cient strategy by looking as hard as we can for cardinals that are not red. The longer we look and the more creative we can be in trying to find those non-red cardinals—assuming we don’t find any— the stronger our original hypothesis becomes. Popper’s view gives us a more efficient strategy, and rather than just piling up positive examples, we strengthen our hypothesis if we attempt vari- ous ways of showing that the hypothesis is false, but fail to do so. The method Popper outlines pro- vides a different way of thinking about the logic of scientific inquiry and how we might go about examining our scientific hypotheses. Testability and Falsifiability One important aspect of scientific claims that Popper emphasizes is that such claims must be testable and falsifiable in order to be scientific. A claim is testable if we can come up with a way of seeing if it is true or not. We can test, for instance, that pure water will freeze at 0 8 Celsius; we can’t, currently, test the claim that pure water in another galaxy tastes like root beer. We have no way to develop a method of determining the truth or falsity of the second claim. A claim is also said to be falsifiable, in that it could turn out actually to be false, and we know how that might be shown. For instance, “There are no wild kangaroos in Georgia” is a falsifiable claim; if we went to Georgia and found some wild kangaroos, we would have shown it to be false. But what if someone claimed that there are unicorns in North Carolina, but that they are invisible? Could we ever show such a thing to be false? It would seem to be the kind of claim that cannot be shown to be false, and so is said to be unfalsifiable. Most scientists operate with the assumption that any scientific hypothesis must be test- able and must be the kind of claim that we could show to be false. So if a claim turns out not to be testable—or if a claim turns out to be one that could never be shown to be false— the claim isn’t really scientific. For instance, astrologers often make predictions; but if a Laurence Mouton/Photolibrary Rather than looking to confirm our hypothesis, Karl Popper suggests that we should be looking to disconfirm our hypothesis.

CHAPTER 5 Section 5.3 Scientific Arguments claim is something that can’t be shown to be false, such as “you will meet someone interesting,” then it isn’t a scientific prediction. Or, if a claim can’t really be tested, it also isn’t scientific. Imag- ine I give you my lucky rabbit’s foot. How could we test its success in bringing you luck? Could we ever show that the rabbit’s foot caused your good luck, or that not having it caused your bad luck? Scientists do their best to avoid making claims that are untestable, as well as claims that can never be shown to be false. And, oddly enough, a scientific claim that always comes out to be true will not be a very interesting claim. (Scientists, of course, argue at some length about whether some claims are, in fact, falsifiable or testable.)