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#211 Tenseless Time and Identity over Time

May 02, 2011

Does a "tenseless" theory of time violate the Principle of Identity?

Hi Dr. Craig, I'm from Brazil. I watched your interview with Robert Lawrence Kuhn (host of PBS' "Closer to Truth"), in which you distinguished two philosophical views of time. The first one is the tensed view of time.

But I have wondered deeply about the tenseless one. In this view, the past, the present and the future are equally real and the observed "tenseness” of time is just an illusion of our minds.

Here is the problem: if the positions (a) and (b) of an observed electron (x) are simultaneously real, then the statement "electron (x) is electron (x)" would be false, which means that the principle of identity would be false too. Is that right?

The tenseless model has some other absurd implications:
- If all the states of my mind are simultaneously real, why in the world do I have this dynamic illusion?
- Am I already dead but not aware of it?
Moreover, I think that it entails that the nature of our minds isn't material.

If this model of time is in deed so absurd, why do Stephen Hawking embraces it despite all the odds? Is modern science that much incompatible with our awareness of the world? Or is Hawking doing just the same mistake as Einstein did regarding the expansion of space just to avoid the beginning of the Cosmos?

I'm not an english native writer, but I did my best.

God bless you Dr Craig

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Photo of Dr. Craig.

Dr. craig’s response


I’m so encouraged by the number of astute Christians in Brazil whom we are encountering through Reasonable Faith. As Brazil emerges to superpower status during this century and as the Christian church there continues to burgeon, it gives grounds for great optimism about the future.

Your perceptive question, Daniel, is one which I’ve addressed in my essay “McTaggart’s Paradox and the Problem of Temporary Intrinsics,” Analysis 58 (1998): 122-127. For those who are unfamiliar with the background of Daniel’s question, let me explain that, broadly speaking, there are two competing views of the nature of time: the tensed view, which holds that temporal becoming is a real, objective feature of the world, and the tenseless view, which holds that all moments of time, whether past, present, or future, are equally real and existent, so that temporal becoming is an illusion of human consciousness. Philosophers are deeply divided as to which view is correct.

Now what Daniel has noticed is that the tenseless view has a very strange implication. Consider some entity x that exists at two different moments of time. Rather than an electron, let x be you yourself, to sharpen the paradox. It follows from the Principle of the Indiscernibility of Identicals that you are not the same person who existed just one minute ago! For on the tenseless theory of time, these are two distinct objects occupying different locations in spacetime. Moreover, they have different properties: the later person may have a slightly different shape or a few less molecules. So they cannot be identical, since they have discernible properties.

What this implies is not that the tenseless time theorist must abandon the principle of identity, since that is a necessary truth of logic, but rather that the tenseless time theorist must hold that intrinsic change is impossible and that nothing actually endures through time! These consequences are generally acknowledged by tenseless time theorists. They hold that what we call persons are just three-dimensional slices of four-dimensional spacetime “worms”. The various slices are different objects, just as the different slices of a loaf of bread are. One slice does not turn into another, nor does any undergo intrinsic change. The appearance of change arises because the various temporal slices have different intrinsic properties. There is no more intrinsic change in objects over time than in a loaf of bread which tapers from large slices at one end to small slices at the other.

I agree with you, Daniel, that this seems really crazy. I have every reason to believe that there is at least one thing which endures through intrinsic change, namely, I myself. I existed a second ago, and despite the changes which have taken place in me, I still exist now. No sane person really believes that he is not the same person who existed a minute ago. Moreover, the tenseless view is incompatible with moral responsibility, praise, and blame. The non-conscious, four-dimensional object of which I am a part cannot be regarded as a moral agent and is therefore not morally responsible for anything. One might say that the spatio-temporal slices or parts of such objects are moral agents. But then it becomes impossible to hold one slice responsible for what another slice has done. How can one person be blamed and punished for what an entirely distinct, different person did? Why should I be punished for his crimes? By the same token, how can moral praise be given to a person for what some other, no longer existent person did? Why should I, who have done nothing, get the credit for the heroism of some other person?

This argument has serious theological ramifications, for Christian theism affirms not only that people are responsible moral agents but also that God is just in holding them responsible for their deeds.

Your second objection about the explanation of the illusion of temporal becoming is also a pressing problem. On the tenseless view mental events themselves are strung out in a tenseless series just as physical events are and are all equally real. My now-awareness of tomorrow is just as real as my now-awareness of today. The experience of the successive becoming of experiences is illusory. Experiences do not really come to be and pass away. But that flies in the face of the phenomenology of time consciousness. It denies that we experience the becoming of our experiences. For if we do have such an experience, then we must ask all over again whether that experience is mind-dependent or not, and so on. To halt a vicious infinite regress, the tenseless time theorist must deny that we do experience the becoming of experiences. But such a phenomenology is obviously inaccurate.

I’m not sure why you say that the tenseless view implies materialism with respect to human beings; but tenseless time theorists are for the most part wedded to naturalistic epistemology and so would in any case be ill-disposed to any mind-body dualism.

So why does someone like Stephen Hawking espouse a tenseless view of time? I think that the main reason is that physics finds it useful to treat time and space as a four-dimensional entity called spacetime in which temporal becoming plays no part. Relativity Theory in particular becomes perspicuous in such a context. Unfortunately, far too many physicists, having never studied philosophy, naively take this geometrical representation as a piece of metaphysics rather than as a merely heuristic device. One therefore has to be very cautious about the statements of physicists when it comes to the nature of time.

- William Lane Craig