Saturday, March 26, 2011

Mediaeval and Modern Logics I

Nevertheless, it is still a medieval world of thought we meet in Duns Scotus’ oeuvre, expressed with the help of scholastic tools, invented and elaborated on in Latin based semantics and logic. However, this world of thought does not depend essentially on these scholastic tools. We may pile up a list of famous names from modern logic and philosophy who have established theories Duns Scotus’ philosophy is definitely in need of: Cantor – Frege, Russell and Beth – Lewis, Kanger and Hintikka – Kripke and Plantinga – Wittgenstein, Ryle and Austin. We can also compose a list of crucial theories: the theory of sets and, in particular, the theory of infinite sets (Cantor), the theory of logical connectives and the logic of quantifiers (Frege, Beth), the logic of relation and identity (Russell, Whitehead). In general, modern standard logic is an excellent tool to translate, to extrapolate and to defend Scotian theories in combination with the ‘linguistic turn’ (Wittgenstein, Ryle, Austin). Moreover, modal logic (Lewis, Kanger, Hintikka) and the ontology of possible worlds (Kripke, Plantinga) are crucial theories to discuss adequately Duns Scotus’ ontology and philosophical and theological doctrines of God.


-Antoine Vos, The Philosophy of John Duns Scotus, 8.

I really wish that Vos made clear somewhere in his book exactly which theories by these guys Scotus' philosophy is "definitely in need of." He doesn't, so far as I recall, and so I'm left very dubious. In fact I've long suspected that set theory and its use in the foundation of modern logic has had an almost completely pernicious effect on modern philosophy, emphatically including the so-called "linguistic turn" and possible world theorizing. The common element in all of these seems to me to be a systematic conflating of the logical with the ontological order, to the detriment of the latter. When contemporary philosophy lays down at its very beginning a set of premises making it difficult if not impossible to distinguish between ens realis and ens rationis, it guarantees a failed metaphysics.

My own opinion is that, if mediaeval philosophy can take useful supplements from modern thought, these are more likely to come through the phenomenological than through the linguistic-analytical traditions. (This is what St Edith Stein tried to do, though I haven't studied her very thoroughly yet and can't say how successful she was.) One has to acknowledge, though, that philosophers today attempting to "encounter" mediaeval philosophy through the lens of either tradition are much more likely to spoil and ruin it than to enhance it.

9 comments:

Lee Faber said...

That's a rather long list of names. In what sense would it still be scotist once it had been "corrected". Plus, I hate the word "scotian".

Leo Carton Mollica said...
This comment has been removed by the author.
Leo Carton Mollica said...

"Moreover, modal logic (Lewis, Kanger, Hintikka) and the ontology of possible worlds (Kripke, Plantinga) are crucial theories to discuss adequately Duns Scotus’ ontology and philosophical and theological doctrines of God."

Funnily enough, I seem to recall Scotus discussing his theology perfectly well without recourse to S5. Just because you are incapable of describing modality without bringing in an infinite array "possible worlds," oh narrow-minded analytic philosopher, does not mean that nobody can. Sheesh.

Thanks, though, for the passage and insightful commentary.

Michael Sullivan said...

It's hard not to agree with you, Leo. Vos' book is valuable in a number of respects, but the writing is rather, ah, histrionic, and there are quite a number of offhand unsubstantiated statements like this.

Lukas Novak said...

This is a very interesting topic. In my opinion, contemporary philosophy is in bad need of metaphysical thought; and the best metaphysics there ever was is the scholastic one. But in my opinion if there is to be any synthesis of contemporary thought with scholasticism, it can only be with the analytic branch of the contemporary thought. Why? First, because the "continental" tradition has (leaving aside some minor exceptions like the minority realist phenomenology) rejected the very foundations on which any true metaphysics can be built. The contemporary continental tradition is still haunted by the ghost of Kant. Second, continental tradition has abandoned the only viable instrument for metaphysical enquiry, which is logic, and substitued various ersatz-methods instead, like phenomenology, or rhetoric, or poetry. Third, because the analytic tradition, not having abandoned logic, has been under its beneficiary influence for some hundred years now and so has been at least in some of its strands cured from its original antimetaphysical affect.

In my opinion there are some very useful things in modern logic and analytical philosophy, and some less so. For example, I regard the Fregean "function-theoretic" analysis of predication as philosophically deadly, the more so that it doesn't seem to be based on any arguments at all, but merely on the pragmatic consideration that it "works". But as F. Sommers has shown, term logic can work equally well. On the other hand, the apparatus of possible worlds is IMHO an excellent tool for logical analysis of modalities, and I have used it innumerable times to analyse and clarify Scotus's and other schlastics' argumentation. One only has to remember that it is just a logical apparatus, which as such is in need of interpretation as regards its "ontological import"; and the interpretation is not encoded in the logic itsef but must be supplied by genuine metaphysics (for example, a Scotistic one). In a sense, Scotus _was_ the discoverer of S5; many of his inferences that remain merely intuitively valid in his own setting, appeac crystal clear when translated into the language of possible worlds.

As regards phenomenology: I don't think that that project is flawed in itsef. It is just a method. The problem is when one starts to believe (like Heidegger) that one can distile any metaphysics from their observations of phenomena as phenomena, without "speculation", that is, logical inference from the empirical to the non-empirical. So phenomenology can be _supplemented_ with genuine metaphysics, but it cannot substitute it. Besides, the majority of phenomenologists combines phenomenological method with transcendental-idealist metaphysics. Such an amalgam is, IMHO, incompatible with any genuine metaphysics.

Michael Sullivan said...

Lukas, thanks for your very stimulating remarks. I agree with you about the continentals in general, for most of whom I have very little patience; I had in mind Husserl and Husserlians specifically. I don't think anyone could claim that Husserl abandoned logic! But I also emphatically agree with you that phenomenology has to be supplemented by metaphysics. And I have little use for Heidegger and his spawn, postmodernists, post-postmodernists, or whatever the fad is these days.

I also agree with you about Fred Sommers. I had a graduate course under him some years ago and was convinced by the validity of his approach, though I haven't followed up on it much since then. (Brandon Watson at Siris had a series of posts on using Sommers notation last year which gave a good introduction to the subject, if anyone is interested.)

On the other hand, the apparatus of possible worlds is IMHO an excellent tool for logical analysis of modalities, and I have used it innumerable times to analyse and clarify Scotus's and other schlastics' argumentation. One only has to remember that it is just a logical apparatus, which as such is in need of interpretation as regards its "ontological import"; and the interpretation is not encoded in the logic itsef but must be supplied by genuine metaphysics (for example, a Scotistic one). In a sense, Scotus _was_ the discoverer of S5; many of his inferences that remain merely intuitively valid in his own setting, appeac crystal clear when translated into the language of possible worlds.

This is very interesting and I'd appreciate hearing more about it. Do you have any examples? In my experience whenever e.g. Thomists use possible-worlds talk it comes out sounding hopelessly muddled to me.

AT said...

I can understand your doubts. But what Vos is saying here, is - in my opinion - that Scotus' philosophy can be illuminated, underpinned and in some ways even be proved by contemporary logical and semantical theories.
That is, of course, quite a claim. Vos however knows what he is talking about. His Ph.D.thesis (unfortunately only available in Dutch under the title 'Kennis en noodzakelijkheid')explores these claims with the help of the semantics of possible worlds, modal logic and so on. In this book he claims that Scotus' philosophy - and especially his notion of synchronic contingency - is the key to a consistent doctrine of God.
Is that a conflation of logic and ontology? It is, but what's the problem? Take for example the law of non-contradiction. Anyone who is working in science or technology, takes this law ontologically for granted. Otherwise, you couldn't do your work. So , what is the exact problem with the conflation of logic and ontology?

Michael Sullivan said...

AT,

I don't say categorically that Vos is wrong. It's just that he doesn't elaborate in the present book, leaving the reader to guess at his meaning.

Lukáš Novák said...

I apologise that I was unable to reply earlier. Regarding Husserl - well, he started his philosophical project just like Frege, as a quest for re-achieving the objectivity of logic. But soon he came to believe that true objectivity can only be achieved on the level of pure phenomena and therefore excluded "speculation" - that is, argumentation, from his method. IMHO his mature, transcendental-idealist thought is incompatible with metaphysics - as his "objectivity" is always a subjectivised one, "objective" for him is what is _perceived_ as objective - and this is what we should swallow as the solution of the epistemological problem.

Regarding the utility of S5 in interpreting Scotus - for example, the entire line of argumentation in De primo principio toward the necessary existence of the first cause can be, IMHO, set forth very clearly by means of the possible world apparatus. It is clear, for example, that the assumed modality must be the broad logical possibility (coextensive with metaphysical possibility for Scotus), and not some "causal possibility" or so as e.g. R. Cross would like to read him. However, to argue this out properly would require much more space - perhaps I will write some paper on the topic some day... :-)