Hello Poe,

Is this *anywhere close* to a decent account of the Medieval account of predication? If not, in what respect?

I've never heard of a medieval “identity theory of predication”, but would be surprised if any medieval logician allowed the shift from J1 to J2.

Assume the move from “T is a man” to “T is identical with Manhood” is valid. Stephen Harper is a man. Hence, Stephen Harper is identical with Manhood. Barack Obama is a man. Hence, Barack Obama is identical with Manhood. It's a truism that a universal must be strictly identical in each of its instances. Hence, Stephen Harper and Barack Obama are strictly identical to each other. [url=http://i.cbc.ca/1.1668575.1379079759!/httpImage/image.jpg_gen/derivatives/16x9_620/li-stephen-harper-620-rtr33.jpg]Stephen Harper[/url] and Barack Obama are not strictly identical to each other. Hence, Stephen Harper and Barack Obama are and are not strictly identical to each other. Therefore, the move from “T is a man” to “T is identical with Manhood” is not valid.[1][2]

Medieval logics had the notion of different modes of supposition. Supposition here is the reference that a certain kind of term has in the context of a proposition.[3]

In the article, a move from “John is a man” to “John is identical with a man" would at least yield two true propositions, because “a man” has the personal mode of supposition in both propositions. It refers to a particular or individual. In contrast, the move from “John is a man” to “John is identical with Manhood” yields a false proposition, because “Manhood” has the simple mode of supposition. It has to do with a kind.

Alternatively, it just confuses being a specific man with having the property of "being human" (or, perhaps, "being male" which has similar issues). In the first case above, the terms "John" and "a man" in "John is a man" and "John is identical with a man" are both singular terms referring to the same individual: John. In the latter case, "John" is a singular term but "Manhood" isn't. Either way, I think medieval logicians would have considered the move from J1 to J2 a simple mistake.

I know that post-Russell post-Frege a lot of core aspects of philosophy of logic were simply abandoned for a set of new as I understand it jejunely anti-traditional logical assumptions

I wouldn't say Fregean logic is jejune (or, for that matter, anti-traditional). Fregean logic lacks a theory of modes of supposition, but the move from “T is a man” to “T is identical to Man” is invalid in it anyway.

Out of curiosity, what do you have in mind when you write “a lot of core aspects of philosophy of logic were simply abandoned”?

[1]It's also worth noting that (If Stephen Harper is a man, then Stephen Harper is identical with Manhood) is a counterexample for the theorem the move would involve.
[2]The theory fails on Ockham's logic too, because on Ockhamism “Manhood” is just a concept. Stephen Harper is more than a concept.
[3]In Missing Modes of Supposition, Terence Parsons writes “the word 'supposition' is probably interchangeable with our word 'reference'”. I think some maintain that “suppositing” is unique because reference doesn't, for example, necessarily apply to “Man” in “Man is a species” (ie. If certain nominalists are right). I'm not too concerned about this technical dispute—if there is one—here.

Last edited by John West (10/12/2015 10:47 am)

The claim that the Law of Identity can't be found in Aristotle is a little odd too. It's true (I think) that he didn't expressly formulate it, but he seems pretty clearly to be relying on it here (scroll down to the first seven paragraphs of Part 4).

I've had author corrispondence on the post:

Rosa Lichtenstein wrote:

Dear Matthew,

Thank you for your communication, although I am somewhat baffled by the responses I have just read over at your Forum. Here is one, for example:

"I've never heard of a medieval 'identity theory of predication'"

Perhaps this individual needs to read, say, Buridan and Ockham, only more carefully?

I actually derived the name for this theory from the late Professor Geach (a noted authority on the history of logic, as I am sure you are aware), who, so it happens, taught me logic; he used this term in lectures I attended back in 1978. Here is the relevant part of an essay of his --  'History of the Corruptions of Logic' -- where he calls it the 'Two Name'/'Term Theory':

"Aristotle's fall into the two-term theory was only the beginning of a long degeneration. Aristotle never rejected the distinction between an expression's naming an object and an expression's being truly predicated of an object, though of course his theory committed him to saying that one and the same expression could stand now in one relation, now in the other. But it is a natural further step to identify naming with being predicable of and to declare explicitly that the two terms of a categorical [proposition -- RL] are two names. So we pass from the two-term theory to the two-name theory. This two-name theory is best known in England from John Stuart Mill's Logic; Mill explicitly calls terms 'names', and speaks of many-worded names when he means syntactically complex terms. And Mill's term 'denoting' simply embodies the fundamental confusion of the two-name theory between the relations of being a name of and being predicable of.

"Mill was not a very subtle or hard-working formal logician; his main interests lay elsewhere. The two-name theory has had a long history and much stronger representatives than Mill. It was the predominant theory of the Middle Ages, and was expounded by such great men as William of Ockham and Jean Buridan; though there was a minority party of logicians who insisted that naming and predicating were radically distinct, and this minority had the support of Aquinas.... The two-name theory is like the theory that planetary motion has to be reduced to uniform circular motion. Mill's version of the theory is like a crude astronomy in which each planet moves in a simple circular orbit around the Sun; its breakdown is manifest. By increasing the number of logical devices we get something like Copernicus' astronomy, which by assuming considerable complexity of circles would fit the facts with few notable discrepancies. But just as Kepler could sweep away this complexity at the price of introducing a more sophisticated geometrical construction -- an ellipse instead of a circle -- so we get a simpler and more powerful logical theory if we distinguish names and predicables from the outset.

"Let us briefly consider some of the special troubles of the two-name theory. If what is predicated has to be a name, we get one or other of two awkward consequences. We may find ourselves recognizing as names what by any decent standard are not names, like 'on the mat', 'going to the fair'. Or we may insist that a predicate-term be properly dressed as a noun-like phrase, that it be 'put into logical form', before we will recognize it as a term, or as a predicate at all. 'Brutus stabbed Caesar' clearly says, predicates, something about Brutus and also something about Caesar. A man who has good logical perceptions will see this directly from the meaning of the sentence. But a two-namer cannot officially recognize that a predication is there at all until he has before his eyes the appropriate pair of names, say, 'Brutus' and 'stabber of Caesar' or 'Caesar' and 'one stabbed by Brutus'. Of course, he then owes us an explanation of how such many-worded names as 'stabber of Caesar' and 'one stabbed by Brutus' may be formed from 'Brutus stabbed Caesar'....

"If a proposition consists of two names, it must also contain a linking element to hold them together; remember Plato's point that a mere string of names does not make up an intelligible bit of discourse. Two-name logicians in fact assign such a linking role to the grammatical copula, in English the verb 'is' or 'are'. This was a further departure from Aristotle, who held that a proposition may consist simply of two terms. (The verb 'applies to' in the schema 'A applies to B' was meant only to give a sentence a lecturer can pronounce, not to supply a link between 'A' and 'B'.) And so there arose many perplexities as to the import of the copula.

"For the two-name theory, the copula has to be a copula of identity. For, in its pure form, the two-name theory says that an affirmative proposition is true because the subject and predicate terms name one and the same thing: 'Socrates is a philosopher' is true because one of the individuals named by the common name 'philosopher' is also named by the proper name 'Socrates'. But it is easy to slide away from this position. On the two-name theory, the common name 'philosopher' is here used as [the] name of every philosopher. But if we express this carelessly in the form

The term 'philosopher' denotes all philosophers

then it is easy to slide over to the view that what 'philosopher' denotes ...is not any and every philosopher, but rather the class of all philosophers.

"By this slide the rake's progress of logic that I have described has reached its last and most degraded phase: the two-class theory of categoricals. The subject and predicate are now said to denote two classes. (The terms are also said to be two classes; for the writers who hold the two-class theory are mostly very neglectful indeed of the distinction between sign and thing signified.)...." [Geach (1972b), pp.51-53. Italic emphases in the original. There then follow several rather technical objections to this theory; anyone interested can now read these on-line, here.]

Geach, P. (1972a), Logic Matters (Blackwell).

Geach, P. (1972b), 'History Of The Corruptions Of Logic', in Geach (1972a), pp.44-61.

I quoted the above at length in an Essay you and others at that Forum seem not to have read (where the links I  have inserted can also be accessed):

http://www.anti-dialectics.co.uk/page%2003_01.htm

In that essay, I also reference Gyula Klima's work on Jean Buridan (and Klima, another noted expert, does use this term):

"As this example may already suggest, for Buridan the copula is a sign of identity: for him, an affirmative categorical proposition is true if and only if its terms refer to the same thing or things at the time connoted by its copula, as required by the quantity of the proposition.
"There are a number of things we should clarify in connection with this apparently simple claim, which expresses what historians of medieval logic dubbed the identity theory of predication." [Bold added.]

Klima, Gyula (No Date), 'The Essentialist Nominalism Of Jean Buridan'.

The above link should work if you directly access the Essay in question -- or paste this into your address line:

http://legacy.fordham.edu/gsas/phil/klima/FILES/BuridansEssentialism.pdf

Someone else at your Forum says that they think the 'Law of Identity' can be found in Aristotle's work -- I have covered this topic in more detail here:

http://www.anti-dialectics.co.uk/page%2004.htm#Note 1

http://www.anti-dialectics.co.uk/page%2004.htm#Dialectical-Inanities

[If you are using Internet Explorer 10 (or later), the above links won't work properly unless you switch to 'Compatibility View' (in the Tools Menu); for IE11 select 'Compatibility View Settings' and then add my site. I have no idea what will happen if you use the new Microsoft Edge.]

Where, among other things, I quote Aristotle's Metaphysics:

"Now 'why a thing is itself' is doubtless a meaningless inquiry; for the fact or the existence of the thing must already be evident (e.g. that the moon is eclipsed) but the fact that a thing is itself is the single formula and the single cause to all such questions as why the man is man, or the musical musical, unless one were to say that each thing is inseparable from itself; and its being one just meant this. This, however, is common to all things and is a short and easy way with the question." [Aristotle (1984e), p.1643; Book VII, Part 17.]

This seems rather dismissive of the aforementioned 'law', does it not?

I also consider several passages that have been used to argue for the opposite conclusion, such as the one alluded to by one of those who contributed to your Forum.

Finally, my intention in these essays isn't to attack Medieval Logic (for which I have great respect largely because of the influence of Peter Geach), but to attack Hegel and Dialectical Materialism. In which case, in that essay, I am not really interested in what Medieval Logicians might have to say about its arguments/conclusions, but at the use to which this theory was put by Hegel, Engels and Lenin. I also noted this at the top of the Essay:

"This is an elementary summary of some of Hegel's more important logical blunders; it has been written for those new to the subject, not experts. This isn't meant to be an academic exercise, so the many complications that logicians are aware of in this area have had to be ignored. I have posted four much more detailed and technical analyses of Hegel's many errors here, here, here and here...."

Again, the above links should work if you access the original essay:

http://www.anti-dialectics.co.uk/Outline_of_errors_Hegel_committed_01.htm

In which case, as I also noted, I have had to make sure my arguments aren't obscured by the sort of considerations one of your administrators (John West), for example, outlines. 

Anyway, several of the things baldy asserted at your Forum (by John West) are, as I am sure you must also know, highly controversial and are still being contested, and not just by Peter Geach. Once more, my aim isn't to stir up, or contribute to, endless academic debate (for goodness sake, logicians have been hammering away at this topic for millennia), but to make a political point to those who already accept Marxism, not those who don't.

Hope that helps -- let me know if I can assist you further.

Apologies, I am merely making two 'empty' posts so that my third post will be allowed to include links!

John, thank you for those comments. Here is an e-mail (slightly edited) I sent to another of your members (who apprised me of this thread), which appears not to have been posted:

Hi, XXXX (name removed), 

I notice that John West now alleges that what I have to say about the controversial things he alleges is "false", but he admits he hadn't even heard of the 'identity theory of predication' (a term well known to logicians, and for many years (see below), and not just those expert in medieval logic). By way of 'proof' he offers us an introductory text! 

Well, perhaps he should upgrade his knowledge a little by checking out more academically sound sources, such as this, for example: 

T Aho and M Yrjonsuuri, 'Late Medieval Logic', pp.11-77 of: The Development of Modern Logic (Oxford, 2009), edited by L Haaparanta. 

See also: Peter Geach's 'Form and Existence' in God and the Soul (Routledge, 1969), and P Symington, On Determining What There Is. The Identity of Ontological Categories in Aquinas, Scotus and Lowe (Walter de Gruyter, 2010), chapters One to Three -- both of whom refer to the 'identity theory of predication' (the latter on page 77, for instance; the former on page 43 -- indeed, Symington devotes a whole section to this 'theory' -- Chapter 3). 

As well as: S Sousedík, 'Toward a Thomistic Theory of Predication', pp.247-56 of: Lukáš Novák, Daniel D. Novotný, Prokop Sousedík, and David Svoboda, Metaphysics: Aristotelian, Scholastic, Analytic (Walter de Gruyter, 2012). 

And:  H Lagerlund,  Modal Syllogistics in the Middle Ages (E J Brill, 2000), Chapter 3 'Richard of Campsall'. 

Need I go on? There are many other works I could reference (that John seems not to have read, or perhaps even heard of) -- the idea, but not the term, even appears in standard histories of logic, such as that authored by William and Martha Kneale --, for example, in their discussion of Abelard's theory of the copula, pp.206-10, and that of William of Shyreswood, pp.248-50 -- The Development of Logic (Oxford, 1975) --, where the controversies I allege to have existed in the 'Middle Ages' (which apparently are 'false'!) are also highlighted (pp.198-297). 

Also check this out: 

http://maverickphilosopher.typepad.com/maverick_philosopher/2012/11/stanislav-sousediks-towards-a-thomistic-theory-of-predication.html 

The only point I wish to make, however, is that John's ideas are controversial (whatever he asserts to the contrary) -- even medieval logicians debated these issues endlessly -- and they are still being thrashed out by logicians --, as the above sources indicate. Now, I do not wish to take sides on the complex 'medieval' discussion of such issues (I am happy to leave that to those who seem to know more about it than John); as I suggested in my last e-mail my overall aim is to attack the bowdlerised 'theory' (which, as I am sure even John will agree, was a caricature of 'Medieval Logic') that Hegel inherited and inadvertently passed on to Engels and Lenin, for example. 

Hope that clears things up.

Last edited by Rosa Lichtenstein (10/21/2015 7:44 am)