Devoir de Philosophie


Publié le 22/02/2012

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Change in general may be defined as the variation of properties (whether of things or of regions of space) over time. But this definition is incomplete in a number of respects. The reference to properties and time raises two important questions. The first concerns whether we need to specify further the kinds of properties which are involved in change. If we define change in an object as temporal variation of its properties we are faced with the problem that some properties of an object may alter without there being a consequent change in the object itself. The second question concerns the passage of time: does temporal variation constitute change only in virtue of some feature of time itself, namely the fact (or putative fact) that time passes? Some philosophers have wished to reject the notion of time's passage. Are they thereby committed to a picture of the world as unchanging?

« shape of a thing does not count as intrinsic on the above criterion since having shape is, arguably, not logically independent of the existence of the containing space. An alternative means of strengthening the Cambridge criterion employs the notion of causality.

A genuine change in an object must, on this account, involve causal consequences contiguous to the object.

This is not true of, for example, becoming an aunt or becoming famous - the effects of such 'changes' need not be near the object in question.

Instead of defining real change in terms of intrinsic properties, we could define the intrinsic properties of an object as those whose alteration must involve contiguous effects.

On this account, shape turns out, as we would expect, to be an intrinsic property of an object.

But we cannot simply define real change in x as alteration which must have effects contiguous to x.

The 'must' in italics is surely weaker than a logical must: there is no contradiction in supposing a change in mass, for example, to have no contiguous effects.

But then if 'must' means instead 'must according to physical laws' then some mere Cambridge changes would pass the causal criterion.

If x undergoes the Cambridge change of becoming less massive than some y as a result of y's increase in mass, then this must (in the physical sense) have gravitational consequences, however small, in x's vicinity.

However, the chain of events leading to these effects in x's vicinity must have started in y's vicinity, so we could modify the account as follows: a real change in an object is such that, if it has effects, these must (in the physical sense) be mediated by effects contiguous to that object. 2 Change and the passage of time In developing his famous argument for the unreality of time, McTaggart ( 1927 ) quotes, and proceeds to criticize, Russell's definition of change ( McTaggart, J.

§2 ).

McTaggart's first criticism is, in effect, that real change must involve, not difference in truth-value between different propositions, but alteration in truth-value of the same proposition.

Suppose, to use McTaggart's example, a poker is hot on Monday and cold thereafter.

Now it is true at all times that the poker is hot on that particular Monday and cold thereafter, so these facts about the poker do not change.

The only real change consists of the fact that the poker's being hot is first a present state and then a past state.

In other words, real change implies the passage of time. Why should we accept this objection of McTaggart's ? Let us describe the event of the poker's cooling down, that is its being hot at T and cold at T', as a first-order change.

Then McTaggart seems to require a second-order change: the change in the event as it shifts from future to present to past.

So it remains to be seen why someone who denies the existence of second-order change, but accepts first-order change, should be thought to be denying change altogether. McTaggart, however, has another objection.

We can construct a spatial analogue of Russell's Cambridge change: there are two spatial points, S and S', such that the proposition 'At S [for example, London] the Greenwich meridian is within the UK' is true, while the proposition 'At S' [for example, Paris] the Greenwich meridian is. »


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