All, I apologize for the trouble finding the reading. It’s posted over there on the right.
Today we encountered the philosophy of science of W. V. O. Quine. Karl Popper famously argues that science is deductive, rather than inductive. Faced with the same problem of induction, plus two additional problems, Quine responds very differently. Quine considers the paradox of the black ravens, and the grue paradox.
The raven paradox goes like this. If scientists learn by induction, individual observations lead them to suppose a general law, of the form “All ravens are black”. However, “All ravens are black” is logically equivalent to “All non-Black things are non-Ravens”. But if you set out to confirm this, it’s much easier. The computer you’re reading this on is a non-Black, non-Raven! Now it seems that science can be done from the armchair.
The grue/bleen paradox gets its start from this question: How do you know that things are blue? You might say, you know because you have observed them in the past, and they were blue or green then. But all your observations would have been exactly the same if they were bleen – bleen being the property of looking like blue things today and green things tomorrow. (In fact, as we heard in class, babies’ eyes may have this property of looking blue one day, and some other colour the next.) The problem is that all your inductive evidence for calling something blue is equally good evidence for calling that thing bleen.
Both of these are paradoxes for anyone who thinks that we can learn by induction, but Quine is not bothered by them. For him, science and philosophy are the same thing. He says that grue and bleen, not-black and not-raven are not projectible, meaning that we do not carve the world up in these terms. That is because science and philosophy are the same thing, so there is no way to escape from science in order to critique it.
Dividing the world up into kinds is a very basic way of thinking, one we share with other animals. Our kind-discerning ability is probably an evolved behaviour. But we have the capacity to refine our theories (as we do with colours) to speak about the precise wavelengths of light that make them up. Referring to those wavelengths is better than referring to colour because it is clearer, and thus more scientific. As science progresses, Quine thinks, we will understand the world better and better – and speak less and less about kinds.