No, it has not been.
Many creationists would be content to end this essay there, but in reality, the situation is not so simple. To argue against the theory of evolution by saying that it “hasn’t been proven” is to demonstrate a severe misunderstanding of the nature of science, which this essay will endeavor to correct.
It is true that the theory of evolution has not been proven – if, by that term, one means established beyond any further possibility of doubt or refutation. On the other hand, neither has atomic theory, the theory of relativity, quantum theory, or indeed any other theory in science. The reason for this is that science does not deal in absolute proof, only in the balance of the evidence.
To see why this is and must be true, imagine that we are scientists seeking to explain some feature of the natural world. Based on the evidence available to us, we can construct a hypothesis – an educated guess – which we offer as that explanation. If more evidence turns up that supports our hypothesis, if our hypothesis is testable and falsifiable, and if our hypothesis can be used to make predictions which turn out to be correct – if all these things are true, then our hypothesis graduates to the status of a theory and, in time, becomes accepted scientific wisdom.
But how do we really know the original hypothesis is true? What if it completely misses the mark, but gives the right answers just by coincidence? Or what if it is just an approximation, giving generally correct answers while failing to capture the true reality of what is going on? How can we ever be sure that these things are not the case?
The answer is, of course, that we cannot know this. This is why no scientific theory, including evolution, is ever considered to be proven. The more evidence that accumulates to support a theory, the more our confidence in it grows. Eventually, a point may be reached where the quantity of evidence supporting the theory is so vast, so overwhelming, that further attempts to deny or question it would be futile and unfounded. This is the case with the theory of evolution, as it is the case with the other theories, such as the atomic theory of matter or the theory of plate tectonics, that form the pillars of modern science. But this is not absolute proof. Not even the best-supported, most thoroughly verified theories of science are put on a pedestal and considered infallible, since at any time, some shocking new piece of evidence might turn up that completely contradicts accepted knowledge. We have no way of knowing that this will not happen in the future.
This is not to imply that the theory of evolution is in any way tentative or uncertain. On the contrary, it is extremely robust, backed by over a hundred years of research, experiment and observation. In all that time, not a single piece of evidence that seriously contradicts any part of it has ever turned up. Within the scientific community, evolution is not at all controversial and is no longer questioned; it is considered to be a fact, as simple and indisputable as gravity. While it can never be absolutely proven, it has come as close to attaining this status as it is possible for any scientific theory to be. To attack evolution by labeling it an “unproven theory” misses the point entirely. There is a saying in some scientific circles: “Proof is for mathematics and alcohol.”