Philosophy Cambridge Mellor Time Tense

Articles by |
Books written by |
edited by |
D. H. Mellor

This is the text of my comments at the Joint Session Symposium on
Transcendental Tense on 11 July 1998.
The page references to Mr Lucas's
'Transcendental Tense II' are to the printed version in the
Aristotelian Society Supplementary Volume 72 (1998), 45-56.

Transcendental Tense: Reply to Mr Lucas

© D. H. Mellor 1998

Kant says in his Critique of Pure Reason that our knowledge
of time, for example of when events occur, is transcendental.
(By 'events' here I mean all objects, other than times, which are
located in time.) Part of what he means by calling this knowledge
'transcendental' is that the times we know events occur at are not
objects. Our knowledge of these times is just a way - a
temporal way - of knowing about objects which are not times:
a way of knowing however that we couldn't do without, and that we
must be able to acquire a priori, i.e. without deriving it
from experience, since we must already have it in order to have any
experience at all.

I argue in my paper that while these claims of Kant's are false
of times, they are true of tenses, by which I mean
locations in McTaggart's A series: not just past, present and
future, but also more restricted locations like yesterday, today and
tomorrow. Thus where Kant says that the world contains no times, read
either as Newton's absolute times or as Leibniz's temporal relations
between events, I say it contains no tenses, read either as temporal
regions or as properties of events. I say therefore that our
knowledge that this event occurs today is not knowledge of
today as an object in Kant's sense. Tensed knowledge is just a
way - a tensed way - of knowing about events and other objects,
including dates like 11 July 1998, which are not tensed: a way
of knowing however that as agents we cannot do without, and that I
argue we may well be able to acquire a priori, i.e. without
deriving it from the content of any experience.

I derive these Kant-like claims about tense from a tenseless
theory of time, which I think explains them better than Kant's own
distinction between merely empirically real tensed phenomena
and really real - and tenseless - but otherwise unknowable
noumena. This tenseless theory of time I only sketch in my paper in
enough detail to show how to derive my claims about tense. Apart from
that I don't argue for it, since I've done that elsewhere, and all I
wanted to do here was to show what good sense it makes of what Mr
Lucas calls 'some of Kant's dark sayings, suitably reinterpreted'.

Now, however, since what Mr Lucas challenges is not so much my
derivation of these claims about tense as the tenseless theory I
derive them from, I need to defend that theory against his attacks. I
haven't of course time to give the full case for the theory, which in
any case is now available again in a much improved form in
the elegant and modestly-priced little volume called Real Time
II. So here I shall simply reply briefly to the points Mr Lucas
makes against it.

First, he shows how Kant's First Antinomy can be answered within a
tensed view of time. As I said in my paper, I don't dispute that. I
really only discussed that antinomy because Kant's arguments for it
make clear his unargued assumption of a tensed view of time, which I
suspect is what made his insights about tense generate what Mr
Lucas rightly labels his 'projectivist' view of time itself.

However, that speculation about Kant's thought processes is
neither here nor there, since my paper is not really about Kant but
about the status of tense. My main reason for referring to Kant was
simply to show how a tenseless theory can extract important truths
about tense from Kant's otherwise incredible theory of time.

So the parts of Mr Lucas's reply that I really need to answer are
his attacks on my tenseless view of time. Some of these attacks,
however, seem to me rather wide of the mark. It is for example a bit
rich to accuse me (on p.48) of arguing that 'tensed language is
inherently self-contradictory' when, on the contrary, I say in
tenseless terms precisely what makes tensed statements like 'The 1998
Joint Session is on now' true. Of course being tensed doesn't
make that or any other object-language statement self-contradictory,
and I never said it did: my theory of tensed language is not an
error theory. All I've said, following McTaggart, is that
trying to give tensed truths tensed truthmakers generates
contradictions, which is quite another matter.

To see the difference, take for example true statements about
nobody, like 'Nobody is smaller than a flea' or 'Nobody is
larger than a galaxy'. There is no contradiction in those two
statements. But there would be a contradiction in taking them
to be made true by some entity called 'Nobody' having the
incompatible properties of being smaller than a flea and larger than
a galaxy. That's the analogue of my view of tense. There need
be no contradiction in our tensed language, only in the view that it
has tensed truthmakers.

I also take some exception to being accused (on p.49) of holding
that 'truth-conditions [are] all-important and meaning of no
significance'. That, for a start, is an obviously false contrast,
since one thing that makes a contingently true sentence's truth
conditions important is the way they determine or at least constrain
its meaning. And far from taking meanings to be insignificant, I take
my theory to be strongly supported by the fact that the way in which
the tenseless truth conditions of contingent tensed sentences vary
with time gives such a good explanation, not only of how these
sentences differ in meaning from each other - and of course
from all tenseless sentences - but also of why we cannot do
without sentences and thoughts with these temporally variable
tenseless truth conditions.

I was even more startled to read (also on p.49) that I thought
philosophers didn't need 'to know what o'clock it was, and whether it
was time to give a lecture ...'. No such luck. Of course we need to
know such things, and therefore to think and speak very often in
irreducibly tensed terms. But this does not stop us also making true
statements that are tenseless or in other ways non-indexical. Nor in
particular does it stop us using non-indexical statements to say what
the varying truth conditions, and hence the meanings, of tensed and
other indexical statements are.

So of course, as Mr Lucas says (on p.49), 'language needs to
conjugate over tenses as ... over the first- and second-persons'. But
this doesn't mean that reality must be tensed, any more than
the existence of truths about nobody requires reality to contain
that impossible entity. On the contrary, I believe, it is only
a tenseless view which, while denying that reality is tensed,
exploits the underrated fact that all our thoughts, statements and
actions also occur in tenseless time, that can explain why we
do need to think and speak in tensed ways.

Let me turn now from these mere misunderstandings to issues on
which Mr Lucas understands me perfectly but disagrees. The first
issue is this. I say we need to understand what 'later' means in
order to understand tensed terms like 'tomorrow' - meaning the day
that is one day later than today - whereas Mr Lucas thinks it's the
other way round.

I admit of course (indeed I insist) that we have an innate
capacity for tensed thought, just as we have for its spatial and
personal analogues: that is, for thoughts about what's here,
and at various distances in various directions from here, and about
me and you - the people I am speaking to - and other
people characterised by their being related to me in various ways. In
short, and in general, we have an innate capacity for indexical
thought of all these three kinds - temporal, spatial and personal -
all of them equally indispensable and equally irreducible to their
non-indexical counterparts.

I argue moreover that every indexical belief of these three kinds
relies on the same basic causal mechanism - simple contiguity of
cause and effect - to get the time, the place and the thinker of
that belief into its truth condition. But then what, I ask, makes a
tensed belief temporally rather than spatially or personally
indexical? I say it is the fact that having this belief
disposes me to acquire non-indexical beliefs which are
temporal rather than spatial or personal. So, for example,
what makes my present-tensed belief that I'm speaking now a
temporal belief is that it disposes me to believe, of any
tenseless time t that I take to be present, that I am speaking
at t.

If this is right, then our capacity for tensed belief requires us
to be able to distinguish times from places and people, and hence to
distinguish the different relations which differentiate entities of
those three kinds. In other words, we must have a 'later than'
concept which differs from any of its spatial or personal analogues.
And how we could get such a concept, if not by learning to recognise
perceptible instances of it, I confess I have no idea. Which brings
me to my basic point of disagreement with Mr Lucas on this matter.

He says (on p.50) that, to him,

some things look future: I duck and blink and flinch
as I perceive the approaching danger, and sigh with relief when the
dentist at last lays down his drill.

Well, far be it from me to cast doubt on these autobiographical
fragments, except to say that they do not show that anything
looks future, or past, or present. Of course, given the speed of
light, we have, for obvious evolutionary reasons, developed the
default habit of letting what we see cause us to believe that it's
happening now - a present-tense belief which then causes us
to have related future- and past-tense beliefs, which in turn cause
actions and reactions like Mr Lucas's ducking and sighing.

I don't deny that. What I do deny is that what we
see ever looks past, present or future in any sense that
would, for example, enable us to refute a fortune-teller's claims to
be seeing the future in her crystal ball by pointing out that what
she is seeing looks past or present rather than future. We can do no
such thing, of course, because in that sense nothing looks
tensed at all.

And that is the sense that matters here, since that is what
shows that we could not have got our concepts of tense by
learning to recognise instances of pastness, presentness or futurity
that are perceptible as such, since there are no such instances.
Whereas the later than relation, on the other hand, has
millions of perceptible instances, among them every
perceptible instance of a change going one way rather than another -
like my hand moving from right to left rather than left to right -
including, as I say in my paper, all the self-intimating changes in
our own experiences. Those are the instances that we learn to
recognise, thereby acquiring a 'later than' concept and hence, given
our innate capacity for indexical thought generally, our capacity for
tensed thought in particular.

The second major issue that Mr Lucas and I disagree about is
whether I can explain why time is, as he puts it (on p.50),

that pervasive condition of all experience and activity in which I
formulate intentions about what I shall do in the future, carry
them out in the present and remember them in the past.

He says I can't explain all that; but I can. I do it with causal
theories of the difference between time and space, and of how our
cumulative memories of our experiences tell us the order - the time
order - in which we have those experiences. That is how I show that
if tenseless time is, as I argue, the causal dimension of
spacetime, it must also be Mr Lucas's 'pervasive condition of all
experience' or, as Kant calls it, 'the form of inner sense'.

Yet even if I were wrong about all that, it would still not
follow, as Mr Lucas claims (again on p.50), that for us tenseless
chaps the non-spatial dimension of what we call 'spacetime' might as
well be temperature. That's nonsense. What makes spacetime a
four-dimensional manifold is the simple fact that objects in space
and time can be in contact - and hence capable of immediate
interaction - if and only if they share determinate values of
four independent linear determinables: three spatial and one
other. That other, by definition, is time. It can't be temperature
(or any other linear determinable), simply because two objects being
in the same place and at the same temperature is neither necessary
nor sufficient for them to be in contact. You can't contact Napoleon
now by going to Elba and sharing his temperature: it's not his
temperature but his time there that you would need to share to meet
him. And that obvious fact is quite enough to show, on any view of
time, that whatever time is, it isn't temperature.

Our last major disagreement is over the implications of modern
physics for a tensed view of time. The special theory of relativity
makes simultaneity and hence temporal presence at a distance relative
to a so-called reference frame. I and others have argued that the
lack of a single preferred reference frame in special relativity
counts against any view of time which makes existence depend on
temporal presence, that is, views such as the tensed views that only
the present, or only the past and present, exist. There is of course
no problem in taking the earthly dates of events ten light
years away on Sirius to vary with reference frames when there's
nothing to choose between those frames. But no one can seriously take
the existence of remote objects to vary in this way. It's bad
enough to say, as many tensed theorists do, that even on earth the
truth value of the tenseless statement that Einstein exists
depends on when it is made; to add that over a twenty year period on
Sirius, its truth value would also depend on a factually undetermined
choice of reference frame should strain the credulity even of a
tensed theorist.

This is why Mr Lucas claims (on p.54), that today 'most
cosmologists use a version of the General Theory [of relativity] with
boundary conditions that determine a universe-wide world time'. I
think he is wrong about this. Far from modern cosmology supporting
the idea of a uniquely privileged reference frame which determines an
absolute universe-wide simultaneity relation, I am assured (by no
less an authority than the Astronomer Royall ...) that it positively
implies that there is no such thing.

The point, as I understand it, is this. Modern cosmology takes the
universe to be expanding uniformly in all directions from every point
in it. In other words, wherever we are, every distant galaxy, or
cluster of galaxies, is receding from us at a rate proportional to
its distance from us, the constant of proportionality being Hubble's
constant, which is about 37 kilometres per second for every million
light years.

This fact lets us define at every point a local rest frame,
i.e. what it is to be at rest, at that point. This is the frame in
which, in all directions, all galaxies at any given distance are
receding at the same rate, thus giving Hubble's constant the same
value in all directions. This is the frame relative to which we can
say absolutely that the earth, or the solar system, is moving through
space at such-and-such a speed in such-and-such a direction.

But now consider a galaxy a million light years away which in this
sense is at rest, i.e. is at rest in its local rest frame. But of
course in our rest frame this galaxy is not at rest:
it's moving away from us at 37 kilometres per second. So its rest
frame is, to put it mildly, not the same as ours. In short, although
everywhere in the universe has a local rest frame, and hence a
locally privileged simultaneity relation, these frames are all
different, and so therefore are the simultaneity relations they
define. And as modern cosmology assumes that there is no privileged
point, no centre of the universe - any more than there is a centre
to the surface of the earth - this means that there is no privileged
rest frame or simultaneity relation. And this means that modern
cosmology does not, as Mr Lucas implies, counter the argument
against tensed theories which I and others have derived from special
relativity. On the contrary, it reinforces it.

Where, finally, does this leave Schrödinger's cat? I agree
with Mr Lucas that this moggie should, as Oscar Wilde's Lady
Bracknell said of her nephew's imaginary invalid friend Bunbury,
'make up his mind whether to live or to die: this
[quantum-mechanical] shilly-shallying with the question is absurd!'
But whatever the cat or its owner does, and however we interpret
quantum theory, I see no contradiction with what I have just said
about modern cosmology.

Of course there can be a first point in the cat's world line at
which, as a matter of fact, it is definitely dead, or definitely
alive, and no longer in a mere superposition of those two states.
That possibility does not require this point to be absolutely
simultaneous with any point on the world line of a cat, or anything
else on Sirius, or in any other remote part of the universe. And even
if it did require that, this would not show that feline
wave-functions can only collapse if time is tensed.

In short, and in conclusion, I deny that modern physics gives us
any more reason to reject a tenseless view of time than do Mr Lucas's
closing claims (on p.55), where he says that

Tenseless discourse leaves out too much. It is difficult to see -
he continues - how I could acquire a specifically temporal sense
of temporal order without a tensed understanding of time, any more
than I could acquire a full sense of personality without some
first-personal experience and agency.

I agree with all that. The difference between us is that my
tenseless theory of time can explain all that and Mr Lucas's tensed
theory can't - except in the trivial sense of entailment in which an
inconsistent theory can explain anything. But apart from that, our
obvious, and obviously fundamental, ability and need to think and
speak in irreducibly tensed ways, which I can explain as a theorem,
Mr Lucas can only take to be an inexplicable axiom. That, it seems to
me, is not a virtue of his tensed theory of time but a serious
defect.

Updated 11 September 2019