time slice a temporal part or stage of any concrete particular that exists for some interval of time; a three-dimensional cross section of a fourdimensional object. To think of an object as consisting of time slices or temporal stages is to think of it as related to time in much the way that it is related to space: as extending through time as well as space, rather than as enduring through it. Just as an object made up of spatial parts is thought of as a whole made up of parts that exist at different locations, so an object made up of time slices is thought of as a whole made up of parts or stages that exist at successive times; hence, just as a spatial whole is only partly present in any space that does not include all its spatial parts, so a whole made up of time slices is only partly present in any stretch of time that does not include all its temporal parts. A continuant, by contrast, is most commonly understood to be a particular that endures through time, i.e., that is wholly present at each moment at which it exists. To conceive of an object as a continuant is to conceive of it as related to time in a very different way from that in which it is related to space. A continuant does not extend through time as well as space; it does not exist at different times by virtue of the existence of successive parts of it at those times; it is the continuant itself that is wholly present at each such time. To conceive an object as a continuant, therefore, is to conceive it as not made up of temporal stages, or time slices, at all. There is another, less common, use of ‘continuant’ in which a continuant is understood to be any particular that exists for some stretch of time, regardless of whether it is the whole of the particular or only some part of it that is present at each moment of the particular’s existence. According to this usage, an entity that is made up of time slices would be a kind of continuant rather than some other kind of particular.
Philosophers have disputed whether ordinary objects such as cabbages and kings endure through time (are continuants) or only extend through time (are sequences of time slices). Some argue that to understand the possibility of change one must think of such objects as sequences of time slices; others argue that for the same reason one must think of such objects as continuants. If an object changes, it comes to be different from itself. Some argue that this would be possible only if an object consisted of distinct, successive stages; so that change would simply consist in the differences among the successive temporal parts of an object. Others argue that this view would make change impossible; that differences among the successive temporal parts of a thing would no more imply the thing had changed than differences among its spatial parts would.
See also METAPHYSICS , WHITEHEAD. P.F.