An Argument for Conceptual Atomism Concepts mean lexical concepts. The units are atomic concepts. The structure of 'brown dog' is divided into 'brown' and 'dog'. However, 'brown' itself has no internal-sub-structure. 'dog' itself has no internal-sub-structure, too. Other theories accept the thought that 'brown' or 'dog' has some structures, so they reject the thought that concepts are atomic. For example, some theories of concepts might say that 'dog' is divided into 'animal', 'quadrupedal', 'mammal', and so on. They are positive to accept the structures of concepts, and they are not conceptual atomist positions. Get it?