PLANNED ACTION, ACTION IN SPITE OF INTERNAL CONFLICT, AND ACTION AGAINST EXTERNAL OBSTRUCTION
If the psychologist were required to begin his chapter on the will with a clean-cut definition, he would be puzzled what to say. He might refer to the old division of the mind into the "three great faculties" of intellect, feeling, and will, but would be in duty bound to add at once that this "tripartite division" is now regarded as rather useless, if not misleading. It is misleading if it leads us to associate will exclusively with motor action, for we also have voluntary attention and voluntary control in reasoning and inventing, and we have involuntary motor reactions. "Will" seems not to be any special kind of response, but rather to refer to certain relationships in which a response may stand to other responses--but this is certainly too vague a definition to be of use.
"Will" is not precisely a psychological term, anyway, but is a term of common speech which need not refer to any psychological unit. In common speech it has various and conflicting meanings. "Since you urge me", one may say, "I will do this, though much against my will." Let the dictionary define such words. What psychology should do with them is simply to take them as a mining prospector takes an outcropping of ore: as an indication that it may pay to dig in the neighborhood.