TB: The Philosophy of Bah (Caplan)
Core Thesis
Bryan Caplan rebrands Mike Huemer's intuitionism — itself a rebadging of the older "philosophy of common sense" — as the Philosophy of Bah: when an argument's conclusion is glaringly false, the right move is to reject one of its premises rather than accept the absurdity. Demanding proofs of the obvious is a confusion about what proofs are for.
Key Takeaways
Proofs run from the more obvious to the less
- "The point of a proof is to move from more obvious propositions to less obvious propositions. So demands for 'proof' of the most obvious propositions are confused."
- Self-evident propositions are the input to philosophy, not its output. Demanding to derive them from something even more secure is asking philosophy to bootstrap itself out of nothing.
The contrapositive is your friend
- A valid argument with an obviously false conclusion tells you at least one of its premises is wrong. The Philosophy of Bah is the trained reflex to take that exit rather than swallow the absurdity.
- "It allows us to reject any valid argument that implies a glaring falsehood." This is not anti-rationalism; it is the standard move in mathematics (reductio ad absurdum), promoted to a general epistemic stance.
Defense, not offense
- "The point of the Philosophy of Bah is not to convince others of the obvious, but to convince yourself of the obvious." It is intellectual armor for the curious — a way to engage clever arguments without being paralyzed by them.
- Caplan's preemptive reply to the dogmatism charge: "I'm not dogmatic; you're gullible."
John's notes — the live tension
John takes the Bah position seriously and presses on it:
- Intuitionism feels like the obvious default position — every philosophical move ultimately rests on something taken as self-evident.
- But the whole project of science and philosophy seems to be the business of transcending first-pass intuition. So how can both be true?
- Resolution attempt: the override is paid for by explanatory power. See BeginningOfInfinity — good explanations earn the right to overturn intuition.
- Companion frame: Explanation is what matters.
- Wittgenstein's tractatus image: maybe the axioms are like the ladder you throw away once you've climbed.
- The open question John flags as Big: when should intuitionism be overridden, and how do we diagnose those cases?
- Counter-examples to a naive Bah: heliocentrism, the round earth, the moral equality of races, galaxies, Many-Worlds QM. All started by sounding "Bah!"-worthy and ended up correct.
- But Huemers Proof of free will uses intuitionism the way Caplan recommends — and John finds the argument formally circular even while liking the move.
- The problems of philosophy — same family of questions about the limits of intuition.
Mental Models
- First Principles Thinking — Bah is what a first principle looks like in practice: a stopping point you do not try to derive
- Inversion — denying the conclusion to deny a premise is inversion as an epistemic discipline
- Occam's Razor — between "the obvious is false" and "this argument has a hidden bad premise," prefer the simpler hypothesis
- Long Chains of Complex Reasoning Are Brittle — Bah is the empirical observation that long arguments to absurd conclusions usually broke somewhere
See also
- Huemer's Proof of Free Will — Huemer applying intuitionism to free will; John's circularity worry is exactly the question of when the move is legitimate
- The Wages of Sin (Huemer / Fake Nous) — same intuitionist style turned on moral psychology
- Knowledge, Reality and Value (Huemer) — book-length treatment of the same epistemic stance
- Philosophy and Epistemology — common-sense intuitions as ground truth; radical skepticism as probe not conclusion
Source
Bryan Caplan, Bet On It Substack, 2026 Original article