One-way view of time in the philosophy of history
- Key People:
- Henri Bergson
- Ferdinand Berthoud
- Related Topics:
- Planck time
- Hubble time
- cosmic year
- simultaneity
- present
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When the flow of time is held to be not recurrent but one-way, it can be conceived of as having a beginning and perhaps an end. Some thinkers have felt that such limits can be imagined only if there is some timeless power that has set time going and intends or is set to stop it. A god who creates and then annihilates time, if he is held to be omnipotent, is often credited with having done this with a benevolent purpose that is being carried out according to plan. The omnipotent god’s plan, in this view, governs the time flow and is made manifest to humans in progressive revelations through the prophets.
This belief in Heilsgeschichte (salvational history) has been derived by Islam and Christianity from Judaism and Zoroastrianism. Late in the 12th century, the Christian seer Joachim of Fiore saw this divinely ordained spiritual progress in the time flow as unfolding in a series of three ages—those of the Father, the Son, and the Spirit. Karl Jaspers, a 20th-century Western philosopher, discerned an “axial age”—i.e., a turning point in human history—in the 6th century bce, when Confucius, the Buddha, Zarathustra, Deutero-Isaiah, and Pythagoras were supposedly alive contemporaneously. If the axial age is extended backward in time to the original Isaiah’s generation and forward to the Prophet Muhammad’s, it may perhaps be recognized as the age in which humans first sought to make direct contact with the ultimate spiritual reality behind phenomena instead of making such communication only indirectly through their nonhuman and social environments.
The belief in an omnipotent creator god, however, has been challenged. The creation of time, or of anything else, out of nothing is difficult to imagine, and, if God is not a creator but is merely a shaper, his power is limited by the intractability of the independent material with which he has had to work. Plato, in the Timaeus, conceived of God as being a nonomnipotent shaper and thus accounted for the manifest element of evil in phenomena. Marcion, a 2nd-century Christian heretic, inferred from the evil in phenomena that the creator was bad and held that a “stranger god” had come to redeem the bad creator’s work at the benevolent stranger’s cost. Zarathustra saw the phenomenal world as a battlefield between a bad god and a good one and saw time as the duration of this battle. Though he held that the good god was destined to be the victor, a god who needs to fight and win is not omnipotent. In an attenuated form, this evil adversary appears in the three Judaic religions as Satan.
Observation of historical phenomena suggests that, in spite of the manifestness of evil, there has been progress in the history of life on this planet, culminating in the emergence of humans who know themselves to be sinners yet feel themselves to be something better than inanimate matter. Charles Darwin, in his theory of the selection of mutations by the environment, sought to vindicate apparent progress in the organic realm without recourse to an extraneous god. In the history of Greek thought, the counterpart of such mutations was the swerving of atoms. After Empedocles had broken up the indivisible, motionless, and timeless reality of Parmenides and Zeno into four elements played upon alternately by Love and Strife, it was a short step for the atomists of the 5th century bce, Leucippus and Democritus, to break up reality still further into an innumerable host of minute atoms moving in time through a vacuum. Granting that one single atom had once made a single slight swerve, the build-up of observed phenomena could be accounted for on Darwinian lines. Democritus’s account of evolution survives in the fifth book of De rerum natura, written by a 1st-century-bce Roman poet, Lucretius. The credibility of both Democritus’s and Darwin’s accounts of evolution depends on the assumption that time is real and that its flow has been extraordinarily long.
Heracleitus had seen in phenomena a harmony of opposites in tension with each other and had concluded that War (i.e., Empedocles’ Strife and the Chinese yang) “is father of all and king of all.” This vision of Strife as being the dominant and creative force is grimmer than that of Strife alternating on equal terms with Love and yin and yang. In the 19th-century West, Heracleitus’s vision was revived in the view of G.W.F. Hegel, a German idealist, that progress occurs through a synthesis resulting from an encounter between a thesis and an antithesis. In political terms, Heracleitus’s vision reappeared in Karl Marx’s concept of an encounter between the bourgeoisie and the proletariat and the emergence of a classless society without a government.
In the Zoroastrian and Jewish-Christian-Islamic vision of the time flow, time is destined to be consummated—as depicted luridly in the Revelation to John—in a terrifying climax. It has become apparent that history has been accelerating, and accumulated knowledge of the past has revealed, in retrospect, that the acceleration began about 30,000 years ago, with the transition from the Lower to the Upper Paleolithic Period, and that it has taken successive “great leaps forward” with the invention of agriculture, with the dawn of civilization, and with the progressive harnessing—within the last two centuries—of the titanic physical forces of inanimate nature. The approach of the climax foreseen intuitively by the prophets is being felt, and feared, as a coming event. Its imminence is, today, not an article of faith but a datum of observation and experience.
Arnold Joseph Toynbee The Editors of Encyclopaedia BritannicaEarly modern and 19th-century scientific philosophies of time
Isaac Newton distinguished absolute time from “relative, apparent, and common time” as measured by the apparent motions of the fixed stars, as well as by terrestrial clocks. His absolute time was an ideal scale of time that made the laws of mechanics simpler, and its discrepancy with apparent time was attributed to such things as irregularities in the motion of Earth. Insofar as these motions were explained by Newton’s mechanics (or at least could not be shown to be inexplicable), the procedure was vindicated. Similarly, in his notion of absolute space, Newton was really getting at the concept of an inertial system. Nevertheless, the notion of space and time as absolute metaphysical entities was encouraged by Newton’s views and formed an important part of the philosophy of Immanuel Kant, a German critical philosopher, for whom space and time were “phenomenally real” (part of the world as described by science) but “noumenally unreal” (not a part of the unknowable world of things in themselves). Kant argued for the noumenal unreality of space and time on the basis of certain antinomies that he claimed to find in these notions—that the universe had a beginning, for example, and yet (by another argument) could not have had a beginning. In a letter dated 1798, he wrote that the antinomies had been instrumental in arousing him from his “dogmatic slumber” (pre-critical philosophy). Modern advances in logic and mathematics, however, have convinced most philosophers that the antinomies contain fallacies.
Newtonian mechanics, as studied in the 18th century, was mostly concerned with periodic systems that, on a large scale, remain constant throughout time. Particularly notable was the proof of the stability of the solar system that was formulated by Pierre-Simon, marquis de Laplace, a mathematical astronomer. Interest in systems that develop through time came about in the 19th century as a result of the theories of the British geologist Sir Charles Lyell, and others, and the Darwinian theory of evolution. These theories led to a number of biologically inspired metaphysical systems, which were often—as with Henri Bergson and Alfred North Whitehead—rather romantic and contrary to the essentially mechanistic spirit of Darwin himself (and also of present-day molecular biology).
Contemporary philosophies of time
Time in 20th-century philosophy of physics
Time in the special theory of relativity
Since the classic interpretation of Einstein’s special theory of relativity by Hermann Minkowski, a Lithuanian-German mathematician, it has been clear that physics has to do not with two entities, space and time, taken separately, but with a unitary entity space-time, in which, however, timelike and spacelike directions can be distinguished. The Lorentz transformations, which in special relativity define shifts in velocity perspectives, were shown by Minkowski to be simply rotations of space-time axes. The Lorentz contraction of moving rods and the time dilatation of moving clocks turns out to be analogous to the fact that different-sized slices of a sausage are obtained by altering the direction of the slice: just as there is still the objective (absolute) sausage, so also Minkowski restores the absolute to relativity in the form of the invariant four-dimensional object, and the invariance (under the Lorentz transformation) of the space-time interval and of certain fundamental physical quantities such as action (which has the dimensions of energy times time, even though neither energy nor time is separately invariant).
Process philosophers charge the Minkowski universe with being a static one. The philosopher of the manifold denies this charge, saying that a static universe would be one in which all temporal cross sections were exactly similar to one another and in which all particles (considered as four-dimensional objects) lay along parallel lines. The actual universe is not like this, and that it is not static is shown in the Minkowski picture by the dissimilarity of temporal cross sections and the nonparallelism of the world lines of particles. The process philosopher may say that change, as thus portrayed in the Minkowski picture (e.g., with the world lines of particles at varying distances from one another), is not true Bergsonian change, so that something has been left out. But if time advances up the manifold, this would seem to be an advance with respect to a hypertime, perhaps a new time direction orthogonal to the old one. Perhaps it could be a fifth dimension, as has been used in describing the de Sitter universe as a four-dimensional hypersurface in a five-dimensional space. The question may be asked, however, what advantage such a hypertime could have for the process philosopher and whether there is process through hypertime. If there is, one would seem to need a hyper-hypertime, and so on to infinity. (The infinity of hypertimes was indeed postulated by John William Dunne, a British inventor and philosopher, but the remedy seems to be a desperate one.) And if no such regress into hypertimes is postulated, it may be asked whether the process philosopher would not find the five-dimensional universe as static as the four-dimensional one. The process philosopher may therefore adopt the expedient of Henri Bergson, saying that temporal process (the extra something that makes the difference between a static and a dynamic universe) just cannot be pictured spatially (whether one supposes four, five, or more dimensions). According to Bergson, it is something that just has to be intuited and cannot be grasped by discursive reason. The philosopher of the manifold will find this unintelligible and will in any case deny that anything dynamic has been left out of his world picture. This sort of impasse between process philosophers and philosophers of the manifold seems to be characteristic of the present-day state of philosophy.
The theory of relativity implies that simultaneity is relative to a frame of axes. If one frame of axes is moving relative to another, then events that are simultaneous relative to the first are not simultaneous relative to the second, and vice versa. This paradox leads to another difficulty for process philosophy over and above those noted earlier. Those who think that there is a continual coming into existence of events (as the present rushes onward into the future) can be asked “Which present?” It therefore seems difficult to make a distinction between a real present (and perhaps past) as against an as-yet-unreal future. Philosophers of the manifold also urge that to talk of events becoming (coming into existence) is not easily intelligible. Enduring things and processes, in this view, can come into existence, but this simply means that as four-dimensional solids they have an earliest temporal cross section or time slice.
When talking in the fashion of Minkowski, it is advisable, according to philosophers of the manifold, to use tenseless verbs (such as the “equals” in “2 + 2 equals 4”). One can say that all parts of the four-dimensional world exist (in this tenseless sense). This is not, therefore, to say that they all exist now, nor does it mean that Minkowski events are “timeless.” The tenseless verb merely refrains from dating events in relation to its own utterance.
The power of the Minkowski representation is illustrated by its manner in dealing with the so-called clock paradox, which deals with two twins, Peter and Paul. Peter remains on Earth (regarded as at rest in an inertial system) while Paul is shot off in a rocket at half the velocity of light, rapidly decelerated at Alpha Centauri (about four light-years away), and shot back to Earth again at the same speed. Assuming that the period of turnabout is negligible compared with those of uniform velocity, Paul, as a four-dimensional object, lies along the sides AC and CB of a space-time triangle, in which A and B are the points of his departure and return and C that of his turnaround. Peter, as a four-dimensional object, lies along AB. Now, special relativity implies that on his return Paul will be rather more than two years younger than Peter. This is a matter of two sides of a triangle not being equal to the third side: AC + CB < AB. The “less than”—symbolized < —arises from the semi-Euclidean character of Minkowski space-time, which calls for minus signs in its metric (or expression for the interval between two events, which is ds = Square root of√c2dt2 − dx2 − dy2 − dz2 ). The paradox has been held to result from the fact that, from Paul’s point of view, it is Peter who has gone off and returned, and so the situation is symmetrical, and Peter and Paul should each be younger than the other—which is impossible. This is to forget, however, the asymmetry reflected in the fact that Peter has been in only one inertial system throughout and Paul has not; Paul lies along a bent line, Peter along a straight one.
