What philosophical position did Berkeley reject from Locke?

Berkeley's rejection of dualism stems from his idealist perspective, which fundamentally challenges the notion of a material substance existing independently of perception. Dualism, as proposed by thinkers like Descartes, posits that there are two distinct kinds of substances: mental (mind) and physical (body). Berkeley, however, argued that only immaterial substances exist, asserting that physical objects do not have an existence outside of being perceived. In his view, "to be is to be perceived," emphasizing that the existence of objects is dependent on their perception. This philosophical stance directly opposes dualism by denying the reality of a physical substance that exists independently of the observer. Berkeley's emphasis on idealism leads him to dismiss the dualistic framework of separating mind and matter, highlighting his commitment to a philosophy that centers on perception and immaterialism.