A common lament which I have heard from the scientific community is that, in the words of Dr Lawrence Krauss--as cited by Professor Scott Carson--"U. S. adults are less willing to accept evolution and the big bang as factual than adults in other industrial countries." Such a lament--so common amongst the "scientific community" (which roughly includes scientists, philosophers of science, and a crowd of what can only be called scientistic groupies) in the States--generally centers on these two particular theories and the opposition they receive from "religion," by which is largely meant Christians in general and the fundamentalist or evangelical types of Christians in particular. The lament is squarely pointed, first at the "young earth theorists" (anybody who believes that the universe is less than billions of years old), and secondly (more broadly) at the "Intelligent Design" proponents (anybody who suggests that no theory of non-theistic evolution can explain all of the intricate details of life in its varied forms today). Although I am neither a young-earth creationist nor an intelligent Design proponent, I can at the same time find some fault with the worldview which Dr Krauss pines for.

Much of this problem is ontological in that "theories" (and, for that matter, "laws") are not necessarily "facts," properly understood. A fact is a thing which is objectively true in a settled manner, e.g. "the human lifespan may exceed 100 years." This statement is a fact, because there are indeed some humans who are alive and who are more than 100 years old. Newton's law of gravitation gives a law--it posits no mechanism for how and why gravity operates, but rather gives a nice mathematical formula for the gravitational force in a weak field--but is not a fact in the same sense as the previous statement. For example, the gravitational attraction between a black hole and a particle which is passing through the event horizon no longer obeys a simple F = -G m1m2/r^2 relationship. Evolution and the Big Bang theory are properly classified as theories, because they make sense of some (if not necessarily all) of the day we have available to us, and posit a mechanism for the development of complex organisms from simple ones (evolution) or for the beginning of the universe (big bang).

They are not, however, properly classified as "facts," nor is any theory properly to be called such. To do so is to posit that the theory in question is "complete," which entails several things. First, to be complete, the theory account for everything which it claims to take into account. This means that there cannot be exceptions or holes to be found in said theory: there are such hole sin both theories at the present. For example, evolution has not yet satisfactorily explained the development of the so-called "irreducibly complex" biological features of some organisms, nor the gaps in the fossil records. This means that the theory is currently incomplete. I should note, however, that this is not to say that the theory will never be completed in this manner*. The nonexistence at present of an explanation for these "holes" does not mean that there never will be such an explanation, contra Intelligent Design's assertion of the universal negative that no possible answers for these questions may be discovered by science without appeals to God.

Second, "completion" implies that nor further progress can be made concerning a theory. This was the mistake of most physicists during the turn of the last century, who largely believed that the set of theories and laws which comprise Classical physics (mechanics, electromagnetism, statistics) could eventually be combined in such a way to explain every interaction in the universe. There confidence was rocked by the Michelson-Morley experiment, which concluded that there was no ether through which light could travel in outer space; it was shattered completely by the discoveries of Quantum Mechanics and Einstein's relativity theories. No longer could every interaction be described in exact detail, because the uncertainty principle would not permit all of the details of position and momentum, or of energy and time, to be known. Nor have these two theories been successfully reconciled with each other, as the quest for a unified field theory or some other "Theory of Everything" proves.

Finally, the completeness of a theory requires that the theory be able to prove itself to be true, a part of which is the proof of absolute consistency. Yet, Godel's Incompleteness Theorems show that this last criterion is an impossibility, at least as can be applied to any mathematical theory: no such theory can prove its own consistency. Indeed, Godel's theorems have a wider set of implications, beginning with the mathematical sciences, and concluding with science writ large. Said theorems apply to any system which attempts consistency, and therefore they must include any science based on measurement and observation. This means all of the natural sciences, including the biological sciences which give us the Theory of Evolution and the physical sciences which give us the Big Bang Theory. Hence we are left with incomplete theories--which may yet be modified--and not necessarily with facts.
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*I should add, as a footnote, that I accept both the Big Bang Theory and the Theory of Evolution to be true theories as far as they go. I also think that progress will be made to answer at least some of the questions still posed to and by these theories. These are the best theories available for what they attempt to explain; the evidence which favors both is overwhelming, though this does not mean that either is complete.