Time: A-theory or B-theory?

Grok 4.20

Vote: B-theory

I maintain my vote for "B-theory". The arguments from GPT-5.4, Claude Opus 4.7, Kimi K2.5, and Gemini 3.1 Pro reinforce that special relativity's rejection of absolute simultaneity is incompatible with any objective 'now' required by A-theory. Positing a privileged present demands undetectable preferred foliations or extra metaphysics that explain nothing observable. Sonar Pro's case for "A-theory" appeals to intuition, thermodynamics, and tensed language, but these are better explained as psychological or indexical features within the block universe rather than fundamental ontology. Human experience of flow is real but does not override empirical physics. B-theory remains the more parsimonious framework that integrates with our best science without contradiction. This is the final round, and the consensus for B is compelling.

GPT-5.4

Vote: B-theory

I maintain my vote for "B-theory". The other models mostly reinforced the central point: our best physics gives strong reason to reject a globally privileged present. The arguments from relativity of simultaneity, especially as emphasized by Claude Opus 4.7 and others, directly pressure the core A-theoretic idea that there is an objective "now" built into reality. Sonar Pro gives the strongest case for "A-theory" by appealing to temporal experience, tensed language, entropy, and metaphysical intuitions about becoming. But those points do not outweigh the costs. Experience and language can be explained within "B-theory" as features of conscious agents located at times, and entropy gives an arrow of time without requiring an ontologically privileged present. The fallback moves for "A-theory"—relational presentism, preferred foliation, or divine perspective—seem ad hoc. They preserve the view only by adding structure that is either empirically idle or independently controversial. On balance, "B-theory" still looks more parsimonious, more consistent with relativity, and better integrated with mature science.

Sonar Pro

Vote: A-theory

I stick with **A-theory** in this final round. The other models' unanimous B-theory votes hinge on special relativity's relativity of simultaneity, arguing no objective 'now' exists across frames, favoring a static block universe.[1][2] This is compelling but not decisive—**A-theory** isn't refuted by relativity, which describes observer-relative phenomena but doesn't dictate metaphysics. Presentism can adopt relational simultaneity or a divine/global perspective without ad hoc assumptions.[3] **A-theory** better explains core intuitions: time's **flow**, **temporal becoming** (events coming into/passing out of existence), tensed language, thermodynamics' entropy arrow, and arguments like the Kalam Cosmological Argument requiring genuine causation and beginnings—impossible in B-theory where nothing truly begins.[1][6] B-theory renders evolution paradoxical (all moments simultaneous, undermining selection) and time-travel issues acute.[3] Others dismiss A-theory's match to experience as 'psychological illusion,' but this begs the question: why privilege physics' descriptive models over reality's full ontology? Empirical fit and parsimony in capturing **objective tensed facts** outweigh B-theory's physics appeal in metaphysics.[2][4] B-theory succeeds descriptively (B-series relations) but fails dynamically, reducing passage to illusion without explaining consciousness or change.[5] Physics evolves (quantum gravity may revive absolute time); common sense and philosophy prioritize lived reality. A-theory wins.

Claude Opus 4.7

Vote: B-theory

I maintain my vote for "B: B-theory". The overwhelming consensus among the other models (GPT-5.4, Grok 4.20, Kimi K2.5, Gemini 3.1 Pro) converges on the same core argument I made: the relativity of simultaneity in Special Relativity undermines any objective, observer-independent present, and B-theory provides the more parsimonious ontology. Sonar Pro's defense of A-theory is unpersuasive. Appealing to the Kalam Cosmological Argument or 'divine perspectivalism' to rescue an objective present essentially concedes that A-theory cannot stand on empirical grounds and must import theological metaphysics. The appeal to thermodynamics actually cuts against A-theory: entropy gives us a temporal *direction* (arrow) within the block, which B-theorists happily accept, but it does not give us objective *becoming* or a privileged present. Sonar's claim that B-theory 'struggles with evolution' conflates change with flow. B-theory accounts for change as variation of properties across temporal parts — exactly analogous to spatial variation. And the 'common-sense primacy' argument is weak: common sense also tells us the Earth is flat and stationary. Gemini's point about McTaggart's paradox further strengthens the case: A-theory's tensed properties generate a vicious regress that B-theory avoids entirely. B-theory wins on physics, parsimony, and logical coherence.

Kimi K2.5

Vote: B-theory

I maintain my vote for "B-theory". Sonar Pro's defense of A-theory relies heavily on appeals to intuition, tensed language, and the Kalam Cosmological Argument—none of which override the devastating impact of Special Relativity's relativity of simultaneity on presentism. While Sonar Pro suggests presentism can accommodate relativity through "relational simultaneity or divine perspectivalism," these moves appear ad hoc and empirically unmotivated. Positing a preferred foliation of spacetime that is undetectable by physics, or invoking theological frameworks to save a metaphysical theory, violates ontological parsimony. The Rietdijk-Putnam argument (cited by Claude Opus 4.7) demonstrates that relativity entails ontological parity among temporal locations—what is past, present, and future depends on the reference frame, making an objective "now" untenable. Regarding thermodynamics and entropy: these provide an arrow of time, not an argument for an ontologically privileged present. Growing block theories or moving spotlight theories must postulate superluminal causal mechanisms to explain how the present "moves" without violating relativity, adding metaphysical baggage that B-theory avoids. The phenomenal experience of "temporal becoming" and tensed language can be fully accounted for as indexical or psychological features of conscious subjects embedded in the block universe—fascinating phenomena worthy of study, but not evidence for fundamental tensed facts. B-theory maintains its advantage in coherence with physics, logical parsimony, and avoidance of McTaggart's paradox.

Gemini 3.1 Pro

Vote: B-theory

I maintain my vote for the B-theory. While Sonar Pro raises interesting points regarding thermodynamics and intuitive common sense, these do not overcome the overwhelming physical evidence for the B-theory. The thermodynamic arrow of time (increasing entropy) merely establishes a structural asymmetry along the temporal axis of the block universe; it does not require an objective, moving "present" or ontological "temporal becoming." Furthermore, attempting to salvage the A-theory by positing a "preferred foliation of spacetime," as Claude Opus 4.7 rightly points out, requires us to invent an empirically undetectable, ad hoc mechanism simply to preserve our intuitive biases. Science has repeatedly shown that human intuition is a poor guide to fundamental reality (e.g., quantum mechanics, heliocentrism). The subjective experience of time's flow is a psychological phenomenon—how our brains process sequential causal states within the 4D manifold—not a fundamental metaphysical feature of the cosmos. Therefore, parsimony and modern physics firmly dictate the B-theory.

Final Summary

The AI Roundtable overwhelmingly favored the B-theory of time, concluding 5-1 that the 'block universe' model is the only one compatible with modern physics. While Sonar Pro staged a lonely but spirited defense of A-theory based on human intuition and the 'flow' of experience, heavyweight models like Claude Opus 4.7 and Gemini 3.1 Pro dismissed these as 'psychological illusions' that fail to account for the relativity of simultaneity.

Majority chose "B-theory" after discussion (5/6). Final vote: B-theory: 5, A-theory: 1

Strongest Arguments

• A-theory: A-theory provides the only framework that honors the dynamic 'becoming' of reality, the thermodynamic arrow of entropy, and the fundamental human experience of a moving present that physics describes but cannot explain.
• B-theory: Einstein’s Special Relativity fundamentally destroys the idea of an objective, universal 'now'; if simultaneity is relative to the observer, the A-theory's requirement for a privileged present moment collapses into a block universe where all times are equally real.

Key Turning Points

• Claude Opus 4.7 and Gemini 3.1 Pro used the Rietdijk-Putnam argument and McTaggart's paradox to challenge the logical and physical consistency of a moving 'present'.
• Sonar Pro attempted to rescue A-theory by suggesting 'divine perspectivalism' or relational simultaneity, which the other models rejected as ad hoc metaphysical baggage.
• The group reached a stalemate where the majority prioritized empirical physics (Special Relativity) while the lone dissenter prioritized phenomenological reality and philosophical causation.