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Why is it that we can change the future, but not the past?

A distinction must be made when talking about the past (and to a lesser degree the future) between objective truths about events that 'happen' and our perceptions of them. We name the perceptions of the past 'history' and it is my hope to prove that any attempt to study the objective events should be considered both impossible and futile. The study of history involves investigation of evidence which exists in the present, and no direct evaluation of anything in the past. A 'good' historian sticks solidly to the evidence that he has about the past, extrapolating where there is room, but never attempting to use anything but that which exists in the present - evidence, whether primary or secondary - to build up a picture of history. A 'bad' historian would be one that completely failed to use evidence still in existence to talk about history, claiming, for example, that the Battle of Hastings in fact happened in 1065. Regardless of whether the 'objective truth' is that the battle happened in 1065 it would be laughable and pointless to make such a claim with no evidence. History, therefore, does not care about 'objective truth' (in fact it cannot concern itself with this) but with the picture that can be painted using the evidence we have in present. A discussion about whether the historian who claims the battle occurred in 1065 is correct is meaningless and will not lead anywhere, since there is currently no evidence that can conclusively prove that this was in fact the case, and any such evidence that might be discovered in the future is not safe from refutation by new evidence itself. Historians have a near total consensus that the Battle of Hastings occurred in 1066, and therefore this is what history records about the date of the battle.

If the Battle of Hastings did, in fact, occur in 1065 (though I do not wish to dwell on statements such as this, since I am not happy about anyone making statements about 'what in fact happened', when these seem not to mean a great deal) no amount of evidence can affect the truth of this occurrence, and no amount of evidence could make this truth false, all that evidence can do is extend the breadth of human knowledge - it never has an interaction with the truth of the events. Ayer points out that truth is independent of time - that 'The Battle of Hastings was in 1066' is true or false whenever someone says it, and the truth or falsehood will never change, only what we know about. History cannot care about making statements that are objectively true, and understanding this must surely breed the same view of the future.

Equally when talking about the future we must make a distinction between the future as it is perceived, and the objective events as they happen. When talking about the perceived future the instinctive feeling is that we are able to change the future in just the way we are unable to change the past. It is my hope to show that in respect of perceptions of the past and future it is entirely possible for alterations to occur in either direction, and in respect of objective truths both directions are just as fixed and closed to change.

When it comes to the perceptions of the past it should be apparent that 'history' can change. New history books are written every day, yet nobody would claim that these change which objective events happened in the past. What they do change, however, are our perceptions of the past, and as new evidence is discovered, or the old evidence is re-examined, it is entirely possible for history to advance. We could, for example, discover that our crackpot historian becomes the holder of a popular view, if new evidence comes to light that makes it seem very likely that the Battle of Hastings in fact happened in 1065. The objective truth about when the battle actually happened is still pretty much unimportant (it would be lovely to get it right and pick just the right day and time for an event to happen, but it is only ever meaningful if your choice of date is not random but based on evidence) and the objective truth is not going to change, but this should show that history - the perception of the past - can change. So what is different about the future?

If a friend of mine were considering playing the lottery, I, being the cynic that I am (and knowing the odds involved), might look him in the eye and tell him 'You won't win the lottery'. His response would almost certainly be 'I might', and, whilst the odds would claim that there is a very small chance that he will win, I am in fact right in telling him that he won't win the lottery. The fact that my friend might wait till Saturday to discover that he has failed to pick that numbers that correspond to those randomly chosen as the winning numbers may give him satisfaction and enjoyment from playing the game but they don't mean that he is right to suggest that he might win and that my statement is wrong until Saturday comes and proves it to be correct. As Ayer points out, the truth of a statement must be independent from time, and a statement cannot at some moment along the time suddenly become true, but is either true or false (or meaningless) from the moment that it is uttered. I am no more correct (though I can feel vindicated) come Saturday when the truth of my statement is demonstrated - but this is a matter of perception of events, and the demonstration of the truth of my statement is something entirely different from it 'becoming true'.

It is possible for me to make the statement that you, the reader, will be sitting down when you read this essay, and that statement is either true or false already. If when it comes to someone reading the essay they choose to be sitting down my statement will be true - but we must not mistake the tense of the sitting or reading as indicating something about when the statement is true - it is true always or never, regardless of when the statement is made.

If I were to say 'My friend Jamie is currently in London' I expect that most people would agree that this is either the case or not the case, and would agree that I could discover whether he was in London or not by phoning and asking him, and thus discover whether my statement was true or false. Even less contentious would probably be the statement 'My friend Jamie was in London last week'. Someone would be very silly to make a bet with me about whether this statement were true or false - being my friend I'm likely to know whether Jamie was in London - but again people would probably agree that either this is the case or it isn't, that my statement is either true or false, and that a quick phone call could sort it out. If a bet had actually been taken up more concrete proof would probably be needed, but the other gambler would probably be happy to wait for Jamie to come up on the train bringing a photo of him in London last week proving beyond any doubt that he was there. I would think it very strange if the other gambler refused to wait that long for fear that in the two hours it would take Jamie to get here the truth about whether he was in London last week might change.

Both these examples require us to accept that truth is independent of our knowledge of that truth, and that Jamie was where he was and is where he is regardless of whether we know just where that was or is. Dummett introduces the example of a tribal chieftain who performs a tribal dance which he believes will affect how bravely tribe members will fare on a hunt. What Dummett questions is whether there is any point in the chieftain continuing to dance during the period when he knows that the hunters will be on their way home, and will have already shown bravery or not. Dummett is right to question whether the chieftain's actions make sense - like my gambling friend he may be ignorant of how events have gone (and specifically whether the tribe members have hunted bravely), but it seems nonsensical for him to still expect the result to change or be affected in any way by his actions when he knows that the hunt is in the past. Dummett strangely seems to want to put down the chieftain's action as exhibiting a belief in backwards causation on the part of the chieftain, rather than accepting that it seems to be a widely held view (simply for lack of thought about the issue) that knowledge of truths seem to affect those truths.

Why then should events in the future be any different? Why do we give them a special status that just because we don't know what will happen we claim that statements about the future can't be true or false? The answer is that we should not - that anything we might say about the future is already true or false and that will not change, and in that sense it is not possible to change the future. Any alteration to what we currently perceive as going to happen will not change the future, but move it in line with what actually is going to happen.

If I say 'Jamie will be in London next week' this is a statement that is either true or false. The fact that I don't yet know whether he will be in London next week is beside the point - I can always wait and see whether the truth of my statement is confirmed or proved false, either way my statement won't become true or become false, I will merely find out whether it was true or false all along. If I were to phone up Jamie and ask him to come and stay with me for a week and he accepted I would not be altering the future, but putting it on the path it was always to be on. If I were to do this I wouldn't be making my previously true statement false, I would be moving towards the discovery that my statement was false all along.

In fact, the example of whether someone is sitting reading this essay is masking a more complex statement, or rather set of statements, because, since there may be more than one reader of this essay, the sentence is a statement about each individual case, since each reader may independently be standing, sitting or lying, for example. Each individual statement, however, is already true or false, and doesn't suddenly gain truth or falsehood mysteriously every time somebody read the essay. This does however open up a very interesting question.

If I were, instead of claiming that a single reader would be sitting down when reading this essay, to make a larger claim, and say that the majority of readers of this essay will be sitting down when they read it my prediction of the future takes a very different shape. The reason this statement is so different from the others is that, whilst it appears to have content, and to be a statement that is indeed either true or false (almost even more so than the statement about individual readers, since this one only involves a single truth, not many) it should be clear that it will never be possible to say whether it is true or false. Regardless of how many people have read my essay it would always be possible for someone else to come along and read it, and therefore we can never tell whether the majority were sitting down or not when they read it.

A better example might be Descartes Meditations. Countless numbers have already read this book, yet if we were to find out about every one of those people, and discover whether they were sitting down when they read it, we would be no closer to discovering whether the majority of people who read his book will be standing up or sitting down. However long we wait, in fact, there will probably never be a time when nobody else could read his book and so, whilst it is possible to make a statement about the future that makes sense and is either true or false, waiting and seeing cannot demonstrate whether the statement is true or false itself. The sensible response to this would be 'So we'll never know, until the end of time, whether the statement is true or false? Isn't it rather a pointless statement to make, then?'. The answer, of course, is yes - if we can never find out, except by waiting till the entire human race has died out, whether this statement is true or false, it's not a very useful thing to say - but I hope that it demonstrates that there are statements where it would be senseless to claim that we have to 'wait and see' whether they're true or not because, whilst they seem to quite easily have a value of true or false it would be very difficult to discover which is the case.

Non-time specific statements are very much like this as well. If I were to say 'The Battle of Jub-Jub will happen in a place of the same name' I would have to wait till the end of time to be proven wrong, regardless of the fact that nowhere called Jub-Jub currently exists, or that we have no reason to presume there would be a battle there if it did. Conversely we can be pretty certain of the truth of a statement such as 'The sack of Troy happened entirely before the common era' because Troy has now been destroyed, and it isn't possible for any more sacking to go on. Even if another city called Troy were founded, it is obvious what is meant by the statement, so its validity could be challenged only by the strictest pedant. Equally we know that what is called the common era has now been reached, so with the period BCE complete it is easy to make a statement of the form 'The period BCE contained the sack of Troy' and to be almost completely certain of the truth of the statement.

It might be tempting to claim that statements can become more and more true (or more and more false) as we get nearer to the time involved with an event, but this is surely another mistake where the perception of the future is being taken for the actual future. The fact that a punch has been thrown might be a very good indication that I will be hit, but that doesn't make it any more true that I will be hit than ten minutes before when I started an argument, or a week before when I hadn't even set eyes of the person who has just thrown a punch. The person that says 'That's going to hurt' is no more correct than the person ten minutes earlier who said 'You're going to get hit for saying that' - the event itself is only proof of this fact.

Whilst we have to trust to our sense of induction that the sun will rise tomorrow it is not now any more likely that it will purely because we know how the solar system interacts, and can be pretty certain a colossal event that changes the way everything works won't happen. The statement 'The sun will rise tomorrow' is already true or false, and we can happily wait to see what happens, but we can't say that it is more likely to do so, simply by virtue of understanding the way things work. Equally the fact that we don't know whether the sun will or will not rise tomorrow is entirely independent, and cannot affect the truth itself.

I am sure that I am not the only person who has experienced annoyance when, having debated at the beginning of a day whether I should take a camera with me on a trip, I find myself wanting one when I had decided not to take it. There is always a niggling feeling in my mind when that happens that if I had brought my camera with me that day I would have found I didn't need it. These feelings are easy to explain psychologically - I notice the times when I choose not to take a camera and find myself wanting one, or those when I bring one along and feel it is only weighing me down since there is nothing I want to photograph, and these circumstances make a much greater impression than when I take along a camera and use it - but clearly the connection being made is a false one. Whilst bringing a camera may have a small effect on your day - if finding it makes you take a little longer and forces you to hurry you might notice the world around you a little less and thus fail to see things you might like to take pictures of - it is not likely that it will have the effect that I seem to feel it has had. In fact, most people would state that I was just imagining something that simply wasn't true, and in doing so they are supporting the view that whether I saw photograph-worthy material during the day or not was independent of whether I took a camera or not, and that the statement 'I'm going to see something worthy of taking a picture' is true before I set out. Since I can't know whether I will or not this revelation is no use when trying to decide whether I should take a camera or not, but it should stop me from having a perverse suspicion that a malignant demon is out there trying to prevent me from getting good pictures.

In short, therefore, whilst it may seem like we are able to change the future we can't in fact change the objective events that are going to happen. But it does seem like we can change things, and this instinct is well-founded, since, in exactly the way it is possible to change the perceptions of the past (history) we are in some control of the perceptions of the future. We are able to speak about what will happen at a given moment with a greater degree of certainty the nearer the time, and we are able to alter what we perceive is the way that things are going, and what we think is going to happen. These changes of perception are what we instinctively feel we can bring about - we are able to find the evidence (and provide the evidence) for a certain event in the future in a much more direct way than we are able to shape the evidence of the past, and can feel much happier with ourselves doing so than if we were to deliberately alter history by shaping the evidence we have of the past.

But ultimately am I committing to a determinist position, and saying we have no choice in our own destinies? The only way I could answer that would be to say that I'm sure when it came to Pinnochio objective events in the future would be very important - since statements about the future are already true or false he'd have to be very careful about what he said, or he might find his nose growing to extraordinary length as he made claims about a whole host of things about whose truth he could know nothing - for most of us it is the perception that principally matters. We can directly affect what we discover to be true, and the knowledge we gain about events that have not yet happened - but to ask to be able to change an already false statement to be true, or make a true statement false is something we'd have to be very greedy to demand. Pinnochio could happily base his life on a fear of making statements which are not true, but anyone else who altered their lives on this basis would seem rather foolish.

A number of philosophers, Ayer being no exception, seem to worry too much about our inability to change objective truths about the future, in much the same way that many historians would object too strongly to the suggestion that they are not trying to find out about objective events of the past. The morals to be learnt from history are not invalidated if we discover that the events we based such lessons on did not happen exactly as we thought they did, or even less so if they didn't happen exactly when we think they did. In just the same way we can learn from our perceptions of the future, and if we see ourselves heading in a direction we don't like we can work out what it is we can do to achieve a situation where the road ahead does look good. Ultimately the fact that a statement is true or false the moment we make it shouldn't make a difference to our lives, except to remind us that when something bad happens over which we have no control we just have to grin and bear it.