Testing the theory of forms › Thoughts and patterns do not end the inquiry

Socrates tries another proposal: perhaps Forms are thoughts existing in souls. Parmenides asks whether a thought must be a thought of something, and whether the common object recognized by it would itself be the Form. He also presses the consequences of saying that things participate in thoughts. The proposal therefore has not simply eliminated the original issue by relocating the Form inside a mind (132b–c).

The distinction matters beyond the immediate exchange. The act of thinking about a common property and the property thought about need not be the same thing. Calling an explanation "a concept" leaves open whether the concept merely records a similarity, creates a classification, or identifies something independent of the act. Those alternatives require argument. They cannot be decided simply by replacing the word "Form" with "thought."

Socrates next proposes that Forms are patterns and participants are likenesses of them. Parmenides replies that resemblance is reciprocal: if a thing resembles the pattern, the pattern resembles the thing. If things that resemble each other require a common Form, the pattern and its likeness require another Form, producing another regress (132c–133a).

Here the difficulty concerns the attempt to explain participation entirely through resemblance. An original and its copy may have different roles, but resemblance alone does not explain that difference. A photograph may resemble a face without the face being a copy of the photograph. The modern example illustrates the difference between reciprocal similarity and an asymmetric explanatory relationship; it does not supply a theory of Forms. A defender needs an account of the relevant asymmetry, rather than the word "pattern" alone.