T is a widely held view that the passage of time necessarily involves
change in such a way that there cannot be an interval
of time in which no changes whatever occur. Aristotle spoke
of time as "a kind of affection of motion," and said that, although
time cannot be simply equated with motion or with change, "neither
does time exist without change." 1 Hume claimed that "'tis
impossible to conceive .. . a time when there was no succession or
change in any real existence." 2 And McTaggart presented as something
"universally admitted" the contention that "there could be
no time if nothing changed" (from which, he claimed, it follows
that everything is always changing, at least in its relational qualities).
3 Similar claims can be found in the works of contemporary
writers.4
The claim that time involves change must of course be distinguished
from the truism that change involves time. And, as it will
be understood in this paper, it must also be distinguished from a
truism that Aristotle expressed by saying "if the 'now' were not
different but one and the same, there would not have been time,"
i.e., the truism that if at time t' some time has elapsed since time
t, then t' is a different time than t.5