What is Kripke Semantics? (Modal Logic)

A video explaining Saul Kripke's Modal Logic Semantics, including possible worlds, the accessibility relation, and the valuation operation. It also includes the semantic meaning of each of the axioms of modal logic, how the accessibility relation can be serial, reflexive, transitive, symmetric and Euclidean by using Axioms, K, D, T, 4, and 5.

Sponsors: João Costa Neto, Dakota Jones, Joe Felix, Prince Otchere, Mike Samuel, Daniel Helland, Mohammad Azmi Banibaker, Dennis Sexton, Yu Saburi, Mauricino Andrade, Will Roberts and √2. Thanks for your support!

[pronouncingvariables]

this is a good video but drawing the arrows out of the word "accessible" made the visuals clunky and confusing. i get why you've done it, but it's distracting as hell and there isn't really any need.

[ajayray]

Thank you for these lectures! They are among the clearest of expositions that I have seen anywhere.

Here, I felt I was following along until the discussion of axiom 5. Could we not have this scenario, without violating it?

V(◻p, w1)
V(p, w2)
V(p, w3)
V(◻q, w2)
V(~q, w3)

...and if so, would R(w2, w3) not hold even though it could be the case that R(w1, w2) and R(w1, w3)?

I thought perhaps the answer lay in considering p alone, but if so, would not R(w2, w3) be vacuously true, regardless of whether we accept axiom 5, as then there are no necessary truths in w2?

[marcomaida]

Please do not use words to make drawings, it looks very confusing !
Thanks for the video ! :D

[RozengerWenger]

You thought about doing videos on phenomenology and/or hermeneutics and their respective thinkers in the future?

[tykjpelk]

What does it mean for a possible world to be accessible? Does it imply that we can go there, and if so in what way? Is it enough that we can make thought experiments about this world without breaking our fundamental beliefs?

[sethapex]

Can someone define the differnt types of logic?
I caught modal, epistemic, temporal, and deontic

[Human_Evolution-]

Ironically I just got to this section in the book I'm reading. The Philosophers Toolkit.

Is there a site or video that shows what every type of logic is and used for?

[Alkis]

Dont't you need to define the negation operator for the strong operator, such that we have "not necessary"?

[TheLilKimooo]

Does that mean our mathematical laws can be false in inaccessible possible worlds?

[jhonjacson]

so... if in w1 p is necessary and you then access w2 is it possible that in the transition, p remains true but loses it's trait of being necessary? Can necessity as a property be lost through transitioning to another world?


And if it can do so, is it possible that this could be the case with things like logical truths, speaking on behalf of a skeptic here.

[messibarca]

Honestly whenever I search for a subject in YouTube your videos pop up, but they’ve never helped me in anything.. it’s just you speaking too fast and making things harder instead of simplifying it for students

[quantumoverlord]

Doing this for my Artificial Intelligence module haha

[JunoMichiaki]

the "artistic design" is annoying as hell but aside from that nice video