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- Michael Dummett (2000). Is Time a Continuum of Instants? Philosophy 75 (4):497-515.Our model of time is the classical continuum of real numbers, and our model of other measurable quantities that change over time is that of functions defined on real numbers with real numbers as values. This model is not derived from reality or from our experience of it, but imposed on reality; and the fit is very imperfect. In classical mathematics, the value of a function for any real number as argument is independent of its value for any other argument: the analogue is Hume's doctrine that events are loose and separate. This makes continuity in the change of any quantity a contingent law of physica, rather than a conceptual necessity. The article explores alternatives to this classical model.
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Extending on an earlier paper [Found. Phys. Ltt., 16(4) 343–355, (2003)], it is argued that instants of time and the instantaneous (including instantaneous relative position) do not actually exist. This conclusion, one which is also argued to represent the correct solution to Zeno’s motion paradoxes, has several implications for modern physics and for our philosophical view of time, including that time and space cannot be quantized; that contrary to common interpretation, motion and change are compatible with the “block” universe and relativity; and that time, space, and space-time too, cannot exist. Instead, motion and change become the major players.
Part I: Dimensions of time's enigma -- Is time real? -- Eleaticism, temporality, and time -- The makings of a temporal universe -- Pastness and futurity -- Synchronicity and synchronicity -- Temporal pace and measurement -- Presentness or the present -- Aristotle's real account of time -- Parmenidean time and the impossible now -- Cosmic motion and the speed of time -- Time as the motion of the cosmos -- Time as the cosmos itself -- Time as motion and all change -- Temporal cognition and the return of the now -- Real temporality in an Aristotelian world -- Does Aristotle refute eleaticism? -- Bisection argument I -- Bisection argument II -- Bisection argument III -- Plotinus' vitalistic platonism and the real origins of time -- Temporality, eternality, and Plotinus' new metaphysic -- Plotinus' critique of Aristotelian motion -- Indefinite temporality and the measure of motion -- Plotinus' neoplatonic account of time.
In this essay, I first set out the principles of change, paying particular attention to the need for a support for all changes and to the need for prime matter. I then discuss the nature of time, arguing that time is not actually composed of durationless instants but that instants can be understood as limits to an infinite process of potential division. I then give a definition of instants in terms of intervals and propose a way of modeling them. In the next section I bring together the two previous sections by explaining change as an instantaneous process that does not involve actual instants. In the final section I draw out a larger metaphysical moral that emphasizes the role of potentiality and sees the potentiality in change and the potentiality in time as but different aspects of the same radical potentiality in nature.
This is a study of the nature of time. In it, redeploying an argument first presented by McTaggart, the author argues that although time itself is real, tense is not. He accounts for the appearance of the reality of tense - our sense of the passage of time, and the fact that our experience occurs in the present - by showing how time is indispensable as a condition of action. Time itself is further analysed, and Dr Mellor gives answers to most of the metaphysical questions it provokes, concerning the relation of time to space, the dissection of time, and its relation to change and causation.
A version of nonstandard analysis, Internal Set Theory, has been used to provide a resolution of Zeno's paradoxes of motion. This resolution is inadequate because the application of Internal Set Theory to the paradoxes requires a model of the world that is not in accordance with either experience or intuition. A model of standard mathematics in which the ordinary real numbers are defined in terms of rational intervals does provide a formalism for understanding the paradoxes. This model suggests that in discussing motion, only intervals, rather than instants, of time are meaningful. The approach presented here reconciles resolutions of the paradoxes based on considering a finite number of acts with those based on analysis of the full infinite set Zeno seems to require. The paper concludes with a brief discussion of the classical and quantum mechanics of performing an infinite number of acts in a finite time.
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A version of nonstandard analysis, Internal Set Theory, has been used to provide a resolution of Zeno's paradoxes of motion. This resolution is inadequate because the application of Internal Set Theory to the paradoxes requires a model of the world that is not in accordance with either experience or intuition. A model of standard mathematics in which the ordinary real numbers are defined in terms of rational intervals does provide a formalism for understanding the paradoxes. This model suggests that in discussing motion, only intervals, rather than instants, of time are meaningful. The approach presented here reconciles resolutions of the paradoxes based on considering a finite number of acts with those based on analysis of the full infinite set Zeno seems to require. The paper concludes with a brief discussion of the classical and quantum mechanics of performing an infinite number of acts in a finite time.
Dummett in his recent paper in Philosophy replies in the negative to the question, “Is time a continuum of instants?” But Dummett seems to think that this negative reply entails giving an alternative theoretical account; he nowhere canvasses the possibility that there is something amiss with the question. In other words, Dummett thinks that he still has to reply to the question, “What (then) is time?” I offer no answer whatsover to such ‘questions’. Rather, I ask what it could possibly mean to say that time is (e.g.) a continuum of instants (and by extension, whether it can mean anything at all to assert that it isn't). In the course of doing so, I suggest that Dummett's ‘Anti-Realism’ is invariably a form of Realism, just a subtly inconsistent form. Anti-Realism keeps the fundamental metaphysical picture of Realism intact. Anti-Realism still thinks that there is a Reality...settling whether Realism or Anti-Realism is correct! ‘Anti-Realism’ is never anti-Realist enough.
Ulrich Meyer's objections to Dummett's arguments on the time continuum fail because he takes Dummett to endorse Hume's atomistic doctrine that events are ‘loose and separate’, In fact, Dummett rejects this doctrine. He used it in his original article only to indicate that certain implications which are conceptually possible fom the point of view of the classical model of time are not actually conceptually possible.
In a recent article (‘The Continuum: Russell’s Moment of Candour’), Christopher Ormell argues against the traditional math- ematical view that the real numbers form an uncountably infinite set.1 He rejects the conclusion of Cantor’s diagonal argument for the higher, non-denumerable infinity of the real numbers. He does so on the basis that the classical conception of a real number is mys- terious, ineffable, and epistemically suspect. Instead, he urges that mathematics should admit only ‘well-defined’ real numbers as proper objects of study. In practice, this means excluding as inadmis- sible all those real numbers whose decimal expansions cannot be calculated in as much detail as one would like by some rule.
Michael Dummett claims that the classical model of time as a continuum of instants has to be rejected. In his view, “it allows as possibilities what reason rules out, and leaves it to the contingent laws of physics to rule out what a good model of physical reality would not even be able to describe.” This paper argues otherwise.
Discussion of Michael Dummett, Is time a continuum of instants?
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