Graham Priest - 1. What is logic?

LOGIC: A SHORT INTRODUCTION - Lecture 1
Graham Priest, CUNY Graduate Center (NY), University of Melbourne

[@metalmunkey42]

Blast from the past! It's 30 years (1987) since I experienced Professor Graham Priest's excellent Philosophy of Religion lectures in Philosophy 100 at the University of Western Australia :)

[@DarrenMcStravick]

UWA??? Get out! Hopefully he still visits the campus at the very least!

[@pitkataival]

Great introduction! I have a question @5.35 concerning the introduced example "dark clouds => it will rain", which is said @6.45 to exemplify **inductive reasoning** ... would it not rather be an example of **deductive reasoning** with the implicit assumption, that the gathering of dark clouds implies probable rain? (1) Deduction : specific observation ("cause" A) & general expectation ("causality" A=>B) => specific expectation ("effect" B) EX: "(A) clouds have gathered & (A=>B) when clouds gather, it is likely to rain => (B) it is likely to rain" (2) Induction: specific observation ("cause" A) & specific observation ("effect" B) => general expectation ("causality" A=>B) EX: "(A) clouds have gathered & (B) it came to rain => (A=>B) when clouds gather, it is likely to rain" (3) Abduction: general expectation ("causality" A=>B) & specific observation ("effect" B) => specific expectation ("cause" A) EX: "(A=>B) when clouds gather, rain is likely to follow & (B) it rained => (A) clouds must have gathered In fact, here in each mode of inference, we have two premises combining with one conclusion, but the example just gives one premise. So there is no explicit bridge from the premise to the conclusion. Since on the level of logical inference, we have no access to the semantics and meaning of the propositions, but only to their logical structure, we need a bridging assumption, that i here guess is implicit; but doing so, it is the deductive pattern shown in (1) that seems to fit the example, not the inductive pattern (2), nor the abductive pattern (3) The fact that rain does not necessarily always follow from a gathering of dark clouds, seems to be a modal aspect of the assumed expectation (A=>B) itself, ie part of the assertion made, rather than belonging to the mode of inference. Hence the "different character" attributed to the whole argument mentioned @6:00 does not contradict the logical necessity of the inference conveyed by deduction, as opposed to the asserted expectation failing to necessarily hold true, since it is a modal, rather than a categorical assertion. Or am i am mixing things up? I am cheating by explicitly introducing the modal aspect and the implicit expectations, thus missing the point of the example? Anybody has a clue? kind regards

[@lindsayromo706]

Hi, will there be an upload of sessions 2-6? I’m currently taking a propositional logic class and have finally come across paraconsistent logic and I’ve been struggling with Lemmons logic system and your lecture here has helped immensely. Thanks!

[@DarrenMcStravick]

What would be to sound premises what logic is to valid conclusions? (Looking for some general formal discipline, not some specific science.)

[@Auricfield]

Hi Graham - could you please suggest a way to begin learning what you are teaching. Not at a university level, just something I could do on my own at home that will teach and test me. Thanks

[@lupo-femme]

He also has a small book from the 'Very short Introductions' series by Oxford University Press, it's called 'Logic: A Very Short Introduction', there you have a good beginners material.

[@yeager6882]

Susan Langer's An Introduction to Symbolic Logic

[@Shankar-Bhaskar]

@@yeager6882 It's a pretty advanced and difficult book, I would recommend 'Logic' by Siu-Fan Lee.

[@yeager6882]

@@Shankar-Bhaskar To each his own learning style. I look at Lee's book and I see a run of the mill, typical, introduction to logic. They are nearly all the same. I am not saying there is a problem with that, just that there are already scores and scores of these books. The only distinction to those books lies in the idiosyncratic ones written by some of the heavy hitters. I cannot recommend those either because they get into their own personal interpretations and nuances that beginner student either are not going to pick up on or understand, but may also lead to confusions. There is enough solid ground in logic to justify avoiding those matters in an introductory texts. Another issue is that people learn in at least two separate ways; this bears itself out in difficult and technical subjects like math and logic. The standard texts are for those who take simplicity for granted; for those who care little for "understanding." They are really good at following rules, but care little about justifications, meanings, explication, and the "whys." They are part of the "just tell me" culture. The people would care about these latter matters will not find the standard texts approachable and/or interesting. They will "seem" difficult because they do not make sense to this type of person; and they would be correct. This type of person needs to know "why?" and often enough the text/teacher can't tell them why. The subject becomes nothing more than drudgery. In an effort to accommodate both types, I found that Kahane, Hausman, et al Logic and Philosophy: A Modern Introduction (11th Edition) a fair compromise. I have a couple of new texts, but I haven't looked at them yet. The field of Logic is as much guilty as any field that slowly extracts valuable and necessary elements of the subject over time in the name of development or advancement. People loose their understandings and foundations, and it becomes fatal as one proceeds. This is why upper level math and graduate level math has foundational requirements like real analysis, set theory, etc. These could have and should have been taught in elementary school as an alternative stream of mathematical education for "other" types of learners. Of course math and other such subjects are always being taught by the same type of people who alienate other types. The individual goes on thinking they are bad at math. No one is bad at math, they just weren't taught in a way conducive and necessary to their learning style. Regarding mathematical logic we can see this very clearly in model theory and proof theory. They are equivalent, but model theory is more basic and explicative. Proof theory is more efficient. Most of our math and logic classes/texts are taught like proof theory. Many of us find this unacceptable for learning. We want model theory. And just as an aside, the real brains behind logic and its development were, by disposition (if not explicitly), model theorists, not proof theorist. Logic is the same. I find your comment that Langer's text is too advanced, puts you in this category of learning type tyranny. There is nothing advanced about it for the student who learn through the explicative style. Langer walks the student through every set of building logic and its system through 1st order logic. To the other type, they don't care, and they confuse this with being "too advanced." Image if the tables were turned in our mainstream education of mathematics textbooks and classes! Once one learns in this way, all that front material in standard logic text is already entailed. There really isn't much to teach. They know because they were taught properly. And this is why we end up with these countless route and drill texts. Langer's text was one of the very first textbooks for logic written (that would fulfill 1st order), and so it had to be written in a nurturing way. It succeeds in this matter. Another earlier, but more focused on finer details of concepts, would be S. Stebbing's A Modern Introduction to Logic. One can take either path to learning any subject, but if you take the former path (the route and drill, copy/paste, etc), you will never progress beyond a certain point unless you go back and study the history and the subject's development.

[@Shankar-Bhaskar]

@@yeager6882 I have downloaded a copy of Langer's book, I'll have to go through it before I begin to recommend it. There are still a lot of mental cobwebs and doubts that need to be cleared in my head about the subject of logic.

[@anon8109]

@2:20 the example is missing a few premises for the argument to be a good one. The cities of a country are in the country. The capitol of a country is a city. If a plane lands in a city then it lands in any country that city belongs to. Italy is a country.

[@jayaramj9630]

It is inherent By definition.

[@raphaelmourao7]

Portuguese subtitles please !!!