In the course of a normal day, we may show a receipt as proof that we've paid for a service or be asked to show ID as proof of our age or identity. But ask a climate scientist or evolutionary biologist to "prove" that humans contribute to global warming or that Darwin was right all along and you may get an eye roll. Of course, the evidence for these widely accepted scientific beliefs is overwhelming, but most scientists will tell you that they aren't in the business of "proving" anything.
Here's why: Proofs are considered final. Evolutionary psychologist Satoshi Kanazawa argues that "proofs exist only in mathematics and logic" (some might add whiskey to that list), but not in science. In mathematics, once a proposition is proven, it becomes a theorem. (The square of the hypotenuse of a right triangle will always be equal to the sum of the squares of the other two sides. There's no gray area, and there's no need for Pythagoras to prove it again.)
Science, on the other hand, seeks to continually expand our understanding of the world, based on the principle that "any idea, no matter how widely accepted today, could be overturned tomorrow if the evidence warranted it" [source: University of California Museum of Paleontology]. Based on that possibility, nothing in science is considered proven.
Where does all that scientific evidence come from? Read on to find out.