Ryle rejects Descartes' theory of the relation between mind and body, on the grounds that it approaches the investigation of mental processes as if they could be isolated from physical processes. In order to demonstrate how this theory may be misleading, he explains that knowing how to perform an act skillfully may not only be a matter of being able to reason practically but may also be a matter of being able to put practical reasoning into action. Practical actions may not necessarily be produced by highly theoretical reasoning or by complex sequences of intellectual operations. The meaning of actions may not be explained by making inferences about hidden mental processes, but it may be explained by examining the rules that govern those actions.