Change (philosophy)

Change refers to a difference in a state of affairs at different points in time. Although it is a familiar experience, an analysis of change provides subtle problems which have occupied philosophers since the Presocratics.Heraclitus is the first philosopher known to have directly raised such issues, with aphorisms such as "one cannot step into the same river twice". The Eleatics were particularly concerned with change and raised a number of problems, including Zeno's paradoxes, which caused them to go as far as insisting that change was impossible, and that reality was one and unchanging. Later philosophers would reject this conclusion, instead developing systems such as atomism in attempts to circumvent the Eleatic problems. In the modern era, some of these problems would enter the domain of mathematics, with the development of calculus and analysis. These developments were regarded by some as solving problems of change, but others maintain that philosophical issues persist.

The Chinese philosophy of change was described in centuries of commentary on the I Ching, the Book of Changes.

Heraclitus is the first philosopher for whom there exists an extant written account of an enquiry into change. Writing in an aphoristic and esoteric style, Heraclitus remarked that, "On those stepping into rivers staying the same other and other waters flow". Or, more popularly: "One cannot step into the same river twice." This is generally taken to refer to the seeming contradiction between our calling the river "the same", while knowing that the material constituents of the river, the "waters", have completely changed. (A later follower amended the final word in the saying from "twice" to "once".)

It is unclear what reaction Heraclitus intends to induce by this statement, and he provides no exposition. It is however but one of many examples of a more general theme which Heraclitus termed the "unity of opposites" - the fact that opposing predicates could be asserted of the same thing, another example being, "the road up and the road down is one and the same".

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