B-theory of time

From Wikipedia, the free encyclopedia
  (Redirected from B-Theory of time)
Jump to: navigation, search

The B-theory of time is a metaphysical philosophy of time. The theory is often drawn upon in theoretical physics[1], and theories such as four-dimensionalism and eternalism also draw upon B-theory.


B-theory originates from the metaphysical A-theory and B-theory's of time. The two theories were originally derived from the analysis of time and change developed by Cambridge philosopher J. M. E. McTaggart in 'The Unreality of Time' (1908), in which events are ordered via a tensed A-series or a tenseless B-series. A-series is closely related to presentism while B-series is closely related to eternalism.[citation needed] It should be noted that the debate between A-theorists and B-theorists is a continuation of a metaphysical dispute reaching back to the ancient Greek philosophers Heraclitus and Parmenides.

Events (or 'times'), McTaggart observed, may be characterized in two distinct, but related, ways. On the one hand they can be characterized as past, present or future, normally indicated in natural languages such as English by the verbal inflection of tenses or auxiliary adverbial modifiers. Alternatively events may be described as earlier than, simultaneous with, or later than others. Philosophers are divided as to whether the tensed or tenseless mode of expressing temporal fact is fundamental. Those who (like Arthur Prior[2]) take the tensed notions associated with the past, present and future to be the irreducible foundations of temporality and our conceptions of temporal fact, are called A-theorists (similar to presentists). A-theorists deny that past, present and future are equally real, and maintain that the future is not fixed and determinate like the past. A-theorists also believe that a satisfactory account of time must acknowledge a fundamental metaphysical difference between past, present and future (Prior 2003). Those who wish to eliminate all talk of past, present and future in favour of a tenseless ordering of events are called B-theorists. B-theorists (such as D.H. Mellor[3] and J.J.C. Smart[4]) believe that the past, the present, and the future are equally real. Speaking generally, the difference between A-theorists and B-theorists is often described as a dispute about temporal passage or 'becoming' and 'progressing'. B-theorists argue that this notion is purely psychological and not epistemological, and embodies serious confusion about time, while many A-theorists argue that in rejecting temporal 'becoming', B-theorists reject time's most vital and distinctive characteristic.[citation needed] It is therefore common (though not universal) to identify A-theorists' views with belief in temporal passage.

Description of B-theory[edit]

B-theory in metaphysics[edit]

In (Mellor 1998), Mellor states "The past, the present, and the future feature very differently in deliberation and reflection. We remember the past and anticipate the future, for example, but not vice versa. B-theorists maintain that the fact that we know much less about the future simply reflects an epistemological difference between the future and the past: the future is no less real than the past; we just know less about it."

B-theory in theoretical physics[edit]

The B-theory of time has also received a lot of support from the physics community.[5][6] This may be due to it's compatibility with physics and that many theories (such as special relativity and theories regarding extra dimensions) point to a theory of time, similar to B-thoery.[7] For example, in special relativity, the relativity of simultaneity implies there is not a unique present, and many of special relativity's counter-intuitive predictions such as length contraction and time dilation are a result of this. Relativity of simultaneity implies eternalism (a block universe) and hence a B-theory of time, where the present for different observers is a time slice of the four dimensional universe. Thus it is also common (though not universal) for B-theorists to be four-dimensionalists, that is, to believe that objects are extended in time as well as in space and therefore have temporal as well as spatial parts. This is sometimes called a time-slice ontology (Clark, 1978).


It is noted by Dean Zimmerman in 'Presentism and the Space-Time Manifold' that A-theory is 'almost certainly a minority view among philosophers', while B-theory has 'achieved broad acceptance'.[8] Though in the minority, philosophers that support A-theory over B-theory include Ian Hinckfuss, J. R. Lucas, E. J. Lowe, William Lane Craig and more.

William Lane Craig is a vocal supporter of A-theory (and hence opposes B-theory), however Craig has been criticised and accused by both sides of 'pushing' A-theory (and opposing B-theory), because it coincides with his religious beliefs. Craig has argued that "temporal becoming is an entirely subjective phenomenon, and hence not an objective feature of reality. Therefore if the mental phenomenon of temporal becoming is an objective feature of reality, this amounts to a denial of the B-theory of time". [9]

Examples in fiction[edit]

The idea behind a B-theory of time and consequently four-dimensionalism and eternalism, are demonstrated in the film Interstellar. The physics of Interstellar was based on the work of renowned physicist Kip Thorne.[10] Astronaut Cooper is sent to a region of space called a 'tesseract', built by beings of 5-dimesnions. In the tesseract, Cooper is able to perceive all of time simultaneously, and is consequently able to transmit information back to a time in his perceived past. According to the B-theory of time, this is consistent and does not induce a paradox.


  1. ^ https://www.youtube.com/watch?v=H1WfFkp4puw
  2. ^ (French) http://hylo.loria.fr/content/papers/files/tense.pdf
  3. ^ "Philosophy Cambridge Mellor Time Tense". People.pwf.cam.ac.uk. Retrieved 2014-03-03. 
  4. ^ "Google Drive Viewer". Docs.google.com. Retrieved 2014-03-03. 
  5. ^ https://www.youtube.com/watch?v=f9AiPuIsqck/
  6. ^ https://www.youtube.com/watch?v=H1WfFkp4puw
  7. ^ https://www.youtube.com/watch?v=R1cexcjdyIE
  8. ^ http://fas-philosophy.rutgers.edu/zimmerman/Presentism%20and%20Rel.for.Web.2.pdf
  9. ^ Craig, William Lane (2000). The tenseless theory of time : a critical examination. Dordrecht [u.a.]: Kluwer Acad. Publ. ISBN 978-0792366355. 
  10. ^ "New 'Interstellar' Trailer Goes Deep; Plus Kip Thorne Featurette". /Film. October 1, 2014. Retrieved October 5, 2014. 


  • Clark, M. (1978) 'Time-slices of particular continuants as basic individuals: An impossible ontology'. Philosophical Studies 33, 403–408.
  • Davies, Paul (1980) Other Worlds. Harmondsworth: Penguin.
  • McTaggart, J.M.E. (1908) 'The Unreality of Time', Mind 17: 457-73.
  • McTaggart, J.M.E. (1927) The Nature of Existence, Vol II. Cambridge: Cambridge University Press.
  • Mellor, D.H. (1998) Real Time II. London: Routledge.
  • Prior, A.N. (2003) Papers on Time and Tense. New Edition by Per Hasle, Peter Øhrstrøm, Torben Braüner & Jack Copeland. Oxford: Clarendon.
  • Putnam, H. (2005) 'A Philosopher Looks at Quantum Mechanics Again', British Journal for the Philosophy of Science, 56, pp 615 – 634.
  • Quine, W. V. O. (1960) Word and Object, Cambridge, MA: M.I.T. Press.

External links[edit]

  • Markosian, Ned, 2002, "Time", Stanford Encyclopedia of Philosophy
  • Arthur Prior, Stanford Encyclopedia of Philosophy