Gary f: "pet theories"? :)
Best, J On Tue, Oct 24, 2017 at 3:00 PM, <[email protected]> wrote: > Jerry R, list, > > > > Lowell 2.4 introduces the “conditional *de inesse,*” as Peirce calls it, > as the most simple and basic logical form that needs to be represented in > the system of existential graphs. It was not obvious to me at first *why* > Peirce chose this particular form as the place to start; so in the > presentation of Lowell 2 on my website, I inserted as a sidenote a section > from one of his 1898 Cambridge Lectures that explains in more detail what > the logical issue is and why the “conditional *de inesse*” is so > important for the Peircean approach to formal logic in the Lowells. > > > > And of course, you have to understand the part formal logic and > existential graphs play in Peirce’s whole philosophy in order to see the > point of what he’s doing in Lowell 2. So if you weren’t following Lowell 1 > very closely, you probably won’t follow Lowell 2 very closely either. That > may mean you have to set aside your own pet theories and predilections to > get on board with Peirce’s train of thought. > > > > Here’s the 1898 excerpt that explains the importance of the “conditional *de > inesse*” *(R441, RLT 125-6, NEM4 169-70):* > > > > Cicero informs us that in his time there was a famous controversy between > two logicians, Philo and Diodorus, as to the signification of conditional > propositions. Philo held that the proposition “if it is lightening it will > thunder” was true if it is not lightening or if it will thunder and was > only false if it is lightening but will not thunder. Diodorus objected to > this. Either the ancient reporters or he himself failed to make out > precisely what was in his mind, and though there have been many virtual > Diodorans since, none of them have been able to state their position > clearly without making it too foolish. Most of the strong logicians have > been Philonians, and most of the weak ones have been Diodorans. For my > part, I am a Philonian; but I do not think that justice has ever been done > to the Diodoran side of the question. The Diodoran vaguely feels that there > is something wrong about the statement that the proposition “If it is > lightening it will thunder” can be made true merely by its not lightening. > > Duns Scotus, who was a Philonian , as a matter of course, threw > considerable light upon the matter by distinguishing between an ordinary > *consequentia*, or conditional proposition, and a *consequentia simplex > de inesse*. A *consequentia simplex de inesse* relates to no range of > possibilities at all, but merely to what happens, or is true, *hic et > nunc*. But the ordinary conditional proposition asserts not merely that > here and now either the antecedent is false or the consequent is true, but > that in each possible state of things throughout a certain well-understood > range of possibility either the antecedent is false or the consequent true. > So understood the proposition “If it lightens it will thunder” means that > on each occasion which could arise consistently with the regular course of > nature, either it would not lighten or thunder would shortly follow. > > Now this much may be conceded to the Diodoran, in order that we may fit > him out with a better defence than he has ever been able to construct for > himself, namely, that in our ordinary use of language we always understand > the range of possibility in such a sense that in some possible case the > antecedent shall be true. Consider, for example, the following conditional > proposition: If I were to take up that lampstand by its shaft and go > brandishing the lamp about in the faces of my auditors it would not > occasion the slightest surprise to anybody. Everybody will say that is > false; and were I to reply that it was true because under no possible > circumstances should I behave in that outrageous manner, you would feel > that I was violating the usages of speech. > > I would respectfully and kindly suggest to the Diodoran that this way of > defending his position is better than his ordinary stammerings. Still, > should he accept my suggestion I shall with pain be obliged to add that the > argument is the merest *ignoratio elenchi* which ought not to deceive a > tyro in logic. For it is quite beside the question what ordinary language > means. The very idea of formal logic is, that certain *canonical forms* > of expression shall be provided, the meanings of which forms are governed > by inflexible rules; and if the forms of speech are borrowed to be used as > *canonical > forms of logic* it is merely for the mnemonic aid they afford, and they > are always to be understood in logic in strict technical senses. These > forms of expression are to be defined, just as zoologists and botanists > define the terms which they invent, that is to say, without the slightest > regard for usage but so as to correspond to natural classifications. That > is why I entitled one of the first papers I published, “On the Natural > Classification of Arguments.” And by a *natural* classification, we mean > the most pregnant classification, pregnant that is to say with implications > concerning what is important from a strictly logical point of view. > > Now I have worked out in MS. the whole of syllogistic in a perfectly > thoroughgoing manner both from the Philonian and from the Diodoran point of > view. But although my exposition is far more favorable to the Diodoran > system even than that of DeMorgan in his *Syllabus of Logic*, which is > much the best presentation of the Diodoran case ever made by an adherent of > it, yet I find that the Philonian system is far the simpler,— almost > incomparably so. You would not wish me to take you through all those > details. This general statement is all that is appropriate for this brief > course of lectures. > > Be it understood, then, that in logic we are to understand the form “If A, > then B” to mean “Either A is impossible or in every possible case in which > it is true, B is true likewise,” or in other words it means “In each > possible case, either A is false or B is true.” > > > > *From:* Jerry Rhee [mailto:[email protected]] > *Sent:* 23-Oct-17 18:51 > > Gary f, list: > > Thank you for that posting. > > I must assert though, > > I am surprised that if A is true, B is true, for I thought: if A were > true, C would be a matter of course. > > Does B and not C surprise you? > > http://www.iupui.edu/~arisbe/menu/library/bycsp/L75/ver1/l75v1-04.htm > > Best, > Jerry Rhee > > > > On Mon, Oct 23, 2017 at 9:36 AM, <[email protected]> wrote: > > Continuing from Lowell 2.3, > > https://www.fromthepage.com/jeffdown1/c-s-peirce- > manuscripts/ms-455-456-1903-lowell-lecture-ii/display/13602: > > The most immediately useful information is that which is conveyed in > conditional propositions, “*If* you find that this is true, *then* you > may know that that is true.” Now in ordinary language the conditional form > is employed to express a variety of relations between one possibility and > another. Very frequently when we say “If A is true, then B is true,” we > have in mind a whole range of possibilities, and we assert that among all > possible cases, every one of those in which A is true will turn out to be a > case in which B is true also. But in order to obtain a way of expressing > that sort of conditional proposition, we must begin by getting a way of > expressing a simpler kind, which does not often occur in ordinary speech > but which has great importance in logic. The sort of conditional > proposition I mean is one in which no range of possibilities is > contemplated, which speaks only of the actual state of things. “If A is > true then B is true,” in this sense is called a conditional proposition *de > inesse*. In case A is not true, it makes no assertion at all and > therefore involves no falsity. And since every proposition is either true > or false, if the antecedent, A, is not true, the conditional *de inesse* > is true, no matter how it may be with B. In case the consequent, B, is > true, all that the conditional *de inesse* asserts is true, and therefore > it is true, no matter how it may be with A. If however the antecedent, A, > is true, while the consequent, B, is false, then, and then only is the > conditional proposition *de inesse* false. This sort of conditional says > nothing at all about any real connection between antecedent and consequent; > but limits itself to saying “If you should find that A is true, then you > may know that B is true,” never mind the why or wherefore. > > *http://gnusystems.ca/Lowell2.htm <http://gnusystems.ca/Lowell2.htm>* }{ > Peirce’s Lowell Lectures of 1903 > > https://fromthepage.com/jeffdown1/c-s-peirce-manuscripts/ms-455-456-1903- > lowell-lecture-ii > > > > > ----------------------------- > PEIRCE-L subscribers: Click on "Reply List" or "Reply All" to REPLY ON > PEIRCE-L to this message. PEIRCE-L posts should go to > [email protected] . 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