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July 27, 2006



An interesting paper in this regard: A Psychedelic Neurochemistry of Time.

Pete Mandik

But could a being have the same temporal phenomenology as that of my stream of consciousness, despite undergoing my experience in reverse temporal order, or in assorted jagged bursts?

Hi Dave,

The Australian sci-fi author Greg Egan has a great thought experiment about this in his novel Permutation City in which a computer simulation of a mind is run forward, backward, slow, fast, and out of order all without giving rise to introspectible differences from the point of view of the mind simulated.



Simon Prosser

Hi Dave,

Donald C. Williams (in 'The Myth of Passage', J. Phil. 1951, at pp. 468-9) discussed the possibility of a time-reversed doppelganger whose experience runs backwards relative to everyone else's because of a perfect reversal of physical events within the doppelganger's body.

I'm very interested in the whole issue about experiencing temporal passage. One can argue (at any rate, I do!) that veridical time perception is impossible - that we could not experience mind-independent temporal passage even if there were such a thing. Very briefly, the argument is that temporal passage would not be the kind of thing that could have a role in determining physical states and thus could not have a role in shaping conscious experiences that supervene on physical states. Real, mind-independent passage therefore cannot be perceived or 'experienced'. Moreover if passage cannot be experienced then it's questionable whether we can even say that experience falsely represents time as passing, because there's a question about how mind-independent temporal passage could be represented by a feature of conscious experience at all. Some other story would have to be told about what this feature of consciousness represents. And at that point it becomes questionable whether it's coherent even to claim that time passes mind-independently, regardless of how one argues for the claim, for one loses one's grip on what is being claimed. If that's all true then the existence of what we call 'experiencing the passage of time' goes against the A-theory rather than in favour of it as is commonly assumed.

What I do find very difficult in relation to this issue is that I sometimes meet people who deny that temporal passage (in the A-theory sense) is a feature of their conscious experience at all. They typically accept that one has a retrospective sense of time having 'passed' since some remembered event, but deny that there is any more immediate awareness of passage. I cannot easily believe that their phenomenology differs so much from mine - I think that there's an important sense in which experience presents us with a world in which things seem to objectively 'change' (where this means more than that they are in one state at one time and in another state at another time) - what Williams called 'the jerk and whoosh of process, the felt flow of one moment into the next' (p. 466) - but when faced with a sceptic, the precise nature of the experience becomes remarkably elusive.

Ignacio Prado

Quoting Simon Prosser:

"Very briefly, the argument is that temporal passage would not be the kind of thing that could have a role in determining physical states and thus could not have a role in shaping conscious experiences that supervene on physical states."

I am confused about what the claim would be here: what exactly is involved in some objective property of the environment having a role that "could" determine the physical states that our experience of that property supervenes on?--and why is objective temporal passage excluded from playing such a role?

It can't just be a lack of structural isomorphism between the supervenience base of the experience and the content of the experience. The squareness of my computer screen presumably plays a role in determining the physical states of my brain that my
(presumably) veridical experience of squareness supervenes on (assuming, for ease of exposition, that the content of experience is narrowly deteremined). Certainly, the squareness of my computer screen plays this role without there needing to be a structural isomorphism between the supervenience base of my experience (i.e., my brain states) and the property of my environment that is the content of that experience. In effect, my brain states do not need to be arranged squarewise for my experience of squareness to be veridical.

Would there be something deeper than a lack of structural isomorphism between the content of experience and its supervenience base that would prevent a notional property of objective temporal passage from playing the right role in determining the physical states that my experience of temporal passage supervenes on?

Philippe Chuard

Dave, just a small point about what you mean when you write:

“I think one can argue that at least at the level of representation, experience represents time as passing in a robust A-theoretic sense, so that Eden (the world where our experience is perfectly veridical) is a world of temporal passage, rather than a “block universe”. Of course this does not entail that our world is such a world: as with color experience, our temporal experience might be only imperfectly veridical.”

Is the idea that, properly considered, the phenomenology of experiences of succession of events entail that their contents represent the flow of time in A-terms? If so, I'm not so sure. I agree with you that B-theorists could always question the veridicality of such experiences. But it seems that another route is available to them in resisting the argument from experience.

I'm happy to grant that we may naturally describe the phenomenal character of such experiences in A-terms. But is this really the best description? It seems that B-theorists can always redescribe the content of such experiences in a way that’s compatible with their phenomenology.

What would be the content of an experience of temporal passage in A-terms? Presumably, something like this:

(AC) event W is present now & (later, event W is past now & event W’ is present) & (even later, events W and W’ are past now, event W is later than W’ & event W” is present) & ….

Admittedly, this paraphrase of the A-content of an experience of temporal passage is less than ideal. Hopefully, it’ll do for the point to go through. Again, it seems as though B-theorists can redescribe the content of such an experience as follows:

(BC) even W is co-simultaneous with this experience E & (later, event W and experience E are later than this experience E’ & event W’ is co-simultaneous with this experience E’) & (even later, event W and experience W are later than this experience E”, event W’ and experience E’ are later than this experience E”, W and E are later than W’ and E’, & event W” is co-simultaneous with this experience E”) & …

Or something along these lines. Now, it seems that if (BC) captured the content of such an experience—rather than (AC)—there is no reason to think that the phenomenology of that experience would differ. At least, I don’t really see how it could. Am I missing something? If not, there is no entailment from the phenomenology of such experiences to the claim that they have an A-content.

By the way, a bit of shameless self-promotion: for a slightly more detailed discussion of this point, and further attempts to clarify the issue, see BrainPains (a new group blog in the philosophy of mind).


Hi Philippe,

I think an A-theorist might deny that (BC) adequately captures the content. But in any case, my thought didn't turn on the difference between attributing properties such as presentness, as in (AC), and attributing relations such as later-than, as in (BC). Rather, the idea was that whenever experience attributes temporal properties and relations -- whether presentness, pastness, later-than, or whatever -- it's attributing properties and relations that require temporal passage of a sort that's not present in a B-theoretic "block" universe.

One could put the view by analogy with the Edenic view, according to which for a color experiences to be perfectly veridical, the world would have to contain perfect redness, a primitive qualitative property. That property may not be instantiated in our world, if it's purely physical (or physical/phenomenal) -- instead, objects in our world instantiate imperfect redness, e.g. the physical property that is the closest match). Likewise, one might hold that for a temporal experience to be perfectly veridical, the world would have to instantiate "perfect" temporal properties and relations involving temporal passage. Those properties and relations may not be instantiated in our world, if it's a B-theoretical block universe -- instead, things in our world instantiate imperfect temporal properties and relations, e.g. physics-based properties that don't require passage.

Note that if this view is correct, it applies just as much to (BC) as to (AC). If (BC) were to mirror the perfect veridicality conditions of the experience, terms such as 'later' would have to be interpreted as invoking passage-involving relations.

I don't know whether this view is correct, but I think there's something to be said for the idea that phenomenologically experience presents our world as a world where there is passage. Of course as with all phenomenological claims, it is not easy to turn this phenomenological intuition into an argument.

Adhanom Andemicael

Dear all,

My paper "Temporal Passage" was posted in the Karl Jaspers Forum (KJF) on
the 8th of July, 2003 as "Target Article 61." The forum's website address

The paper can also be accessed at my website:

Please read the article. And if you have any comments, please feel free to
post them at the KJF site.

Best regards,

Adhanom Andemicael

Robert Howell

Hey Dave,
I've been wondering about your response to Philippe, and I posted a couple of interpretations of it back on BrainPains. ( I'd be curious to know if they capture what you had in mind.

Simon Prosser

A quick reply to Ignacio Prado's question (but I'll keep it brief because I don't want to hijack Dave's blog to discuss my own ideas! Sorry for the slow response - I was away). Structural isomorphism between content and supervenience base is indeed irrelevant. Consider a visual experience of a computer screen. We have a story we can tell about how the computer screen exerts a causal influence on the brain, changing its state and thus bringing about the perceptual experience (which at least supervenes on the brain state). Related to this, a common way to understand the notion of representation has it that there has to be some kind of covariance or dependency relation between what is represented and whatever does the representing - in our example, a dependency relation between the state of the computer screen and the resulting brain state upon which the perceptual experience supervenes. The state of the brain, and hence the nature of the experience, depends on the state of the computer screen.

The problem about experiencing temporal passage is that it doesn't seem possible to tell any analogous story about how a brain state (or anything that supervenes upon it) could represent the passage of time. If the brain state (or mental state that supervenes upon it) represents the computer screen, it had better be the case that the configuration of the brain is the way it is because of the computer screen being the way it is. But (or so I claim) there is no corresponding way in which the configuration of the brain could be the way it is because of time passing and consequently no way in which our temporal experience could be the way it is because of time passing. A-theorists and B-theorists don't disagree over the laws of physics or initial conditions; but initial conditions plus the laws of physics are all that determine the configuration of the brain (assuming the causal closure of the physical).

There are objections that can be raised here, but I haven't yet seen one that I've found convincing. For what it's worth, I think there are some parallels between the issue of how we could experience temporal passage, and say that we do, and the standard question of how we could experience epiphenomenal qualia, and say that we do (the problem being that an utterance involves a change in the configuration of the physical world).

Waldo Skipsey

It may be that experience or conscienceness is 'temporal passage'

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