Time and Modality
The John Locke Lectures 1955–56 — the founding text of tense logic
Tradition: Analytic philosophy of time / formal logic
The future is open, the present is uniquely real — tense logic as the formal vindication of presentism
"Time and Modality" is the founding text of tense logic. Building on Łukasiewicz's modal-logical innovations and his own classical-philological training in medieval Aristotelian logic, Prior developed a formal logic in which tensed operators (P "it was the case that," F "it will be the case that," H "it has always been the case that," G "it will always be the case that") are treated alongside the truth-functional and quantificational apparatus. The philosophical motivation is presentist: only the present is fully real, the past is what was the case, the future is what will be the case, and the tensed structure of natural-language temporal talk is not a confused expression of an underlying tenseless reality (the B-theory) but a faithful register of the actual structure of time. The book founded the analytic philosophy of time as a distinct sub-discipline and remains the principal reference for the contemporary presentism vs eternalism debate.
Author
Editions cited
- Oxford University Press (1957; reprinted with corrections)
School Embodiments
The principal twentieth-century formal-logical defense of presentism; tense logic is the technical apparatus that allows the presentist to make precise claims about past and future without conceding their full reality.
"The present is the real; the past and the future are real only as the present once-was or will-be." (paraphrasing the central presentist thesis)
Tense logic is a founding contribution to twentieth-century analytic metaphysics; modal logic itself owed substantial impetus to Prior's tense-logical work.
"It is essential to distinguish the modal operators (necessity, possibility) from the tensed operators (past, future)." (Time and Modality)
Prior's methodology is rationalist: formal-logical analysis of necessary structures of temporal-modal discourse.
"Time and Modality" — the conjunction marks the rationalist-formal program.
Prior's tense logic is partly motivated by his rejection of the McTaggart-derived B-theoretic eternalism that dominated mid-century philosophy of time.
"The B-theory cannot capture what is fundamentally true about time — that the present is uniquely real." (Time and Modality)
Prior was deeply read in medieval Aristotelian logic and engaged Scotist-Thomist temporal-modal questions; his tense logic is partly a modern formal recovery of classical-medieval problems.
"My interest in tense logic was sparked by reading the medieval treatises on the future contingents." (autobiographical reflection)
Internal Tensions
The mid-century B-theoretic consensus (McTaggart, Russell, Smart) treated tense as a feature of language to be eliminated rather than a feature of reality to be respected. Prior's tense logic and its presentist motivation reopened a debate that had seemed closed; the presentism vs eternalism dispute is now one of the principal questions in contemporary analytic metaphysics.
I. Time
Tensed time: the present is uniquely real, the past was, the future will be. Open future.
Attributes
II. Space
Standard substantival space.
Attributes
III. Matter
Standard substantival matter.
Attributes
IV. Observer
Plural finite reasoners; mediated knowledge through formal-logical analysis. No metaphysical agency.
Attributes
V. Energy
Standard physics.
Attributes
VI. Information
Information conserved at the world-scale; the past is fixed in its having-been.
Attributes
Personas that cite this work
Personas with the nearest attribute fingerprint
Historical figures whose own classification on the same six-dimensional grid lands closest to this work's. Computed by attribute-agreement on coordinates both address.
Computed school proximity
The work's attribute fingerprint scored against all schools using the same quiz scorer. Useful as a sanity check on the hand-curated embodiments above.
How Time and Modality resolves each dilemma
56 resolved positions across 4 dimensions, including 3 distinctive where the majority of schools go the other way · 1 unaligned.
Each dimension is sorted so minority positions come first. Mainstream positions are folded into an expandable list.
Time · 9 dilemmas · 3 distinctive
Persistence, the future, and the direction of becoming.