Given the foundationalism that they all shared, Descartes, Locke, and Berkeley all had a problem about evidence for the existence of matter. Unlike the other two, Berkeley said that there is no evidence for it: he rejected the thesis that there is matter as being contrary to common sense, not supported by evidence, certainly false, and conceptually defective. Locke's tendency to identify qualities with ideas becomes firm, open theory for Berkeley, and has much to do with his case for immaterialism.
Keywords: Berkeley, Descartes, foundationalism, idea, immaterialism, Locke, matter, quality