The passage of time and the evolution of the universe-tree
Creators: name: Reiffer, Randy
Publisher: name: University of British Columbia
Year: 2011

description: McTaggart's paradox leads to the conclusion that time is unreal. The paradox has two key premises: the premise that time flow is a necessary component of time, and the premise that time flow entails a contradiction. The paradox therefore derives its strength from the apparent contradiction entailed by the passage of time. The conclusion of McTaggart's paradox, that time is unreal, could be otherwise stated as the claim that there are no logically possible models of time with both the property of the earlier/later relation and the property of time flow. Given this analysis of the paradox, I claim that McTaggart's conclusion can be rejected. Bigelow (1989) has argued that the logic of McTaggart's paradox suggests a modal solution. One possible modal solution could be along the lines that McCall (1966, 1976, 1984, forthcoming) is developing. I show that McCall's model is a logically and physically possible model of time flow. McCall's model explains the passage of time through the metaphysical mechanism of the evolution of the universe-tree. The universe-tree is a changing set of connections between the physically possible worlds. In the introduction, section 2, I present an overview of the two main groups of philosophical views on the problem of the passage of time. The debate between the two groups, that of tensers and that of non-tensers, serves to illustrate the difficulties that giving an account of the passage of time that must be confronted. The critical difficulty is shown to be to give an account of the changing temporal relation of novness. In section 3, I critically evaluate McTaggart's paradox. In so doing, I clarify the problem of giving an account of the changing temporal relation of nowness. I accept Bigelow's (1989) argument that the logical structure of the paradox, together with the elegance of tense logic, suggests a modal solution to the problem of temporal passage. In the remainder of this section, I show that McTaggart's paradox is logically valid, and that while some of McTaggart's claims are unsound, overall the paradox highlights a crucial philosophical puzzle: to give an account of the ever-changing moving now. In section 4, I show that McCall's model is a logically and physically possible model of time flow. McCall's model objectively distinguishes the present from past and future events through the dynamic evolution of the universe-tree. The tree consists of a branching connectedness relation between the physically possible worlds. The branch-structure is not fixed; the change is asymmetric, and it is this asymmetry that is the ontological extension of the moving now. The asymmetric evolution of the tree makes the branch-structure to be future-directed. The now moves up the tree of connections, actualizing one track as the non-selected branches vanish. I show that McCall's model is logically possible by proving that it is mathematically determinate in its ontological extension. Furthermore, the model is physically possible, since it contains enough topological resources to derive local Euclidean computability. In the final analysis, section 5, I come to the conclusion that McCall's model is a good counterexample to the conclusion of McTaggart's paradox. McCall's model is a logically and physically possible model of time flow. The passage of time is explained by the evolution of the branch structure of the universe-tree. The universe-tree is the set of connections between the selected and nonselected physically possible worlds. The motion of the now in our topological space is the result of the metaphysics of the logical space within which our topological space is embedded. Thus the passage of time in the actual world is a function of the changing relation between the actual world and the other possible worlds.