ABSTRACT
Spinoza's parallelism of the attributes of thought and extension serves two functions. On the one hand, it is the foundation of his theory of truth — an identity theory, as it has been called. On the other, it founds an account of the relation of the human mind to the human body. One interpretation starts from the latter, and assumes that he means much what most other people mean by "mind" and "body", and that "thought" pertains to mind, and so is psychological. The interest that a person has in the wellbeing, not only of other people, but even of inanimate parts of their world, is no more problematic than their interest in the wellbeing of their own physiological parts. More central to ethics is the difference between forms of self-interest that are egoistic and forms that are not, each corresponding to a definite set of causal relations between people and the world.
