Temporal Paradoxes: A Critique of Lewis's Solution to the Grandfather Paradox

Abstract

This essay critically examines David Lewis's proposed solution to the Grandfather Paradox and argues that it fails to provide a coherent account of time and causality. Lewis’s approach hinges on the ambiguity of the word 'can,' which he claims is context-dependent and relative to different possible worlds. By accepting that Tim both can and cannot kill his grandfather, Lewis attempts to resolve the paradox, but this leads to a contradiction that undermines the logical consistency necessary for a robust theory of time travel. The essay counters Lewis’s view by drawing on the arguments of Garrett and Vihvelin. Garrett critiques Lewis's reasoning, pointing out that the impossibility of changing the past does not equate to Tim’s inability to kill his grandfather; rather, it simply means that Tim will not kill him. This distinction is crucial for understanding the limits of time travel without falling into logical inconsistencies. Vihvelin further challenges Lewis by emphasizing that Tim’s inability to kill his grandfather is not a matter of context or possibility but a consequence of the deterministic nature of temporal events. The essay also explores McTaggart's distinction between the A-series and B-series of time to reinforce the argument against Lewis. By examining the B-series, which treats time as a series of fixed events rather than a flowing present, the essay illustrates a more stable and coherent framework for understanding time travel. This perspective discredits Lewis’s reliance on possible worlds by showing that it does not resolve the fundamental issues posed by the Grandfather Paradox. In conclusion, the essay argues that Lewis’s solution is ultimately flawed because it fails to address the core temporal and causal issues of the paradox. In contrast, the arguments presented by Garrett and Vihvelin offer a more consistent and logically sound approach, leading to a more coherent understanding of time and its implications for time travel.