The first avowed skeptics — they identify a real problem with the senses, draw the wrong conclusion, and build an ethics of whim-worship and brute force on top of it.
Source: YouTube (32:06) Links: Series Index, Episode 6: Pluralists & Atomists
Peikoff opens by clarifying that the Sophists weren’t a philosophical school but a professional class in 5th century BC Athens. Sophia means wisdom; a Sophist is etymologically a “wise man.” But what they taught was how to win friends, flatter the multitude, and gain political power. They trained unscrupulous office-seekers in debating tricks, fallacies, and rhetorical gimmicks — “debased Dale Carnegies on the political level.”
Their reputation suffered partly for legitimate reasons and partly unfairly. One source of opprobrium: they charged money for teaching philosophy, which was considered a breach of principle (a bias Peikoff notes persists in universities).
The major figures: Protagoras (480-410 BC), the father of sophism, and Gorgias (483-375 BC). Also Thrasymachus and Callicles.
The Sophists are the first avowed skeptics in philosophy. Their central claim: no objective or certain knowledge is possible to anyone about anything.
Peikoff distinguishes their argument from weaker, “Reader’s Digest” versions of sense-skepticism:
These are poor arguments that “wouldn’t stop anybody seriously for five minutes.” The Sophists used these but their real case was much deeper.
The core argument: Whenever we perceive, what we perceive depends on two factors:
Examples given:
The conclusion: since your sensory apparatus always shapes what you perceive, you never perceive reality directly. All you ever know is “how reality appears to us because of our senses.” You can never say “it is” — only “it seems to me, now.”
Peikoff stresses this is the most influential argument ever advanced against the senses — accepted by Plato, the entire Christian era, “almost all modern philosophers without exception,” and forming the basis of Kant’s entire philosophy. He flags it as urgently important to know what’s wrong with it, but leaves the refutation for the audience to work out.
Having attacked the senses, the Sophists extend the assault to reason:
Reason depends on sensory evidence (which the Sophists say is correct — reason needs input from the senses). If the input is subjective, so are the conclusions.
The argument from disagreement: Thales says water, Heraclitus says fire, Parmenides says no change, Pythagoras says numbers, the atomists say particles — if reason could reach truth, philosophers would agree. They don’t, so reason can’t. Peikoff calls this “enormously widespread” and “almost as widespread as it is fallacious.”
Heraclitean flux: Everything is constantly changing. Even if you stumbled on truth by luck, it wouldn’t stay true for two consecutive instants.
Protagoras: “Man is the measure of all things — of things that are, that they are; and of things that are not, that they are not.” By “man” he means each individual, subjectively. If you feel something is so, it is so for you. Complete subjectivism and relativism.
Gorgias: Wrote a book titled On Nature, or the Non-Existent, maintaining three propositions:
Peikoff notes the futility of challenging such a position — the skeptic retreats into “it’s highly probable that it’s highly probable that nothing exists” ad infinitum. The ancients called this reductio ad absurdum — reduction to babbling.
Since neither reason nor God can ground ethics (they’re agnostics, not atheists — atheism claims to know there’s no God), the Sophists conclude: there is no objective ethics. It comes from nowhere.
The ethical framework that follows:
When desires conflict with other people, the only recourse is brute physical force. Reason is useless for persuasion (by their own arguments), so the only argument is a club.
Thrasymachus is the principal advocate: might makes right. The only problem with lying, cheating, robbing, raping, and murdering is getting caught.
Two strategies for the aspiring Sophist egoist:
Plato presents the Sophist position through the myth of Gyges — a shepherd who discovers a ring that makes him invisible. The Sophists say: with this ring, everyone would run riot. The “just” man would behave exactly like the unjust man. Society’s rules exist only because people are afraid — if they could act without consequences, they’d all satisfy every desire by force.
Thrasymachus (in Plato’s dialogue): “No one it is commonly believed would have such iron strength of mind as to stand fast in doing right or keep his hands off other men’s goods when he could go to the marketplace and fearlessly help himself to anything he wanted.”
Peikoff makes what he considers an important historical point: egoism as a philosophical position was born tied to skepticism, whim-worship, and brutality. Because the Sophists were the first egoists AND they abandoned reason, egoism acquired the image of arbitrary, brutish self-interest.
Aristotle was an egoist of a “radically different kind,” but Christianity had an interest in ignoring Aristotle’s version and presenting sophism as the only possible egoism. The result: to this day, “selfish” is taken as a synonym for “brute whim-worshipper.”
Peikoff identifies a recurring pattern: constructive philosophical era → collapse into skepticism → new constructive era, paralleling economic boom-bust cycles. The Sophists mark the end of the pre-Socratic constructive period. Since people can’t live by skepticism, a new philosopher of great importance always appears — in this case, Plato (and later Aristotle).
He extends this to the present: 20th century skepticism has reached “the most intense level ever,” which he says “augurs well for the future of a new constructive period.”
In response to a question, Peikoff explains why the Greeks sided with reason over the senses (rather than the reverse, as Hume later would). His answer: if you must be wrong about one, abandoning the senses is less catastrophic than abandoning reason. A rationalist who mistrusts the senses can still think — he’ll reach wrong conclusions, but he continues intellectual development. An empiricist who mistrusts reason (like Hume) “is in the position of an animal or a skeptic” — knowledge halts entirely.
The pattern through history: skeptics destroy everything, then a new rationalist appears to rebuild — Sophists → Plato, later skeptics → Augustine, Renaissance skeptics → Descartes, Hume → Kant. The skeptics “simply set up the next rationalist.”
The sensory argument is presented with genuine force. Peikoff doesn’t strawman the Sophists. He explicitly distinguishes their deep argument (perception always depends on the apparatus) from the shallow versions (illusions, hallucinations) and calls it the most influential argument ever against the senses. This is intellectually honest — he’s presenting the strongest version of the position he disagrees with.
The ethics follow logically from the epistemology. Peikoff traces the chain clearly: if senses fail → reason fails → no objective knowledge → no objective ethics → whim-worship → brute force. Each step follows from the previous one. You can see exactly where the error compounds.
The egoism-tragedy observation is insightful. The historical point that egoism was first formulated by people who had abandoned reason, permanently associating self-interest with brutishness, is a genuinely illuminating observation about how philosophical reputations get fixed. Whether or not you agree with Peikoff’s preferred alternative (rational egoism), the historical point stands.
The boom-bust cycle parallel is provocative. Comparing philosophical cycles (construction → skepticism → reconstruction) to economic boom-bust cycles is a striking analogy. Whether it holds up under scrutiny is debatable, but it’s a useful framing device for understanding the rhythm of philosophical history.
The sensory argument refutation is left as an exercise. Peikoff says it’s “urgently important” to know what’s wrong with the argument, then explicitly doesn’t answer it. He invites the audience to think about it. This is pedagogically interesting but also potentially frustrating — and it means the strongest argument in the lecture goes unaddressed. His hint (“two things are true and can’t be contested”) suggests the answer involves accepting both premises but denying the conclusion follows, though he doesn’t spell out how.
The argument from disagreement is dismissed too quickly. Peikoff calls it “almost as widespread as it is fallacious” but doesn’t explain the fallacy. This matters because the argument from disagreement is genuinely persuasive to many people and deserves a clear rebuttal, not just a dismissal.
“Partly undeserved” reputation goes unexplored. Peikoff opens by saying the Sophists’ bad name is partly undeserved, then spends the entire lecture demolishing them. He never returns to what’s deserved in their reputation or what insights they contributed. The sensory apparatus argument identifies something genuinely important about perception — even if the conclusion is wrong, the observation is real. This goes unacknowledged.
The Objectivist lens shows most clearly in the egoism section. Peikoff’s concern that egoism got a bad name is clearly motivated by Objectivism’s project of rehabilitating rational self-interest. This doesn’t make the observation wrong, but it’s worth noting that the emphasis reflects his particular philosophical commitments. A non-Objectivist lecturer might not spend as much time on this point.
The claim about “most modern philosophers” accepting the sensory argument is sweeping. Peikoff says the argument was accepted by “almost all modern philosophers without exception.” This is a strong claim that could use qualification. Many modern philosophers (pragmatists, naturalized epistemologists, direct realists) would dispute that they accept the Sophist argument, even if they acknowledge the apparatus-dependence of perception.
On the sensory apparatus argument: The Sophists identified something real — perception IS apparatus-dependent. Modern neuroscience confirms this extensively. Color perception depends on cone cells (some people have four types, most have three, some have two). The question of whether this means we “never perceive reality” or simply “perceive reality through a particular interface” remains live in philosophy of perception. Direct realism, indirect realism, and representationalism are all active positions.
On the argument from disagreement: Still enormously popular and still fallacious. The existence of disagreement among experts proves neither that truth is unreachable nor that all positions are equally valid. Scientists disagreed about continental drift for decades; that didn’t make the continents stop moving. The fallacy is assuming that the absence of consensus implies the absence of fact.
On ethical subjectivism: The Sophists’ ethical position has been enormously influential — arguably more so than their epistemology. The chain from “no objective knowledge” to “no objective ethics” to “might makes right” has been replayed by Machiavelli, Hobbes, Nietzsche, and various 20th century thinkers. Whether ethical objectivism can be grounded without the problems the Sophists identified remains one of the central questions in moral philosophy.
On egoism: The Sophists’ version — arbitrary desire + brute force — is indeed what most people mean by “egoism.” Whether a rational, non-arbitrary egoism is possible (as Peikoff/Rand claim via Objectivism, or as Aristotle arguably demonstrated) is a separate question. But the Sophists’ version is clearly self-defeating: a society of Sophist egoists would destroy itself immediately, which means even the egoist has rational reasons to not be this kind of egoist.
On the philosophical cycle: The pattern Peikoff identifies (construction → skepticism → reconstruction) does appear in the historical record, though whether it’s a genuine cycle with predictive power or just a narrative imposed after the fact is debatable. The parallel to economic cycles is suggestive but unproven.
On “man is the measure”: Protagoras’s statement has had a remarkable afterlife. It was revived by Renaissance humanism (in a positive sense), adopted by pragmatism (in a modified sense), and forms the implicit foundation of much contemporary relativism. The phrase means very different things depending on who’s using it — which is itself a demonstration of the Sophist problem.
[To be added in a separate pass]