Our present model of the universe with planets orbiting stars, stars inhabiting galaxies which are themselves members of clusters of galaxies, all inhabiting the framework of Spacetime - is based upon a number of unprovable assumptions.
We assume that the universe 'in itself' has a direct correspondence to our perceptions. We also assume that it, and the things that constitute the universe, all continue to exist even when they are not being perceived. These are useful assumptions, but they can never be proven. We assume the future resembles the past, both in content and in form. By this we mean that we assume that cause will always precede effect, old age will always follow youth, and so on, without any exception. We also assume that Time itself will continue as we have known it - that each instant will occur once, and only once, and that no two instants will occur simultaneously. By this we are assuming that Time will continue to proceed in the orderly and linear fashion we have come to expect of it.
This model of Time assumes Future and Past. But it is impossible to prove the reality of either. If we took the position of an atheist, accepting only that which can be proven or demonstrated, we would have to reject the concepts.
We cannot see, touch, hear or smell the Future, it has no physical attributes whatsoever, neither can we study it by its effects. Yet we insist that it is somehow `real'. Such an entity which is real, but which has no physical characteristics must be metaphysical.
The same is true of the Past. The evidence of memory suggests the Past, but does not offer proof. Memory is a psychological event which, every time it occurs, it occurs in the Present. And, even so, it is uncertain evidence at best. Every moment we are forgetting things that did happen, and it is a commonplace in court testimony that witnesses often remember things that did not happen. We tailor and embellish our memories, which makes their value as evidence ambiguous.
The evidence of history - documents, artifacts, videotapes and film - also suggests, but does not prove, the reality of the Past. Again, every time we observe these artifacts, we observe them in the Present. They offer no self-evident reference to the Past. It is through our interpretations of these things that we conclude, or hypothesize, the category of `Past Events.' Unambiguous `proof' of the reality of Past and Future is simply not there to be found. Our insistence upon the reality of past events is a conjecture, one we use to explain how such things come into being in the Present. Our need to believe in the reality of past events is a cognitive fiction, an emotional crutch so to speak, which supports us in our wanderings through an eternally present Time. In a sense, we are anthropomorphizing Time when we partition it into Past, Present and Future.
Though all these assumptions are useful, and help us make sense of our experience, they can never be proven. Science cannot address these assumptions, for they go below the scope of experimental method. No experiment can prove or disprove the hypothesis of future events. No observation can confirm or disconfirm the hypothesis.
Neither does Science have the language to address these matters. We must draw our terms from other languages - those languages which treat explicitly with the unprovable, the languages of Metaphysics, of Faith, of Magic, and even of Deception and irrationality.
These assumptions are either one of two things for us. Either they are merely assumptions - which means that we have never given them any serious thought - or, if we have given them thought, they are articles of faith. This would be a pragmatic faith. Since we cannot prove that the sun will rise tomorrow, and since worrying about it is largely a waste of time, we decide to let the matter rest, and accept it on faith that the Sun will continue to do what we have always seen it do.
The model presented to us by science assumes all these matters, and begins with the model inherited by previous observations and conclusions. Speculative philosophy, however, cannot be so assured. With unqualified skepticism one of our basic principles, wherever we find an assumption, any assumption - we must refuse to accept it until we have given ourselves meaningful grounds for doing so. And we must come to meaningful conclusions about this assumption before we can progress any further in our inquiry.
We begin only with those matters which are impossible to doubt, and which are based upon
primary experience our own perceptions. As Descartes demonstrated, I cannot doubt my
own being without proving it. From this solid ground, I can explore further. But with each step
outward, I necessarily invoke another level of doubt, which brings with it a corresponding level
of skepticism.
It is extremely probable that I am not alone, that other human beings exist independently of me, even when I am not perceiving them - but this I can never prove, I can only assume that when a person I encounter in waking life asserts `I am real', this assertion is somehow different in character than the same assertion made by a figure 1 see in my dreams. But I cannot prove this. That you exist at all is fundamentally a matter of faith for me. Likewise is your belief in my existence a matter of faith for you or of unthinking assumption.
From this beginning, we have much to study, and many assumptions to resolve before we arrive at the model of the universe presented by Science. And by the time we have got there, the level of doubt has come to be extremely high.
Does the universe truly exist independently of me, or is this belief something I accept only for emotional reasons? I must ask myself - do I accept this model solely on the authority of others? Do I accept it because 1 want to appear intelligent, or because I fear ridicule from the majority, or because I want to enjoy the company of those who do accept this model? These are not sufficient grounds for accepting the assumption. It is a matter of common knowledge that authorities are sometimes wrong, and it is also a matter of fact that false beliefs have been very widespread, and have held sway for whole centuries.
Again, I must ask myself - is it only because I fear the absurdity of the alternatives that I choose to believe the sun will rise tomorrow? If this is so, my fear of absurdity is also not sufficient reason to accept this belief. It is prerequisite to our studies that we abolish in ourselves this fear of absurdity that is so basic a characteristic to our species, for this fear of absurdity is itself nothing but an irrational bias, one which skews our observations.
At last we can conclude that the model presented to us by Science is useful, and we can work with it, understanding it to be tentative in nature, and by no means absolute. It presents us with a road map of sorts, and like every road map, it is not reality itself, but simply a useful representation of reality one which, like every other map ever drawn, must ignore ambiguity and a host of transient details to present a useful representation, and one which is subject to constant revision.