I think free will, our ability to act as author without being determined to act in a certain manner is real, and it does not require a leap of faith. The physical causal argument that I am determined to do x because of some other event y does not work in the narrative I tell myself about the world — Cavacava

LOL. I can tell all kinds of narratives (in one of my favorites I'm the best at X- and I don't want to tell you what X is.) It doesn't make them true, or agree with what is the case. How would anyone go about proving that free will is the case? I am operating under the assumption that it can't be done.

One might as well try to prove that God does or doesn't exist.

Which statement(s) in that article to you take to imply that the block theory is the received view? — Terrapin Station

The article indeed seems to portray the view as being, if not contestable, at least contested. While Andreas Albrecht was defending it, Avshalom Elitzur, Lee Smolin and George Ellis were arguing strongly against it. Jennan Ismael, a philosopher rather than a physicist, was only arguing that our experience of the flow of time is consistent with the block universe view.

Right.

And the article certainly isn't stating that the block theory is the received view in the sciences.

The article indeed seems to portray the view as being, if not contestable, at least contested. While Andreas Albrecht was defending it, Avshalom Elitzur, Lee Smolin and George Ellis were arguing strongly against it. Jennan Ismael, a philosopher rather than a physicist, was only arguing that our experience of the flow of time is consistent with the block universe view. — Pierre-Normand

The physicists, many of whom are prominent experts, who do not like the block-universe implication of Relativity, are doing the right thing - they are trying to discover new physics. They have to do this because they are experts, and they know relativity implies the block. Best of luck to them because they have met with zero success so far!

They have to do this because they are experts, and they know relativity implies the block. Best of luck to them because they have met with zero success so far! — tom

Well, that is your own assessment of the situation. While general relativity on its own may suggest (rather than logically entail) something like the block universe view, quantum mechanics rather suggests that the fundamental laws of physics are non-deterministic. There also are no-collapse interpretations of QM, such as the many-world view, that may be construed as deterministic, but that would still make the evolution of individual coherent histories, as experienced by sentient observers such as ourselves, non-deterministic. The debate then turns on the question whether what we call *the* universe consists in the specific 'world' (or 'coherent history') that we are experiencing, or rather consists in the superposition of all of them (including 'worlds' or 'histories' in which we didn't evolve). In either cases, the issue would seem to have little relevance to the problem of free will and determinism. It doesn't make any contact with the compatibilism/incompatibilism debate, and it doesn't seem to conceive of nomological determinism at the correct psychological level of analysis such as to make it relevant to the possibilities of freedom of choice and action.

Secondly, even if we would grant that the "block universe" might consist in a superpositions of all the individual histories, it would still be quite unlike the classical block universe view suggested by relativity. We don't have a fully worked out quantum theory of gravitations, and QM has as much theoretical and empirical support as GR has. So, what gives? You seem to favor the block universe as a matter of personal preference and hence take GR to trump QM.

Finally, universal determinism -- either of the causal or nomological varieties -- are philosophical doctrines that can not be decided merely on the basis of physical theory. The selfsame physical theory often admits of different philosophical interpretations, some of which are usually overlooked by physicists. Kantian views of the experience of time, for instance, are usually ignored by physicists, or, when briefly considered, are dismissed on the basis of crude misunderstandings. For some exceptions to this philosophical naivety among physicists, consider Karen Barad (Meeting the Universe Midway) or Michel Bitbol (Some Steps Towards a Transcendental Deduction of Quantum Mechanics and Reflective Metaphysics: Understanding Quantum Mechanics from a Kantian Standpoint).

Well, that is your own assessment of the situation. While general relativity on its own may suggest (rather than logically entail) something like the block universe view, quantum mechanics rather suggests that the fundamental laws of physics are non-deterministic. There also are no-collapse interpretations of QM, such as the many-world view, that may be construed as deterministic, but that would still make the evolution of individual coherent histories, as experienced by sentient observers such as ourselves, non-deterministic. — Pierre-Normand

General Relativity mandates a stationary space-time block. All general relativists admit this. Those who do not like it, for whatever reason, are engaged in overturning GR.

As I mentioned earlier in the thread (perhaps more than once), non-collapse versions of QM lead to the Wheeler-DeWitt synthesis of GR and QM, which surprisingly has achieved some experimental corroboration. The wavefunction is stationary and timeless, much like spacetime.

No idea what you think Coherent Histories has to do with this?

General Relativity mandates a stationary space-time block. All general relativists admit this. Those who do not like it, for whatever reason, are engaged in overturning GR. — tom

Einstein's theory of general relativity is a theory of gravitation that is formulated within the framework of classical physics. It is an obsolete theory, albeit empirically accurate at the macroscopic level. Everyone who seeks to harmonise GR with quantum mechanics is "overturning" GR, in a sense (just as GR itself overturned the special theory of relativity). It is better to say that the goal is to account for the empirical success of GR within the framework of QM. The Wheeler-DeWitt equation just is one step towards a quantum theory of gravitation, and there are alternative approaches (such as string theory).

No idea what you think Coherent Histories has to do with this?

Sorry, I meant to say "consistent histories". It is relevant since, as I suggested, the timeless wave-function describes a superpositions of all the consistent histories that we, as sentient observers, may experience, and hence its static nature doesn't entail determinism at the empirical level that interests us. The latter, as well as our experience of time, is a result of the decoherence of the timeless wavefunction into multiple independent consistent histories. If the laws of physics don't determine, given our own specific past history, what it is that we will experience in the future, then the mere consideration that all possible outcomes (i.e. all the outcomes not ruled out by QM) are somehow 'realized' in some coherent history or other (i.e. in some parallel 'world') is of little relevance to the issue of free will conceived as a capacity potentially exercised in one single 'world'.

Sorry, I meant to say "consistent histories". It is relevant since, as I suggested, the timeless wave-function describes a superpositions of all the consistent histories that we, as sentient observers, may experience, and hence its static nature doesn't entail determinism at the empirical level that interests us. — Pierre-Normand

There seems to be some inconsistency in your choice words here, which creates ambiguity. You refer to all the "consistent histories" which we "may experience". Correct me if I'm wrong, but "histories" refers to past events which may or may not have been experienced, and it is nonsense to speak of histories which we may experience.

The latter, as well as our experience of time, is a result of the decoherence of the timeless wavefunction into multiple independent consistent histories. — Pierre-Normand

What do you think could cause such a decoherence? Since our experience of time is key to our understanding of free will, then this decoherence must be of the utmost importance to this issue.

There seems to be some inconsistency in your choice words here, which creates ambiguity. You refer to all the "consistent histories" which we "may experience". Correct me if I'm wrong, but "histories" refers to past events which may or may not have been experienced, and it is nonsense to speak of histories which we may experience. — Metaphysician Undercover

I mean to be referring to the history of the world that we find ourselves in when we make empirical observations of any kind. It matters little for the purpose of the present discussion whether the events that are part of this history are past (inferred), presently observed, or reliably predicted. Consider the case of Schrödinger's cat. When we open the box, and find that the cat is dead, we can infer that it died more than an hour ago (because its body is stiff and cold, say), and also reliably predict that it will remain dead in foreseeable the future.

Even in those cases (most usual!) where our observations are observations of events that already are determined (as a result of the quantum wave-function of the observed system already being 'collapsed') -- such as our learning on the basis of historical documents that Caesar crossed the Rubicon -- we also are 'experiencing' (in the relevant sense) events that belong to our past history, and thus can rule out the possibility of our being part of an history in which Caesar wimped out. The past or the future aren't unknown to us just before they aren't 'directly' (meaning presently) observed by us.

What do you think could cause such a decoherence? Since our experience of time is key to our understanding of free will, then this decoherence must be of the utmost importance to this issue.

Decoherence, in the framework of the many-world (or consistent histories) interpretations of quantum mechanics, plays a role that is similar to the role played by the collapse of the wave-function (or reduction of the state-vector) in more traditional approaches such as the so called Copenhagen interpretation (which actually covers many interpretations). See the wikipedia articles on quantum decoherence and consistent histories.

Decoherence views (no-collapse), as opposed to collapse views (e.g. Copenhagen) have the advantage that they don't require actual measurements performed by intelligent agents to explain how macroscopic quantum systems become entangled and thus 'measure' each other, as it were. But they also have the inconvenience of leaving undefined the limit between the 'classical' and quantum domains. They promote a sort of a view from nowhere on quantum mechanical systems that isn't very appealing philosophically. One recent approach that has sought to overcome this limitation is Quantum Bayesianism. Michel Bitbols' work on the philosophical foundations of quantum mechanics is related to this and it directly adresses the issue of the cognition of time. But, as is the case with all of the above, however metaphysically enlightening, it has little direct relevance to the alleged problems of free will and determinism, on my view.

It matters little for the purpose of the present discussion whether the events that are part of this history are past (inferred), presently observed, or reliably predicted. Consider the case of Schrödinger's cat. When we open the box, and find that the cat is dead, we can infer that it died more than an hour ago (because its body is stiff and cold, say), and also reliably predict that it will remain dead in foreseeable the future. — Pierre-Normand

Actually it makes a big difference. Do you recognize a difference between the numerous logical possibilities of what may have occurred in the past when it is believed that only one of these possibilities is what actually occurred, and the ontological possibilities for the future, when it is believed that any one of these possibilities may actually occur?

When our attention is directed toward the past, we assume that one thing actually occurred, yet if we do not know what actually occurred, we allow logical possibilities for what actually occurred. We may proceed towards narrowing the possibilities, and determining what actually happened. When our attention is directed at the future, we assume many things may actually occur, these are ontological possibilities. We may choose a possibility as a preferred one, and proceed toward ensuring that this occurs. Do you recognize the difference? With respect to the past, we determine the possibilities, then choose the one most representative of what actually happened, i.e., what has been determined by the passage of time. With respect to the future, we determine the possibilities, then choose the one which we prefer, and cause it to occur.

Even in those cases (most usual!) where our observations are observations of events that already are determined (as a result of the quantum wave-function of the observed system already being 'collapsed') -- such as our learning on the basis of historical documents that Caesar crossed the Rubicon -- we also are 'experiencing' (in the relevant sense) events that belong to our past history, and thus can rule out the possibility of our being part of an history in which Caesar wimped out. — Pierre-Normand

OK, let's say that we infer from relevant documents, that Caesar crossed the Rubicon, just like any observation of any event, we infer from the relevant evidence, what has occurred. In this way, we are as you say "experiencing" the event. Now, how do you propose to extend this principle to the future, such that we "experience" what may occur?

All the relevant evidence, in relation to the future, indicates to us what may happen, what is possible to happen. But there is no way to experience the future event until it actually happens, in which case it is a past event. The evidence of "what may happen" cannot be construed as an experiencing of the event, in the same way that the evidence of what has happened can be.

Decoherence views (no-collapse), as opposed to collapse views (e.g. Copenhagen) have the advantage that they don't require actual measurements performed by intelligent agents to explain how macroscopic quantum systems become entangled and thus 'measure' each other, as it were. — Pierre-Normand

Well, I suppose I could I ask the question again, what do you think causes decoherence? All you've told me is what doesn't cause decoherence, measurement.

Michel Bitbols' work on the philosophical foundations of quantum mechanics is related to this and it directly adresses the issue of the cognition of time. But, as is the case with all of the above, however metaphysically enlightening, it has little direct relevance to the alleged problems of free will and determinism, on my view. — Pierre-Normand

What do you mean by "cognition of time"?

How can you say that this is not relevant to the problem of free will? Free will, to be real, requires the intuitive substantial difference between future and past. The fundamental principle is that we cannot change what has occurred,

LOL. I can tell all kinds of narratives (in one of my favorites I'm the best at X- and I don't want to tell you what X is.) It doesn't make them true, or agree with what is the case. How would anyone go about proving that free will is the case? I am operating under the assumption that it can't be done.

One might as well try to prove that God does or doesn't exist.

It may not make them true or even "agree with what is the case", but if you admit that you derive meaning from what you experience, and, that this meaning is not in the experience, then you admit what you are the author of your meanings which creates your own inner causality, and you are aware of this... that in my estimation is the basis of free will.

As a side note, I think the hard determinism position is a left-over from the belief in God's omniscience, and it is just about as capable of being proved.

Do you recognize a difference between the numerous logical possibilities of what may have occurred in the past when it is believed that only one of these possibilities is what actually occurred, and the ontological possibilities for the future, when it is believed that any one of these possibilities may actually occur? — Metaphysician Undercover

I think there is at least a fourfold distinction between logical, metaphysical, historical and epistemological possibilities (and there likely are several grades of metaphysical possibility). But you are quibbling away from my very simple point -- in initial response to your initial question -- that what is known to be actual (or epistemologically possible) from someones point of view extends further than the immediate present, such that it makes sense to speak of that person's history rather than our being constrained to talking merely of her present knowledge of her immediately present situation.

Of course there remains an essential asymmetry of past and future. From a merely theoretical/observational/passive point of view, prediction and retro-diction are very similar. When one learns, in the present, that a cat has been dead for a while, then one learns many facts about both the recent past and the nearby future. But, regarding the future only, can one know what will happen not merely through inferring it from known present and past constraints, but also through deciding what to do. Although the peculiar asymmetry that stems from this specifically agential perspective (i.e. our ability to control the future, and our inability to control the past) is relevant to the freewill and determinism issue, it is quite unconnected to anything that general relativity or quantum mechanics teaches us about the physical world, it seems to me. I think your concerns are completely different from Question's.

Now, how do you propose to extend this principle to the future, such that we "experience" what may occur? — Metaphysician Undercover

That's very simple. When Ceasar crossed the Rubicon, this became a historical fact. It will remain true in the future that Caesar crossed the Rubicon -- and similarly for everything this facts entails logically or nomologically. For sure, a wide range of future events are consistent with this past fact, which is why QM is a non-deterministic theory even under the many histories (or many-worlds) interpretations. It encourages a view of the 'multiverse' (of the universe's wave-function) evolving deterministically, but my main point against Question, is that it (QM), just like general relativity, is quite consistent with the world (our empirical reality) being non-deterministic from our empirical point of view. This is so precisely because our past history is consistent with a variety of future histories. But this is only tangentially relevant to the other fact -- which you rightfully call attention to -- that the future (our future) has this additional feature that we can determine some features of it it through deciding what do do, and aren't constrained merely to stand-back and wait for quantum indeterminacies (or other epistemic or historical possibilities) to randomly resolve themselves.

When our attention is directed at the future, we assume many things may actually occur, these are ontological possibilities. — Metaphysician Undercover

I think they're still logical possibilities.

Say you're in a casino and you toss a die onto a craps table. As the die tumbles along, you may imagine 6 different outcomes. But you know apriori that every event has only one outcome.

If the die lands with the 2 face up, it is impossible that any other number also is. So in what sense were there 6 possibilities? Only logically.

Well, I suppose I could I ask the question again, what do you think causes decoherence? All you've told me is what doesn't cause decoherence, measurement. — Metaphysician Undercover

That's because nothing is traditionally regarded to "cause" the collapse of the wave-function, or decoherence to occur. Decoherence just is a branching out of the possible consistent histories of quantum systems (and their observers), from some observational perspective. Also, I am not committed to any particular interpretation of QM. I am merely bringing up the many histories view in order to show that, even of Question is right, and there exists an all-encompassing timeless view of the 'multiverse' (as represented by the Wheeler-DeWitt formalism for quantum gravity) this fact has no bearing on either the non-determinism of our empirical physical laws (e.g. as those laws loosely constrain our empirical future from our own lived embodied perspectives) or to the topic of free will and determinism.

I think they're still logical possibilities.

Say you're in a casino and you toss a die onto a craps table. As the die tumbles along, you may imagine 6 different outcomes. But you know apriori that every event has only one outcome.

If the die lands with the 2 face up, it is impossible that any other number also is. So in what sense were there 6 possibilities? Only logically. — Mongrel

It may be the case the the die, while tumbling, already is set on a deterministic trajectory such that it is merely an epistemological possibility that it might produce an outcome different than the outcome that is poised to occur. This would indeed be a possibility that merely stems from our ignorance of the detailed physical circumstances. But I think Metaphysician Undercover can have two different kinds of possibilities in mind regarding the future, both of which can be regarded as ontological rather than merely logical/epistemological. The first one is the sort of indeterminacy that stems from the indeterminacy of quantum mechanical systems that limit how much the present state of the tumbling die restricts the future outcomes. Micro-physical quantum indeterminacies can quickly be magnified onto macroscopic indeterminacies under such chaotic circumstances as the multiple tumblings of a small object in a ragged environment.

The second sort of ontological possibility, quite unrelated to the first one (in my opinion) occurs when one considers what do do among some range of options -- to see to it that P, Q, or R, say -- then one has to pre-select such options, as being worth deliberating over at all, only when they are still open options rather them being foreclosed by past and/or current circumstances. That is, one makes sure that it is presently within one's powers to see to it that any one of P, Q or R could come to be true. It is a bit of a dogma of hard-determinism that when one actually decides to see to it that P, then this reveals the alternative options to have been merely epistemic possibilities rather than them having been genuinely open ontological possibilities. But this is where the debate about free will and determinism ought to lie, and quantum mechanics (or general relativity) have little relevance to it.

I think there is at least a fourfold distinction between logical, metaphysical, historical and epistemological possibilities (and there likely are several grades of metaphysical possibility). But you are quibbling away from my very simple point -- in initial response to your initial question -- that what is known to be actual (or epistemologically possible) from someones point of view extends further than the immediate present, such that it makes sense to speak of that person's history rather than our being constrained to talking merely of her present knowledge of her immediately present situation. — Pierre-Normand

You don't seem to be addressing the point. The point was that there is a fundamental difference between talking about someone's future, and talking about someone's past. By saying that we can talk about something other than someone's "immediate present", really misses the point, because I never mentioned the present, and I don't know what would be meant by someone's "immediate present".

But, regarding the future only, can one know what will happen not merely through inferring it from known present and past constraints, but also through deciding what to do. — Pierre-Normand

Let me put it this way, it is impossible to know what will happen without knowing what one will do. And, it is impossible to infer, without a doubt, what one will do, "from known present and past constraints". So it is impossible to know what will happen, simply by knowing present and past constraints.

Although the peculiar asymmetry that stems from this specifically agential perspective (i.e. our ability to control the future, and our inability to control the past) is relevant to the freewill and determinism issue, it is quite unconnected to anything that general relativity or quantum mechanics teaches us about the physical world, it seems to me. I think your concerns are completely different from Question's. — Pierre-Normand

If the principles of special and general relativity lead one to believe that there is no substantial difference between past and future, then we cannot say that the two are unconnected.

That's very simple. When Ceasar crossed the Rubicon, this became a historical fact. It will remain true in the future that Caesar crossed the Rubicon -- and similarly for everything this facts entails logically or nomologically. — Pierre-Normand

You seem to be missing the point of the question. You describe past events such that we know that they are true, because we experience them. We experience Caesar crossing the Rubicon, by reading about this. How can you say the same thing about future events? Can we read about what will happen in the future, then conclude that we have experienced this event by reading? Do you not find that there is something wrong with this principle? Do you really think that we can experience an event, and therefore know that it is true, by reading about it? Reading about an event gives us information about it which is other than the information given in experiencing it.

If the die lands with the 2 face up, it is impossible that any other number also is. So in what sense were there 6 possibilities? Only logically. — Mongrel

By saying "if the die lands with the 2 face up", you have produced a proposition which indicates that this has actually happened, the die has landed with the 2 face up. If this occurs, then it is in the past. The only way that the die can land with the 2 face up, is if this event is now in the past. Prior to this though, when the throw is in the future, there are six possibilities.

It is for this reason that we must maintain a clear distinction between past and future. Prior to the event occurring, it is a possibility, along with other possibilities. After it occurs it is an actuality.

quantum mechanics (or general relativity) have little relevance to it. — Pierre-Normand

I agree with that.

Prior to this though, when the throw is in the future, there are six possibilities. — Metaphysician Undercover

There are definitely six logical possibilities. When we say "The 2 has a 1/6 chance of appearing face up.", we're talking about logical possibility.

The other kind of probability would make an assessment of some number of die throws... say 1000. Note that this kind of probability has no bearing on a unique event. The number in the denominator would be 1, so whatever the outcome turns out to be, it had a 100% chance of happening. This is all just a side effect of the fact that every event has only 1 outcome.

You don't seem to be addressing the point. The point was that there is a fundamental difference between talking about someone's future, and talking about someone's past. By saying that we can talk about something other than someone's "immediate present", really misses the point, because I never mentioned the present, and I don't know what would be meant by someone's "immediate present". — Metaphysician Undercover

How is that a point that I am missing? How is that related to anything that was at issue in my argument with Question? I agree that there are fundamental time asymmetries in physics, in metaphysics, and in practical philosophy; and one never relates to one's past in the same way one relates to one's future. So I have no idea what your *point* is or what it is that I might have said that you disagree with. Ordinary quantum mechanics (as applied pragmatically to make predictions about the future or retro-dictions about the past) also recognizes a fundamental asymmetry since measurements yield a wave-function collapse, and there is nothing that yields a wave-function to un-collapse (baring some exotic 'quantum eraser' experiments). The "histories" of the many-histories interpretation of QM just are specific possible trajectories of individuals who make sequences of observations/measurements of their surroundings. The specific history one finds oneself in is determined post-facto. Hence, from any time-situated empirical perspective of an agent, at any given time, her *future* history isn't fully determined yet.

Again, to reiterate, my main point against Question was purely negative. Even if, in a sense, there is a formalism (Wheeler-DeWitt) that portrays the quantum-wave function of the universe (i.e. the 'multiverse') in a timeless fashion independently from any actual observation or determinate experimental setup, and this timeless perspective seems somewhat consistent with the "block universe" view of general relativity, the intelligibility of this formalism has little bearing on the issue of the determinism/non-determinism of the laws of physics that govern the evolution of the observable properties of our empirical world -- let alone on the topic of freedom and determinism.

Let me put it this way, it is impossible to know what will happen without knowing what one will do. And, it is impossible to infer, without a doubt, what one will do, "from known present and past constraints". So it is impossible to know what will happen, simply by knowing present and past constraints. — Metaphysician Undercover

This is my point also, and it is true regardless of whatever quantum-mechanics (or special or general relativity) may tell us about physical laws. I simply am puzzled as to why you may think I would disagree with this.

If the principles of special and general relativity lead one to believe that there is no substantial difference between past and future, then we cannot say that the two are unconnected. — Metaphysician Undercover

Yes, but my view, which I have defended in my discussion with Question, is that the theory of relativity merely is a theory about the metric of spacetime (i.e. about its signature and curvature) and it has little bearing on the topics of determinism or time asymmetry. The idea that the future already 'exists' because it would be part of the timeless "block universe" is a wrong inference from relativity or from speculative theories of quantum gravity. This idea seems to me to be philosophical confusion projected back onto physical theories that are neutral about those metaphysical issues.

Do you really think that we can experience an event, and therefore know that it is true, by reading about it? Reading about an event gives us information about it which is other than the information given in experiencing it. — Metaphysician Undercover

That seems to be an epistemological issue about our knowledge of the past that is quite unconnected to the topic of this thread. Myself, I think knowledge from testimony can be just as good, and oftentimes better, than knowledge acquired on the basis of perceptual experience. It is liable to be mistaken if miscommunication occurs or if the messenger lies. But there also are all sorts of ways for our senses to mislead us. This merely indicates that our abilities to acquire empirical knowledge (either through sense experience or testimony) all are fallible abilities.

There are definitely six logical possibilities. When we say "The 2 has a 1/6 chance of appearing face up.", we're talking about logical possibility.

The other kind of probability would make an assessment of some number of die throws... say 1000. Note that this kind of probability has no bearing on a unique event. The number in the denominator would be 1, so whatever the outcome turns out to be, it had a 100% chance of happening. This is all just a side effect of the fact that every event has only 1 outcome. — Mongrel

We treat the possibility as different from a logical possibility. We assume that the way in which one throws the die will influence the outcome. Therefore we assume that before the die is thrown, whatever the outcome turns out to be, did not have "a 100% chance of happening". How do you account for the incompatibility between this and your claim " whatever the outcome turns out to be, it had a 100% chance of happening"?

The point being, that despite the fact that every event has only 1 outcome, we treat "the event" as if it is not predetermined, and can be influenced by our activities. Therefore the nature of "an event" is such that it has no specific identity prior to occurring.


Thanks for the clear explanation Pierre-Normand. Here's one thing I still have a question about:

The "histories" of the many-histories interpretation of QM just are specific possible trajectories of individuals who make sequences of observations/measurements of their surroundings. The specific history one finds oneself in is determined post-facto. Hence, from any time-situated empirical perspective of an agent, at any given time, her *future* history isn't fully determined yet. — Pierre-Normand

According to what you have just told me, all of the histories are determined post-facto. But any particular history must have temporal extension, or it is not a "history". So from the perspective of being within a particular history, as it occurs, or even from the perspective of properly observing one of these histories, we would need a distinction between future and past, within the history itself, to account for the "flow of time" within the history.

Let's assume the empirical perspective of an agent now. If there are many-histories, which are "possible trajectories", how does the observing agent compare the position of the boundary between future and past, in relation to the different possible histories? Suppose we have a number of possible histories. Are each of them supposed to start and end at precisely the same moment in time, from the perspective of the observer, and proceed at the same rate of time passage in relation to the observer? Or, shouldn't we allow for some discrepancy here?

Yes, but my view, which I have defended in my discussion with Question, is that the theory of relativity merely is a theory about the metric of spacetime — Pierre-Normand

Well, that is at least a bit of progress!

Consider the Andromeda Paradox https://en.wikipedia.org/wiki/Rietdijk%E2%80%93Putnam_argument

According to relativity, whether an event is in your past or in your future is determined by your motion relative to it.

Good points, all.

And I agree that hard determinism has yet to be proved. I think it's more likely that I do have free will and that no one knows for sure what kind of universe this is (if a multiverse, do we have free will?) than it is that I'm living in the deterministic universe that is being asserted by hard determinists (one that negates free will).

To believe in a hard determinism that negates free will does require faith.

According to relativity, whether an event is in your past or in your future is determined by your motion relative to it. — tom

Yes, for sure. This is simply a consequence of the relativity of simultaneity. But the issue of the simultaneity of spatially distant events (that are separated by a space-like interval) has little bearing on the issues of determinism or agency. One still is able to affect only events that are located within one's future light cone. Whatever is either within one's past light cone, or outside of one's light cone altogether, is beyond one's ability to control. Since the regions delimited by one's light cone (that is, the light cone centered where one is located at a given time) are invariant, there effectively remains an absolute past and an absolute future from the point of view of an observer, at any given moment of her life, independently of her state of motion.

This seems lie a balanced view: http://arxiv.org/pdf/1104.4551.pdf

Belief in free will is a necessary precondition for any meaningful understanding of the world. To deny it is to admit you deny it because you are compelled to deny it. To argue against it is to admit you are compelled to advance those arguments regardless of their persuasive authority.

Only a lawyer would think that acceptance of the potency of argumentation is a precondition for meaning.

The word of the day is: Leadbelly.