’t impress the pros in my philosophy salon. A critique of a truth claim, “Nigel” sternly informed me, is a truth claim. Grrr. This is the kind of sophistry that gives philosophy a bad name. Everyone knows the difference between a positive claim, like a proof of God’s existence, and a critique of that claim. Right?

But Nigel, darn him, has a point. You can’t criticize truth claims without making truth claims, and you can’t bash ethical systems without having an ethical leg to stand on. I prefer to think of these as paradoxes, not contradictions. [Post-post-post-postscript.]

But negative philosophy can be tricky, even for the greats. Karl Popper, when I mentioned that some critics found him dogmatic, pounded the table and insisted that they are wrong. Thomas Kuhn tied himself in knots trying to tell me precisely what he meant when he talked about the limits of language.

Philosophers must doubt themselves, but not so much that they despair and seek jobs at Goldman Sachs. They must also avoid skepticism so extreme that it enables fascism and the wholesale rejection of science, including global warming and the theory of evolution. They must try to make the world a better place, even though they probably won’t.

And as long as I’m laying down rules here, let me allow some positive philosophy. Yes, “moral truth” is an oxymoron, but war is clearly bad, just as slavery and subjugation of women are bad. And yet a great philosophical work on war, Michael Walzer’s Just And Unjust Wars, dismisses the end of war as a utopian dream. I wish more philosophers would argue that ending war is a moral imperative, because I’m getting nowhere.

I realize that negative philosophy resembles my style of journalism. Well, didn’t Nietzsche say philosophy is a form of self-justification? I also realize I haven’t expounded negative philosophy with anything like rigor. I could justify my slap-dash method by quoting Burton Dreben (cited by Chalmers): “Great philosophers don’t argue.”

But I am not a philosopher, let alone a great one. I am merely lazy, and as much as I love philosophy, I have other things to do, like watching The Young Pope with my girlfriend or playing pond hockey. So it’s time to end this series.

Just a final comment: After my students read the parable of the cave, I ask: Are you in the cave right now? Answers vary. Goody-goodies say college is helping them get out of the cave. Smart-asses say college is pushing them further into the cave.

The gloomy ones, with whom I identify, say if you escape one cave, you just end up in another. To console them I say: Knowing you’ll never escape the cave is a little depressing, but it’s better than not knowing, right?

Postscript: Maybe upward inflection is appropriate for philosophical reflection?

Post-postscript: My buddies Lee Vinsel and Andrew Russell, who are historians of technology, have kicked up a fuss by arguing that innovation is greatly overrated and maintenance underrated. Apparently some philosophers think innovation is overrated in their field, too. On Leiter Reports, an anonymous commenter on my philosophy series writes:

“Progress can be defined either as: 1. accumulation of new knowledge 2. maintenance of old knowledge (e.g. through recollection). I can't understand why so many academic philosophers nowadays disrespect the second kind of progress. Human history is full of dark ages of forgetfulness, in which many of the insights of the great philosophers of antiquity were lost. So much of our work, as philosophers, is the work of maintaining knowledge--and some ages in human history were good at it, while others were not. It isn't easy to preserve and sustain insights, and we shouldn't think that our culture would sustain them on its own, without philosophers. Of course, philosophers often do not realize--or, for some perverse reason don't want to recognize--that what they think and say recollects things that were said before. It is a sad sign of our times that so many philosophers overrate originality, and fail to see the value of the knowledge gained from inner self-reflection: the kind of reflection that preserves and reveals what you already (dimly) knew.”

Post-post-postscript: Re harm: Here’s a partial list of horrors fueled by certitude: the Crusades, the Inquisition, European enslavement of Africans and extermination of Native Americans, the Reign of Terror, the Holocaust, Stalin’s gulag, Mao’s Cultural Revolution, the Vietnam War, the nuclear arms race. Let’s add the U.S. “war on terror,” which since 9/11 has resulted in hundreds of thousands of civilian deaths and exacerbated Muslim militancy.

Post-post-post-postscript: Re negative theology: In 1999, researching Rational Mysticism, I attended a conference on “Mystics” at the University of Chicago, where theologians, philosophers and other scholars acknowledged the irony of discussing experiences that are by definition “ineffable,” as William James put it. “Mystical literature is that which contests its own possibility,” one speaker said. Another said he mistakenly arrived at the meeting hall a day early. Contemplating the empty hall he thought, “This is taking negative theology too far.”

Post-post-post-post-postscript: I stumbled on a paradox embedded in skepticism while writing Rational Mysticism. I began regarding my skepticism as a spiritual practice, which clears the mind of garbage, until my handling of actual garbage gave me pause. I use Hefty garbage bags, which come in a box. After I yank the last bag from the box, the box becomes trash, which I put in the bag. I sensed a riddle in the ritual, and eventually I got it: Every garbage-removal system generates garbage, and that includes meditation.

Further Philosophical Reading:

What Is Philosophy's Point?, Part 1 (Hint: It's Not Discovering Truth)

What is Philosophy's Point? Part 2. Maybe It's a Martial Art

What Is Philosophy's Point?, Part 3. Maybe It Should Stick to Ethics

What Is Philosophy's Point?, Part 4. Maybe It's Poetry with No Rhyme and Lots of Reason

The Rise of Neo-Geocentrism

The Mind–Body Problem, Scientific Regress and "Woo"

Dispatch from the Desert of Consciousness Research, Part 1

My Modest Proposal for Solving the “Meaning of Life Problem”—and Reducing Global Conflict.

Is Scientific Materialism "Almost Certainly False"?

Why I Don't Dig Buddhism

Meta-Meditation: A Skeptic Meditates on Meditation

Should the Humanities Embrace Scientism?

Can Faith and Science Coexist?

Was Philosopher Paul Feyerabend Really Science's "Worst Enemy"?

What Thomas Kuhn Really Thought about Scientific "Truth"

Is Lawrence Krauss a Physicist, or Just a Bad Philosopher?

Will This Post Make Sam Harris Change His Mind About Free Will?

We Need a New Just-War Theory, Which Aims to End War Forever