Inferring and Explaining

45 t 2 . The uniquely human ability to acquire and use a natural language is a gift from God. Chomsky and Gould would undoubtedly invert t 0 and t 1 . Joyclynn was forced in the exam to commit herself on whether t 0 was better than t 1 , and as I remember, she preferred t 0 . But she dramatically disagreed with her teacher and ranked the three hypotheses as follows: t 2 . The uniquely human ability to acquire and use a natural language is a gift from God. t 0 . The origin of language is explained through the theory of natural selection. t 1 . Natural selection produced larger, and more neurally dense, human brains. It was a “side consequence” that these brains gave us such remarkable language abilities. Disagreements What in theworld dowe do about passionate, but reasoned, disagreement? Stephen Jay Gould and NoamChomsky were two of the most important scientists of the latter twentieth century. Steven Pinker and Paul Bloom are stars of the twenty- frst century. Based just on their credentials, it’s impossible to take sides. Joyclynn Potter is no natural scientist, but she’s a very smart and thoughtful woman. What are we to make of the obvious fact that very intelligent and very hon- orable people disagree about where the evidence points? Some might argue that all this shows a fatal faw in the whole inference-to-the-best- explanation approach to evidence. How can I continue to argue—as I already have and intend to even more vigorously in a later chapter—that we are skilled explainers when equally smart and committed people so dis- agree as to what the best explanation really is? Te short answer is that this is simply the nature of evidence. Lots of times, it points in a clear direction, and we can expect some- thing like intersubjective agreement. In these easy cases, which I believe constitute the vast majority of times when we consciously evalu- ate evidence, inference to the best explanation brings us close to the standard of knowledge we developed in chapter 3. Te evidence for the hypothesis that smoking is a causal factor in lung cancer is so strong that we don’t simply say that the evidence points in that direction; we rather say that we now know that smoking causes lung cancer. We’re probably not at that degree of certainty about what happened at the record hop nor do we yet possess the full story about the origin of natural language. Still, we possess lots of rel- evant evidence. Inference to the best explana- tion helps us reach our personal evaluation of the evidence and hopefully helps us understand the reasoning of those who see things difer- ently. None of us—not our greatest scientists, Supreme Court justices, nor just the smart people we interact with regularly—possess the so-called God’s-eye view, which would allow the simple “perception” of the truth. Since we don’t, the best we can do is rely on evidence to help point us in the direction of the truth. And as the history of science or contemporary debates in jurisprudence and cognitive science tell us, we simply have to expect a certain amount of reasoned disagreement. InferenCe to the Best exPlanatIon