Philosophical presentism

Augustine of Hippo proposed that the present is analogous to a knife edge placed exactly between the perceived past and the imaginary future and does not include the concept of time. Proponents claim this should be self-evident because, if the present is extended, it must have separate parts. These parts must be simultaneous if they are truly a part of the present. According to early philosophers, time cannot be simultaneously past and present and hence not extended. Contrary to Saint Augustine, some philosophers propose that conscious experience is extended in time. For instance, William James said that time is "the short duration of which we are immediately and incessantly sensible". Other early presentist philosophers include the Indian Buddhist tradition. H. Scott Hestevlod has argued for (but not endorsed) the idea that presentists may grant the present some duration, whereas the eternalists may not. Fyodor Shcherbatskoy, a leading scholar of the modern era on Buddhist philosophy, has written extensively on Buddhist presentism: "Everything past is unreal, everything future is unreal, everything imagined, absent, mental... is unreal. Ultimately, real is only the present moment of physical efficiency [i.e., causation]." According to J. M. E. McTaggart's "The Unreality of Time", there are two ways of referring to events: the 'A Series' (or 'tensed time': yesterday, today, tomorrow) and the 'B Series' (or 'untensed time': Monday, Tuesday, Wednesday). Presentism posits that the A Series is fundamental and that the B Series alone is not sufficient. Presentists maintain that temporal discourse requires the use of tenses, whereas the "Old B-Theorists" argued that tensed language could be reduced to tenseless facts (Dyke, 2004). Note that presentism is a thesis about what exists in time, rather than what time is like. The A-series does not necessarily entail presentism nor vice versa. Tim Maudlin is described (although not by himself) as an A-theorist and an eternalist, although this is an uncommon combination. Arthur N. Prior has argued against un-tensed theories with the following ideas: the meaning of statements such as "Thank goodness that's over" is much easier to see in a tensed theory with a distinguished, present now. Similar arguments can be made to support the theory of egocentric presentism (or perspectival realism), which holds that there is a distinguished, present self. Vincent Conitzer has made a similar argument connecting A-theory with the vertiginous question. According to Conitzer, arguments in favor of A-theory are more effective as arguments for the combined position of both A-theory being true and the "I" being metaphysically privileged from other perspectives. == Philosophical objections ==

One main objection to presentism comes from the idea that what is true substantively depends upon what exists (or, that truth depends or 'supervenes' upon being). According to this critique, presentism is said to be in conflict with truth-maker theory. Truth-maker theory looks to capture the dependence of truth upon being with the idea that truths (e.g., true propositions) are true in virtue of the existence of some entity or entities ('truth-makers'). The conflict arises because most presentists accept that there are evidence-transcendent and objective truths about the past (and some accept that there are truths about the future, pace concerns about fatalism), but presentists deny the existence of the past and the future. For instance, most presentists accept that it is true that Marie Curie discovered polonium, but they deny that the event of her discovery exists (because it is a wholly past event). Since the mid-1990s, truth-maker theorists have been trying to accuse Presentists with violating their principle (that truths require truth-makers) and ontologically 'cheating'. To resolve the truth-maker theorists' counter, presentists can argue that there are truth-makers for the past, but they either exist presently or outside of time. For a second option, some presentists posit the existence of "atemporal" objects which function as truth-makers, though some justification would be needed for how something outside of time would not conflict with the proposition that only present entities exist. Presentists can as well reject that propositions about the past are made true by truth-makers. However, this leaves unclear what exactly makes truths about the past true. As a result, few philosophers support this method of resolving the objection. == Ersatz Presentism ==

Presentists who make the claim that there are “atemporal” entities (atemporal in a similar sense as numbers) which are truth-making endorse a view called “ersatz presentism.” Ersatz (German for "substitute"/"alternative") presentists believe that the truth of propositions about the past like “Churchill existed” are made true by a theoretical time which is a representation of how things were (i.e. ersatz rather than concrete). In a similar way, ersatz times would exist, but not in the same sense that actual time currently exists. Rather, they would be theoretical times which represent the moment when in which the proposition was true. Ersatz presentists must, though, postulate an ordering relationship between ersatz times which is equivalent to an earlier/later-than relation (such that t1 is later than t2). == Relativity ==

Many philosophers have argued that relativity implies eternalism, the idea that the past and future exist in a real sense, not only as changes that occurred or will occur to the present. Philosopher of science Dean Rickles disagrees with some qualifications, but notes that "the consensus among philosophers seems to be that special and general relativity are incompatible with presentism". Some philosophers view time as a dimension equal to spatial dimensions, that future events are "already there" in the same sense different places exist, and that there is no objective flow of time; however, this view is disputed. Since relativity has been confirmed by experiment, and it posits that time is a coordinate or "dimension" between two points in spacetime, it gave rise to a philosophical viewpoint known as four dimensionalism. This view treats time as another dimension, just like space, but does not eliminate it. is an example of the relativity of simultaneity. Both ends of the bar pass through the ring simultaneously in the rest frame of the ring (left), but the ends of the bar pass one after the other in the rest frame of the bar (right). Observers in motion with respect to each other are said to be in different frames of reference. These observers may disagree on whether two events at different locations occurred simultaneously, which is referred to as the relativity of simultaneity. Generally, the idea of absolute time and space is considered incompatible with general relativity; there is no universal truth about the absolute position of events which occur at different times, and thus no way to determine which point in space at one time is at the universal "same position" at another time, and all coordinate systems are on equal footing as given by the principle of diffeomorphism invariance. == See also ==