The Australian philosopher Michael Devitt (1938-) makes an empiricist point about necessity in science. He accepts that scientists discovered that water is H₂O. However, scientists didn’t also discover “that [water] necessarily is H₂O”. In other words, “necessity is not an empirical discovery”. Or, in yet other words, “we do not simply observe the necessity of water being H₂O”.
Indeed what would such an observation of necessity be like even if conceivable? Where does this necessity come from? What does it add to the scientific or any picture? And, semantically, what does it mean to claim that “water is necessarily H₂O”?
All that said, not even empiricists believe that every entity of science can be observed or that science is literally all about observation. So Devitt adds:
“We do not observe most scientific facts: we discover them with the help of a lot of theory.”
So, at the very least, an empiricist may also add:
Theory helps us get at the empirical facts.
Yet not even scientific theory can help us discover the supposedly essential or necessary features of a given scientific fact, object or event. That because these modal terms are not in themselves scientific — they are philosophical and/or logical.
It’s an interesting to note that after discussing analyticity and its relation to the a priori, Michael Devitt says that the American philosopher Laurence BonJour (whom he classes as a “neo-rationalist”)
“has no more faith in attempted explanations [of the a priori] in terms of analyticity than I have and gives an excellent critique of their failings”.
In a sense, Devitt is right — and a philosopher like W.V.O Quine would have agreed with him. That is, in the first half of the 20th century analyticity was deemed to be the key to the a priori or at least to our understanding of it. (That’s one reason why Quine spent a lot of time on analyticity in his ‘Two Dogmas of empiricism’.) That said, it still seems that Laurence BonJour doesn’t need — or even want — analyticity to demonstrate his rationalism (or apriorism). He doesn’t care if analyticity “makes the a priori palatable to the modern mind”.
So why did analyticity become “palatable to the modern mind” in the first place?
It did so because it treated the a priori (as well as necessity) as primarily — or indeed only — a linguistic matter. Clearly it’s not only — or at all - a linguistic matter to BonJour himself. Synonymy of terms (or concepts) doesn’t matter to BonJour. What matters is what BonJour calls “rational insight”. (As it did to Edmund Husserl with his essences and meanings — see here.) And that has nothing much — or at all — to do with language, analytic statements or analyticity itself.
Our Rational Insight into the Necessary Features of Nature
So what does BonJour mean by “rational insight”?
In terms of a priori justification, rational insight
“occurs when the mind directly or intuitively sees or grasps or apprehends… a necessary fact about the nature or structure of reality”.
Necessity is not, then, a question of language, the synonymy of terms and all the rest. It’s about the nature (or structure) of reality itself.
Instead of talking about words, concepts or meanings, BonJour talks about “properties” or the “properties of the world”. Thus we must immediately ask how the mind can grasp a priori (or by rational insight) anything about the world.
Of course rationalists — from Plato to Thomas Nagel in our own time (see here) - have already told us about the (necessary) features or properties of the world. It was just the case that they didn’t need observations of the world (or experience generally) to tell us about them. (In Kant’s case, the necessary features — or properties - of the mind were the very “conditions of experience” of the world.)
But what does all this highfalutin stuff actually mean?
We all know what it means in the case of Plato, Kant and others. But what about Laurence BonJour in our own day? As Michael Devitt puts it:
“[O]ur problem of explaining the a priori becomes that of explaining rational insight.”
What does BonJour offer that Plato, Kant and the rest didn’t offer? Perhaps he doesn’t claim to offer us anything new. Or perhaps only his language (or his technical terms) are new. (This may be yet another case of Jacques Derrida’s “sign-substitutions”.)
I’ve asked all these questions about rational insight while already knowing that BonJour himself says that “we do not presently have anything close” to an explanation of it. Yet perhaps that in itself is no reason to reject rational insight out-of-hand — and it certainly isn’t a denial of its reality.
So perhaps rational insight is unanalysable or primitive in nature. And, if that’s the case, then this doesn’t — automatically — mean that it is “objectionably mysterious, perhaps even somehow occult”. Instead of being mysterious (or even occult) we can see rational insight as being “fundamental and irreducible” instead. And, if we accept that, then it may be “in no way puzzling or especially in need of further explanation” (BonJour, in Devitt).
That last phrase, however, is a little hard to swallow —i.e., something’s being in no need of further explanation. (Many such things have existed — and still exist — in both philosophy and science.) Devitt doesn’t like this. He seems to suggest that BonJour’s happy acceptance of the inexplicability of rational insight is brought about by his fear of the “intellectual suicide” which we’ll effectively (or seemingly) commit if we throw the a priori overboard — as many (or all?) naturalists have attempted to do.
Yet philosophical naturalists needn’t be so hard on BonJour.
That warning can be explained through a similar case.
Many people think that eliminativists — or “reductionists” — in the philosophy of mind reject things that are (as it were) staring them in the face — whether that’s consciousness, mind or qualia. The same is true with rational insight. We all have — or use — it. So just go ahead and carry out an example of modus ponens and then you’ll find it hard to reject BonJour and embrace Devitt’s epistemic eliminativism.
More technically, what none of us can reject is the “the intuitive or phenomenological appearances” (BonJour, in Devitt) of rational insight. There is (as Thomas Nagel put it, if about something else) “something it is like” to have rational insight. That something it is like is, perhaps, all we need to see where BonJour is coming from. Indeed these “appearances” must surely prove to be “extremely obvious and compelling” to all but the intellectually blind. Thus to deny rational insight is like denying the pain in one’s tooth.
Incidentally, just as what it is like to experience pain is hard to explain, so BonJour accepts rational insight “even if we can’t explain it”. That’s primarily because even though we can’t explain it; we can still know it. And that, to BonJour, is enough.
Having provisionally accepted BonJour on all the above, it can now be argued that it’s not the phenomenological reality of rational insight (or its what-it-is-likeness) that’s the problem: it’s BonJour’s long jump from there to “the necessary character of reality” (BonJour, in Devitt). We can accept everything about the phenomenology in the case of logical truth or modus ponens (though Devitt doesn’t seem to). However, this stuff about the necessary character of reality… that’s a jump if ever there was one.
Devitt himself says that “[n]othing in the phenomenology supports” this stuff about nature (or reality) and its necessary character. However, traditionally it was only the a priori (or rational insight) which (as it were) gave us anything necessary about nature (or reality). So BonJour isn’t claiming anything new here. Indeed he’s a soi-disant “old-fashioned rationalist” — so perhaps we shouldn’t expect anything too new from him (i.e., other than terminology).
Again, we can ask the following question:
What non-experiential link to nature (or reality) could support insights into its necessary character?
This is the clash made by the supposed link between non-experiential rational insight and… well, the empirical world.
A Priori Logic?
Despite what’s just been said, Devitt’s radical — or even eliminativist — position towards the a priori isn’t only aimed at this strange link between rational insight and the necessary features of nature/reality— it’s also aimed at the ostensible a priori nature of logic itself. Devitt concludes with what he calls a “nice abduction”. He writes:
“[O]ur knowledge of mathematics, logic, and the like cannot be explained a priori; an empirical explanation of it is the best.”
Yet just as it was argued that BonJour’s apriorism (or rationalism) is not entirely new, so Devitt’s extreme empiricism regarding the a priori in logic is not entirely new either. More clearly, Devitt’s words above could almost have been written by J.S. Mill (1806–1873) over a 150 years ago (see here). Yet despite Mill, that other great empiricist — David Hume (1711–1776) — happily accepted the a priori and necessary status of both logic and mathematics. Of course, there’s also some dispute about Hume’s precise position on logic and maths too (see here).
BonJour, Laurence, ‘Is There a Priori Knowledge?’ (2005)
Devitt, Michael, ‘There is no a Priori’ (2005)