What Exactly Is "Proof" In Science? Five Reasons Why Scientific Proof Is Different Than Other Kinds Of Proof
Have you ever had anyone tell you that "evolution is just a theory?" What about climate change? Or maybe someone claimed that proof was impossible in science? These objections commonly arise from a simple misunderstanding of terms or a lack of rigid oversight. Here are five reasons why proof in science is something much different than the colloquial usage typically indicates.
1) Scientific theories are not the same thing as speculative theories.
The word 'theory' is often used commonly to indicate speculation, or a guess that doesn't necessarily depend on solid evidence. Scientific theories, on the other hand, are vastly more complex. They are a cohesive web of facts, data, mathematics, statistics, and hypotheses, all working in unison. Scientific theories can make predictions, describe facts, data, and things we've observed, indirectly or directly. It's for this reason that climate change and evolution are theories in an entirely different sense than that of the guessing game kind. Scientific theories have real facts about how the world works, independent of their own predictive power and accuracy. In other words, if the models for predicting climate change were found to be inaccurate, it would still be a fact that CO2 traps excess heat in the atmosphere, which can radically alter the ecology of the planet.
2) Proof in science works a lot differently than that of math
Proof in science works by repeated observation, explanation, analysis, prediction. The more consistent the test results are, the smaller the uncertainty. In the real world, there's no 100% guarantee that anything has to happen in the real world (unlike 1+1=2), but when we get the same or similar results for a long period of testing, we know we've found something. Furthermore, we don't need 100% certainty to say we know something or have proof for it. If we've always seen (observed) the sun setting and rising from our perspective (or the Earth rotating), I think it's safe for us to say that we know it will continue to tomorrow by any reasonable definition of knowledge.
3) If we require absolute certainty to say that we know something, we know nothing
If you want to hold on to the notion that knowledge is 100% certain, you have to realize the implications that come with such a view. Math and logic are useful tools, but there's no evidence they are physically a part of the world. This means that science, or repeated experimentation and observation is the best thing we have. If you need 100% certainty to say you know something about the world, you do not know anything about the world by your definition. Which brings us to the self-defeating part: if you need absolute certainty to know something, shouldn't you be absolutely certain that you need absolute certainty to know something? (say that five times fast) In other words, by this very definition, a believer in it rejects the belief because it wasn't absolutely certain.
4) Falsified theories aren't thrown out - they still tell us much about how the world works
If a scientific theory, defined above, is shown to not agree with new data or provide the best model for predictions, it doesn't mean the theory as a whole is disregarded. In fact, there is often much we can use it for, even in ways that give us insights on how the world works. Take Newton's physics, for example. While superseded as the prevailing theory of physics by quantum mechanics, classical mechanics is still widely used in most engineering and practical applications. It's still very accurate and powerful at the levels of our immediate experience. Take bridges, electronics, or anything we've created in the past 200 years! It all uses Newtonian Mechanics in some shape or another. As for quantum mechanics, this just means that Newton's physics doesn't describe the whole picture of reality and only seems to be accurate at the levels of our own common experience. Even still, that doesn't mean we should disregard its predictive power at scales it does work at.
5) All knowledge about how the world works comes from science
Any knowledge that we have about the world should be testable, justified, true, and appropriately track what is being observed. Science, specifically empiricism, is the only means we have at acquiring that kind of knowledge. Mathematical truths are a bit different because while useful, they do not tell us about the external world. They do, however, work together with science to provide us with knowledge.