Document Type : Research Paper

Author

• Hassan Amiriara

Ph.D., Philosophy of Science, Iranian Institute of Philosophy,

Abstract

There are two main camps in 20th-century philosophy of time: A-theorists who believe in the dynamic model of reality, and B-theorists who maintain a static model of reality. After the publication of Putnam’s influential article, “time and physical geometry” (1967), the implications of the Special Theory of Relativity became serious in metaphysical discussions about temporal reality. Some philosophers argued that this theory contradicts the dynamic model and implies the ontology of the static model, namely, the objective reality of the present, past and future events. In response, some advocates of the dynamic model argued that there can be dynamic models in relativistic setting, though they are different, radically, from old theories of dynamic reality. In this paper, first, I shall discuss how special relativity contradicts the traditional dynamic model and, then, how new dynamic models imply a relative concept of reality, in contrast to its old absolute concept and, so, why these strategies are very unintuitive. Finally, I shall argue that this radical conceptual shift about reality is, not only unintuitive, but unwarranted and, in some sense, inconsistent as well.

Highlights

On Reality of Events in the Philosophy of Time

An Examination of the Notion of Relative Reality in 20th-Century Debate about Inconsistency of Dynamic Models and Special Theory of Relativity

Hassan Amiriara

Ph.D., Philosophy of Science, Iranian Institute of Philosophy, Email:h.amiriara@gmail.com

Abstract

There are two main camps in 20th-century philosophy of time: A-theorists who believe in the dynamic model of reality, and B-theorists who maintain a static model of reality. After the publication of Putnam’s influential article, “time and physical geometry” (1967), the implications of the Special Theory of Relativity became serious in metaphysical discussions about temporal reality. Some philosophers argued that this theory contradicts the dynamic model and implies the ontology of the static model, namely, the objective reality of the present, past and future events. In response, some advocates of the dynamic model argued that there can be dynamic models in relativistic setting, though they are different, radically, from old theories of dynamic reality. In this paper, first, I shall discuss how special relativity contradicts the traditional dynamic model and, then, how new dynamic models imply a relative concept of reality, in contrast to its old absolute concept and, so, why these strategies are very unintuitive. Finally, I shall argue that this radical conceptual shift about reality is, not only unintuitive, but unwarranted and, in some sense, inconsistent as well.

Keywords: Dynamic model of reality, Becoming, Minkowski Spacetime, Special Theory of Relativity, Relative reality.

Introduction

Since the publication of McTaggart’s article about the nature of time, “The Unreality of Time” (1908), discussions over the ontology of temporal events became serious in the literature of the contemporary metaphysics. McTaggart introduces two main temporal structures for events. The first is, as he calls, A-determinations, namely the past, the present, and the future. And the second is B-relations, i.e. being before, being simultaneous and being future. With this distinction, we can distinguish between two general ontology of time:

a) The Dynamic Model (or A-theory): there is an absolute and general distinction between A-determinations in reality.

b) The Static Model (or B-theory): there is no absolute and general distinction between A-determinations in reality, but events are only ordered objectively via B-relations.

The question of which model described above is the true model of ontology was mainly a metaphysical question. However, after the publication of Hillary Putnam’s article i.e. “Time and Physical Geometry” (1967), philosophers gradually paid serious attention to metaphysical implications that the Special Theory of Relativity might have for the ontology of time. In his article, Putnam argued that the relativity of simultaneity suggests the reality of all events (i.e. past, present, and future). If Putnam’s argument succeeds, then there should be a third ontology of time:

c) There is neither absolute distinction between A-determinations nor the genuine B-relation structure of events, for the relativity of simultaneity contradicts the absoluteness of B-relations.

In doing so, he introduced a relation, known as the relation of reality, or R. in section 3, I will discuss this relationship in some detail. For now, it should be said that Putnam thinks that this relation must be an equivalence relation. In section 6 I will try to show that equivalency of this relation has an intimate connection with the absoluteness of the ontology. I will argue, if the relation R, as defined by Putnam, were not an equivalence relation, then the ontology of time would be relative.

Actually, questioning Putnam’s assumption that R is an equivalence relation is one of the main strategies for questioning Putnam’s whole argumentation. In this paper, I will focus on this strategy and attempt to show that questioning the equivalency of R amounts to a commitment to a notion of relative ontology, and this notion, I will try to show, is untenable.

Some Remarks On Minkowski Spacetime

In this section, I will give, very briefly, some essential notions from the Special Theory of Relativity, notions which are needed for further discussions of this paper, namely, Lorentz Transformations, the Spacetime interval (Proper Time) and Minkowski diagram.

Putnam’s Argument

This section devotes to explaining the argument that Putnam offered in favor of the Static Model of Reality. He starts with introducing a relation, R, which connects two events with respect to their reality:

If it is the case that all and only the things that stand in a certain relation R to me-now are real, and you-now are also real, then it is also, the case that all and only the things that stand in the relation R to you-now are real. (Putnam, 1967: 242)

So if R(X, Y) is the case, then Y is real for (or as of) X. The important thing here is that this assumption implies that R must be an equivalence relation. For, let the set O be the set of all real events. And let assume that X is a real event and let define the relation R such that all and only the events that stand in relation R to X are real, then:

O = OX = {Y| R(X, Y)}

Now if for every Y ϵ OX, OX = OY, then R is an equivalence relation and no real event is privileged in defining O. (This is what Putnam calls the principle of no privileged observer)

He goes on to link R with simultaneity. He links a claim about simultaneity to a claim about reality with the assumption that: (SIM is the simultaneity relation)

If SIM(X, Y) then R(X, Y)

He doesn’t consider the other way (if R(X, Y) then SIM(X, Y)) because the Special Relativity has taught us that the SIM is a non-transitive relation. So, what he uses from the Special Relativity is that the SIM is a non-transitive relation.

His final step is to show that, since simultaneity is a non-transitive relation and R is equivalence, then every event in Minkowski spacetime is in the relation R to every other event, and, so, the reality of one event entails the reality of every other event in spacetime.

Attempts to Make the Dynamic Model Compatible with the Special Relativity

One way of criticizing Putnam’s argument consists of questioning the equivalency of R. In these two sections, I will discuss Dynamic Models presented assuming either the non-transitive R (Sklar 1981 & 1977, Hinchliff 1996) or, particularly, the non-symmetric R (Stein 1968 & 1991). Then I explained extensively how these options inevitably involve a radical shift from the traditional notion of either ‘reality’ in one case (non-transitive R) or ‘the present’ in another (non-symmetric R). The concepts of the reality and the present would lose their universality and so would lose their ‘traditional’ sense.

Relativity of Reality

In this section, I will try to show that why assuming a non-equivalence R will result in the relativity of reality. As we saw, using the relation R, the ontology set, relative to X, has been defined as follow, assuming the reality of X:

OX= {Y| R(X, Y)} = {X, Y, Z, P, Q …}

Now, by privileging every member of OX we can define an ontology set relative to that member: OX, OY, OZ… But if R is an equivalence relation, then each of these sets would consist of the same events:

OX=OY=OZ=OP=…

So, the equivalency of R entails the absoluteness of the ontology set. And, similarly, the non-equivalency of R entails the relativity of the ontology set..

Why the Relativity of Reality Is Untenable

In this section, I will discuss in details why assuming a non-equivalence R, and hence, the relativity of reality is untenable. I will give two main reasons which can be outlined as follow:

1-    Assuming that R can be non-equivalence is unwarranted. It has justification neither in physics nor in metaphysics. This is because the assumption that R can be non-equivalence would make the ontology set relative and hence the reality will be relative. A given event Y can be real as of X, but unreal as of Z. Relativizing the reality not only is unintuitive but would result in a completely different dynamic model in which the present and the ontology is not absolute. So, defending a non-equivalence R is not amount to saving the traditional dynamic model and has no justification, given the availability of the Static Model.

2- This move is in some sense inconsistent. For, as we saw in section 6, to define an ontology set relative to a given event, X, that event is supposed to be real. However, because of the relativity of reality, the proposition “X is real” does not has a truth condition. So, the very set of relative ontology cannot be defined.

   References

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Keywords

• Dynamic model of reality
• Becoming
• Minkowski Spacetime
• Special Theory of Relativity
• Relative reality