mechanistic explanation a kind of explanation countenanced by views that range from the extreme position that all natural phenomena can be explained entirely in terms of masses in motion of the sort postulated in Newtonian mechanics, to little more than a commitment to naturalistic explanations. Mechanism in its extreme form is clearly false because numerous physical phenomena of the most ordinary sort cannot be explained entirely in terms of masses in motion. Mechanics is only one small part of physics. Historically, explanations were designated as mechanistic to indicate that they included no reference to final causes or vital forces. In this weak sense, all present-day scientific explanations are mechanistic. The adequacy of mechanistic explanation is usually raised in connection with living creatures, especially those capable of deliberate action. For example, chromosomes lining up opposite their partners in preparation for meiosis looks like anything but a purely mechanical process, and yet the more we discover about the process, the more mechanistic it turns out to be. The mechanisms responsible for meiosis arose through variation and selection and cannot be totally understood without reference to the evolutionary process, but meiosis as it takes place at any one time appears to be a purely mechanistic physicochemical process. Intentional behavior is the phenomenon that is most resistant to explanation entirely in physicochemical terms. The problem is not that we do not know enough about the functioning of the central nervous system but that no matter how it turns out to work, we will be disinclined to explain human action entirely in terms of physicochemical processes. The justification for this disinclination tends to turn on what we mean when we describe people as behaving intentionally. Even so, we may simply be mistaken to ascribe more to human action than can be explained in terms of purely physicochemical processes. See also BEHAVIOR- ISM , EXPLANATION , PHILOSOPHY OF MIN. D.L.H.