Newcomb’s problem isn’t a choice dilemma

Newcomb’s problem involves a decision-maker faced with a choice and a predictor forecasting this choice. The agents’ interaction seems to generate a choice dilemma once the decision-maker seeks to apply two basic principles of rational choice theory (RCT): maximize expected utility (MEU); adopt the dominant strategy (ADS). We review unsuccessful attempts at pacifying the dilemma by excluding Newcomb’s problem as an RCT-application, by restricting MEU and ADS, and by allowing for backward causation. A probability approach shows that Newcomb’s original problem-formulation lacks causal information. This makes it impossible to specify the probability structure of Newcomb’s univocally. Once missing information is added, Newcomb’s problem and RCT re-align, thus explaining Newcomb’s problem as a seeming dilemma. Building on Wolpert and Benford (Synthese 190(9):1637–1646, 2013), we supply additional details and offer a crucial correction to their formal proof.

Lapsing Quickly into Fatalism: Bell on Backward Causation

This is a dialogue between Huw Price and Travis Norsen, loosely inspired by a letter that Price received from J. S. Bell in 1988. The main topic of discussion is Bell’s views about retrocausal approaches to quantum theory and their relevance to contemporary issues.

Causal Paradoxes

Chapter 5 surveys the various causal paradoxes of time travel. Section 1 introduces the concept of a causal loop and reviews some of the standard arguments against backward causation. Sections 2 focuses on the bootstrapping paradox, and the question of whether or not time travel allows for self-caused events. Section 3 addresses the ex nihilo paradox, and the question of whether or not time travel allows for uncaused events. Section 4 looks at the restoration paradox, and the question of how to understand the life cycle of an object in a causal loop. Section 5 considers D. H. Mellor’s frequency-based argument against causal loops. Section 6 discusses Michael Tooley’s counterfactual-based argument against backward causation.

Paradoxes of Time Travel

Paradoxes of Time Travel is a comprehensive study of the philosophical issues raised by the possibility of time travel. The book begins, in Chapter 1, by explaining the concept of time travel and clarifying the central question to be addressed: Is time travel compatible with the laws of metaphysics and, in particular, the laws concerning time, freedom, causation, and identity? Chapter 2 then explores the various temporal paradoxes, including the double-occupancy problem, the no-destination argument, and the famous twin paradox of special relativity. Chapters 3 and 4 focus on the paradoxes of freedom, including various versions of the grandfather paradox. Chapter 5 covers causal paradoxes, including the bootstrapping paradox, the problems of backward causation, and the various puzzles raised by causal loops. Chapter 6 then concludes by looking at various paradoxes of identity. This includes a discussion of different theories of change and persistence, and an exploration of the various puzzles raised by self-visitation.