I am working my way through The Stuff of Thought and I find a statement that I have read many variations of: "Extraordinary claims...deserve extraordinary evidence."
What does that even mean?
"Think this through with me, let me know your mind."
From a scientific point of view it it first seemed to me that the alleged extraordinary nature of a claim is it seems to me subjective and irrelevant. There are claims and there is evidence. Now as I reflect on Pinker's use of the phrase, it occurs to me that I need to make a distinction, which saves the statement for some purposes although not necessarily for Pinker's. This is a blog. I haven't read much beyond that statement. It is a rendition of what I am thinking as I read, having put the book down for a bit.
Pinker at the moment (well actually sometime in the past, but reading gives me the impression that what he writes is being said contemporaneously with my reading) is criticizing a particular theory. Now a theory can be refuted or ignored. It can be refuted by showing that the claims and predictions it makes don't fit with actual world. It can also be ignored. It simply may not interest us. This latter is extremely important in my view and it leads to an analysis of what we are doing when we think and when we speak and write about stuff and what causes us to react to a claim in a fashion that makes us demand "extraordinary evidence."
One thing it might reveal (putting emotional stuff aside) is being wed to an inductivist view of the world. It is criticizing a theory on the basis of what gave rise to the theory. It assumes there is a sort of inductivist method by which theories are properly constructed out of individual pieces of evidence and if that method is not followed the theory is defective. In particular it assumes that particular kind of theories require particular kinds of evidence, and if they are formed without such types of evidence then the theory is defective.
Another thing to note is that any claim of fact which is not predicted or which contradicts the predictions of the accepted theory or paradigm is almost by definition extraordinary. If a person makes a claim as to having observed such a fact how is it possible to demand evidence of that fact, which doesn't come down to the person merely saying I saw it? We ask that it be reproducible perhaps or look for similar anomalies elsewhere. But that's just run of the mill science. It's theory, observation, test, etc etc...
Anyway the theory that Pinker criticizes is one that says that we have approximately 50,000 innate concepts wired into us. Maybe the problem is that such a statement may not be testable. But certainly tests of some sort can be devised. For instance by combining that statement with other theories or accepted facts about the brain, we might determine that for the brain to hold an innate concept it requires x number of neurons linked in a certain way. 50,000 innate concepts would then predict 50,000 times this number of neurons and particular links. If that number is bigger than the observed number in the human brain then it would seem to have been falsified.
Strangely with the brain being what it is I don't necessarily see 50,000 innate concepts being an extraordinary claim. It may be false, but really it's just a claim. Can we test it? If not well just let it go. If yes well do we want to? If so then test it. If not, don't. What's extraordinary here?