Defends Reid's Common Sense philosophy against the claim that perception does not allow us to experience the physical world With a new reading of Thomas Reid on primary and secondary qualities, Christopher A. Shrock illuminates the Common Sense theory of perception. Shrock follow's Reid's lead in defending common sense philosophy against the problem of secondary qualities, which claims that our perceptions are only experiences in our brains, and don't let us know about the world around us. At the same time, Schrock maintains a healthy optimism about science and reason.