Skip to 0 minutes and 14 secondsOne last step here. Some hypotheses can't be falsified. Here's an alternative explanation for the fossils we find. According to this chap, Philip Henry Gosse, the initial observations about the fossils were mistaken. Gosse thinks the earth is between 5,000 and 10,000 years old. The apparent order of the fossil record was created by God, who made the fossil records look as they do for, well, mysterious reasons. By way of illustration, Gosse points out that paintings of Adam show him with a navel or belly button. Now, of course, there's no reason for Adam to have had a navel. For those of us born the regular way, it's where the umbilical cord attached. But Adam was not born the regular way.
Skip to 1 minute and 2 secondsNow, I'm a bit puzzled by Gosse's move here. Why not go for the simpler explanation that the people who painted Adam made a mistake. But putting that reservation aside for the moment, Gosse seems to have thought that Adam really did have a navel. And he explains that by saying this. Just as Adam had a navel, evidence of a gestation he never experienced, so also the Earth was created compete with evidence of a prehistoric past that never actually occurred. OK. What's the point of this, other than to go on a small detour through an entertaining bit of scientific and unscientific history. Well, you might think there are lots of things wrong with Gosse's hypothesis.
Skip to 1 minute and 47 secondsBut here, we're interested in only one, its status as a scientific hypothesis. And that turns on whether it could, in principle, be falsified. And it looks as though it can't be. It doesn't matter what we observe, what our tests show, how careful we are about the logic, Gosse will always be able to say, oh, God made things turn out like that. I'm still right. So whatever else we might think of his hypothesis, it's not scientific. And it's not scientific, because it's not falsifiable.
Science and falsification
Scientific hypothesis must be testable: it must be possible to show that they are mistaken.