Thought and purpose

The concepts of (i) being, (ii) change, (iii) causation, (iv) action, and (v) purpose are concepts of decreasing generality, in this sense: (a) each can be understood only in terms of its predecessor on the list, and (b) while the first applies to everything, the others, in order, have an increasingly narrow scope. Much Western philosophy has amounted to an attempt to reduce one or more of these to those that precede them, and thus eliminate them as concepts necessary for philosophical understanding, but all such attempts seem to have failed. Hume did not reduce (iii) to (ii), the numberless attempts to reduce (iv) to (iii) seem clearly to have failed, and, what very few seem as yet to have realized, the attempts to reduce (v) to (iv) are unpromising. Not only is agency necessary for understanding human behavior, it seems also necessary to understanding thought, and the same appears true of the concept of purpose.