Passage Summary: Just because we can think about things we can't see, the author claims that seeing things can't be defined by the objects themselves causing our thoughts.

Conclusion: Perception is not a specific type of relationship involving objects causing beliefs.

Reasoning: There are objects that are imperceptible but about which we still hold beliefs.

Analysis: The flaw here is a confusion of categories. The author argues that because a definition of a sub-category (Perception) doesn't cover every instance of a broader category (Beliefs), the definition must be wrong. This is like saying a 'square' cannot be defined as a 'four-sided shape with equal sides' because there are many four-sided shapes (like rectangles) that aren't squares. To parallel this, look for an argument that rejects a specific definition simply because it doesn't account for every member of a larger, related group.