Knowledge and purpose as habit mechanisms.

I t is only with the greatest difficulty that scientists are able to maintain a thoroughly naturalistic attitude toward the more complex forms of human behavior. Our intellectual atmosphere is still permeated in a thousand subtle ways with the belief in disembodied behavior functions or spirits. The situation is aggravated by the fact that the details of the more complex action patterns are so concealed as to be almost impossible of observation. Even so, the outlook is hopeful. The work of many ingenious investigators is bringing to light important details of the hidden processes, and enough evidence has already accumulated to enable us in a number of cases to discern with tolerable clearness the broad naturalistic outlines of their operation.