Paul Graham's mechanism, applied by Marshall to philosophy as a field: > "When things are hard to understand, people who suspect they're nonsense generally keep quiet. There's no way to prove a text is meaningless. The closest you can get is to show that the official judges of some class of texts can't distinguish them from placebos." The dynamic: 1. A field produces work that "sounds profound" and can't be straightforwardly disproven. 2. Smart readers who suspect nonsense have no way to *prove* it — the texts are ambiguous enough to survive any critique. 3. Those smart readers go silent and quietly study other things instead. 4. The people who *remain* are believers and the credulous. 5. Standards drift further; more nonsense gets published; more suspecting smart people leave. 6. The field self-perpetuates as nonsense — the correctors have all evaporated. Marshall's diagnosis: academic philosophy is in late-stage evaporative cooling. The people best equipped to do philosophy are in physics, programming, finance, engineering. The "official" field has been left to those who couldn't or didn't notice. **Exception clause Marshall flags**: formal logic (essentially math) and philosophy of mind (rapidly becoming neuroscience) have *not* cooled — both retain consequence-bearing structure. Math doesn't tolerate handwaving; neuroscience has experimental feedback. Cooling hits the branches that severed from any check on whether they're right. General lesson: when smart practitioners have quietly left and only true believers remain, the field has already cooled. Reverse heuristic: sub-fields with tight feedback resist cooling even when the parent field has decayed.