Moving on to discuss Chapter 2 of Catarina Dutilh Novaes’s The Dialogical Roots of Deduction …
CDN has argued in her opening chapter that “deduction remains a puzzling phenomenon. While a number of accounts have been proposed, none of them is entirely satisfactory.” So how to proceed? In §2.1, she proposes to adopt a “more encompassing perspective” than usual, using a wider range of “methodological approaches”. But what, more specifically, does that come to? She writes “the key idea of the project … was to go back to the roots of deduction. It is obviously inspired by Quine’s classic The Roots of Reference (Quine, 1974).”
Now, in principle, that is just fine by me: I’m a fan of Quine’s (underrated?) book, and I’d love to see a broadly comparable project to his, now focused on questions about deduction. But I’m not sure that’s really what we are going to get, as CDN immediately goes on to say that the way she “conceive[s] of the roots in question is broader in scope than Quine”, to the point where we are going to need “sustained engagement with the empirical literature in psychology, cognitive science, and education sciences”, and also “analysis of historical texts … but combined with a broader historical perspective taking into account developments outside philosophy”. I’m open to persuasion that casting the methodological net so very widely will give us in the end a coherently illuminating story: but the project certainly isn’t sounding very like Quine’s sharply focused project.
In fact, §2.2 is titled “The Different Roots of Reference”, and CDN says more about the variety of considerations she wants to bring to bear on her topic. I continue to have a question though — one I had already about Chapter 1 — of what exactly the topic is. She talks of ‘deductive reasoning’. And sometimes this seems to mean elaborated passages of multi-step reasoning (the sort of thing that’s indeed a bit of an acquired taste). For example, she writes “deductive reasoning emerged as a cognitive technology (though arguably, it remains restricted to circles of specialists), in a way similar to literacy.” If we are focusing on that — the sort of thing that, paradigmatically, mathematicians go on for — we’d all agree that there are will be an interesting “historical question: which cultural processes gave rise to the emergence of deductive reasoning [in that sense]” and an “ontogenetic question: how do deductive reasoning skills arise in a given individual?”. And again, when CDN writes “it is not clear that deductive reasoning abilities in fact confer survival advantages on those individuals”, maybe that case is indeed arguable for reasoning-as-extended-passages-of-argument.
But what about, say, the ability to form disjunctive beliefs, and then use such a belief in a step of disjunctive syllogism? What about, say, the ability to form conditional beliefs (in formulating plans), and then use such a belief in a step of modus ponens when we come to believe the antecedent? Are these cultural variables? Some might suppose, I guess, that a culturally contingent practice of extended deductive reasoning has its roots (to borrow a word!) in capactities for simple-minded deductive reasoning which are not so variable. (And the fact that there are some relatively simple deductive tasks we are not very good at — as the Wason test reminds us! — is no reason for thinking that being good at the ones we are good at doesn’t confer evolutionary advantage!) CDN writes that she is going to “survey the main findings on how deductive reasoning skills emerge and develop in individuals, drawing in particular from the literature on the psychology of reasoning and on mathematics education”. That may indeed be an interesting project — but we’ll have to see what it can tell us about deductive inference in general, as opposed more extended passages of reasoning in particular.
In §2.3, CDN links the project of looking for “roots” of deduction with the claim that the concept of deduction has significantly changed over time. Which again rather points up the non-Quinean aspects of her notion of “roots”. And this gets me wondering about the variety of philosophical enquiries that might be deemed illuminating enquiries into “roots” in some broad sense (and CDN’s usage is nothing if not broad). So before going on to comment on §2.4, where CDN first sketches her dialogical approach, I’m minded — just to get my own ideas straighter — to pause over this, and say something in my next post about the variety of enquiries into “roots” we find in books I greatly admire by Bennett, Hacking and Craig, as well as by Quine.
To be continued.