On W.V.O. Quine's "Epistemology Naturalized" (1969), featuring Mark, Wes, and Seth.
What justifies scientific theory? The classical epistemological project found in figures like Descartes and Locke seeks to find basic, indubitable premises that serve to ground the rest of our theorizing. Quine begins by considering Hume's attempt to do this by claiming that all we ever experience are sense impressions, so anything else we know must be based on that. Rudolf Carnap took Hume very seriously and tried to actually reduce the meanings of complex propositions to their base sensory components, and Quine's goal in this essay is to show why this does not in any way work. In fact, Quine wants to reverse the order by which philosophers base science on epistemology to instead propose a less problematic way of pursuing epistemology: through psychology, i.e. science. Making epistemology part of natural science is what "naturalizing" it amounts to.
Quine relates the question of theory vs. observation that we've considered in looking at philosophers of science such as Popper, Kuhn, and Lakatos to the pre-scientific context. According to a verificationist like Carnap, the meaning of at least certain basic sentences, which philosophers call observation sentences, is cashed out in terms of what sensory situations they relate to. So we tend to think that "it is raining" is certainly related to a person being in a situation where they're perceiving rain happening right now in their vicinity. If the sentence is being used literally and observationally, i.e. in its "normal" usage (as opposed to its use in a play, or as metaphor, etc.), then the sentence literally means that perception... or we should better say "perceptual situation," because we don't want to have to take into account the minor differences that different perceivers might have. The point is that anyone with the relevant senses in that situation, on hearing that sentence and understanding it to refer to that situation would both then know the meaning of "it is raining" and (importantly distinct for Quine) be able to confirm the truth of that sentence.
All other sentences/bits of knowledge according to an empiricist ultimately rely on these basic sentences. But as we've discussed in other episodes (e.g. Sellars, Hegel), the idea of a "theory-free" perception like this that everything else could be based on simply doesn't work. There are several basic assumptions about physical objects, time, and space that are already assumed by talk of rain happening now. Kant's solution to this was to say that those basic categories are part of the human makeup and are necessary to think at all. Quine doesn't want to go so far as that; instead, he says that knowing a language is knowing how to use words in their appropriate context, and this involves a mass of theory. To say what an individual observation sentence means, we'd have to also characterize the rest of the theory. Two speakers of different languages could have observation sentences of the same event (the occurrence of rain, for instance), and these sentences would actually mean different things, because of their different theoretical contexts.
To explain this, he uses the image of two speakers who don't understand each others' languages trying to come up with a translation. If I see the person uttering some sentence "bango!" in the presence of rain, I might assume that word means rain (or rather, the one-word sentence means "it's raining."). I could then test it by pointing at other phenomena (e.g. snow, sunlight) and saying "bango?" and seeing if the person assents. So it seems like this is a route for translation, that "it is raining" and "bango" both mean (in the verificationist's sense) the phenomena of it raining now. But not so fast, Quine says. What if my foreigner thinks of rain as a persisting entity, as a rain god showing his liquid essence, whereas I have a meteorological view of the matter. According to Quine, our three sentences don't actually mean the same thing due to their different theoretical assumptions. Well, perhaps this difference could be tested for, if I were able to ask "is this the same rain as before?" For me, the answer would be no, but for the foreigner, yes (it's the same liquid essence). Ah, but what if there's a additional difference in linguistic convention, such that while I say "it's raining," the foreigner's remark would better be translated as "he appears as rain"? So if I ask, "is that the same rain?" the foreigner understands this as "is this the same appearance as rain?" Both of us answer no, because for me, it's a different cloudburst, but for the foreigner, it's a different occasion on which the singular wet god appeared. We're using the sentences in the same way, in the same perceptual circumstances, yet because of the interlocking nature of our various beliefs and linguistic meanings, we don't actually mean the same thing, and we can't even figure this out. Quine calls this indeterminacy of translation: an experience underdetermines its observational description. Quine even conjectures that two such descriptions might even contradict each other, yet each accurately describes the perceptual situation. (Though this claim is actually pretty wild, and doesn't seem possible to sketch an example of; in my example, the two speakers are just talking past each other by employing different conceptual schemes, not actually in contradiction.)
To get clearer on this, you may want to review our past episodes on Carnap and Quine, which provide more information on Carnap's "Aufbau" project that Quine is reacting to here and also gives Quine's argument specifically against the idea of synonymy, i.e. two expressions' having the same meaning, which is obviously an essential component for Carnap who's trying to reduce complex expressions to simpler ones that are in some sense synonymous with them. We also refer to Russell's reduction of mathematics to logic and set theory and Gödel 's demonstration of the incompleteness of any axiomatic system (like Russell's attempt).
Quine's account does not so much debate with positions like Lakatos' so much as complement them. Quine agrees like these modern philosophers of science that scientific advancement is not a matter of deductive certainty, because there's no theory-free way to interpret an observation made on an experiment. Like Lakatos and Kuhn, Quine would agree that in the face of an experimental result, there are choices to make about which parts of one's web of theory to change. However, he described Kuhn's position as an "over-reaction" for reasons that he doesn't go into. My sense is that Quine is interested here in the technicalities of meaning, not in actual scientific practice. The fact that in theory two contradictory observation sentences could both be true of the same observation doesn't mean that this actually happens in scientific practice, because the various competing scientific theories are not so profoundly different as the competing metaphysics included in my rain example. But one can also see how thinkers like Kuhn and Feyerabend might appropriate Quine's argument to support radical differences in conceptual schemes, and this is exactly why Donald Davidson responded to this by arguing that any two schemes have to be actually translatable into each other for them to count as language at all.
Buy the book containing this essay, Ontological Relativity and Other Essays, or read the essay online. Two secondary sources we recommend for this are Gary Kemp's Quine: A Guide to the Perplexed and Peter Hylton's Quine. Both of these authors worked on the Stanford Encyclopedia entry on Quine.
Image by Genevieve Arnold. Audio editing by Tyler Hislop.
Continue listening on part two.