ABSTRACT
Change, according to this picture, consists in the realization or actualization of some of these potentialities. These realizations in their turn consist again of dispositions or potentialitiespotentialities, though, that differ from those whose realizations they are. This view corresponds closely to the commonsense view of the world. When a student enters the university there is a certain possibility inherent in this situation of his sitting his finals; of his answering the examination questions more or less successfully; and of his obtaining a degree. When he sits his finals he is realizing the first of these possibilities or potentialities; and at the same time, the new situation which has arisen changes the other two possibilities. In fact, the sitting of his finals can be said to be essentially a possibility of his answering examination questions more or less successfully, and of obtaining his degree. When he has given his answers, and when he has thus realized another set of possibilities or
potentialities, a new situation has been created which again changes the potentialities of his obtaining a degree. When he ultimately gets his degree, and thus again realizes certain potentialities, then the new situation creates new potentialities-relating, say, to his making use of his degree, or not making use of it, in his career. We thus obtain a picture of the world which is at once dualistic and monistic. It is dualistic in that the potentialities are potentialities only relative to their possible realizations or actualizations; and it is monistic in that the realizations or actualizations not only determine potentialities, but may even be said to be potentialities themselves. (But we should perhaps avoid saying that they are 'nothing but' potentialities.) Thus we may describe the physical world as consisting of changing propensities for change. Although these propensities do not in general determine future changes, they may determine, in some fields of physics at least, the probability distributions-which may include probabilities equal to 1-of the various possible future changes.
