ABSTRACT
The doctrine of physicalism, so understood, must be compatible with the observation that there are differences as well as similarities among the things that exist. Reduction is exemplified by the relation between the macroscopic substance property water, and the micro-structural property H2O. Realization is a relationship that holds, not between two properties at different levels of aggregation, but rather between properties at different levels of abstraction. Realization involves functional or structural properties, like ion or cell, properties that capture abstract dimensions of similarity among things that may vary considerably in their composition. Intentionality involves normativity, another anomaly from the physicalistic point of view. Some mental states like perceptual states and beliefs, represent things as being a certain way. The essential role of intentionality in our mental life provides another explanation of the failure of behaviorism. The problems for the doctrine posed by the phenomenon of mentality are serious, and may be intractable.
