 On Price’s line of thought, perceptual experiences do afford us with some certainty. When Price sees a tomato, he may be certain that there is something red and round present. According to critics of the argument, Price is not entitled to be certain of any such thing. For example, his experience might merely represent that there exists something red and round present, where such representation can occur even if nothing red and round is present (for more on this objection see the entry on  the problem of perception  (section 3.1.2).