Mary the Color Scientist: A Boom Crutch Unveiled

Dennett challenges the ease with which readers imagine Mary as knowing all physical facts while assuming that seeing color must reveal an additional fact. His objection targets the handling of a demanding stipulation in Jackson's knowledge argument.

Jackson's Mary scenario asks whether complete physical knowledge would leave something to learn through color experience. Dennett challenges how confidently we imagine such completeness: an ordinary expert lacking experience is easier to picture than someone possessing every relevant physical fact. Substituting the former for the latter can change the argument.

The useful move is to distinguish stipulated conditions from intuitions imported by the story. Change a detail and ask which conclusion still follows. This does not prove that Mary learns nothing or that physicalism is true; it identifies a burden of argument that a compelling imagined scene may conceal.

When to use it

Use when a vivid hypothetical is treated as decisive proof, especially when it involves idealized knowledge, prediction, or capability.

How it can help

Separate a thought experiment's stated premises from expectations imported by a familiar story. Ask whether the conclusion follows without weakening the premises.