Logic 101 (#29): Disjunctive Syllogism

Disjunctive syllogism says that if you have P v Q and ~P, you can conclude Q.

[albinsopaj]

I started to like the video in the first 10 seconds. Great people explain topics in simple but fun way.

[ActNormalThinkFresh]

for your example. shouldn't it be "the food does not have chicken, therefore it is beef" because p= chicken, q=beef, not chicken therefore beef in order to support ~p, therefore q?

[marlondoria]

amazing! What was i doing when i was taking this course!

[angsans]

FYI: Your example syllogism (the chicken and the beef) does not match the P & Q formula next to it.

[ashleynewton]

This was great. Super helpful. Thank you!

[willhollingsworth]

Can a correctly formulated argument have contradictory premises in syllogistic logic???

[Cholo]

"Something happens, " temporally, between 1. and 2. so that 1. is negated, right?  My question:  What happens between 1. and 2.?  (I'm not trying to be argumentative.)

[muhammadaiman]

How about i change it into p or q, and not q, then p. Is it same? Hope anyone can reply this thanks in advance!!!

[andrzejgieralt]

Hello, great video! Is there a way to prove disjunctive syllogism formally, using the '11 axioms'?

[graysonfisher]

thanks for explaining this so well, really cleared things up :)

[thelastcipher]

why is the third row ~p --> q? i thought material implication was supposed to be ~p OR q?

[PunmasterSTP]

Syllogism? More like silly-gism, because William dumping all this knowledge on us for free on YouTube is crazy!

[LordOfThunderUK]

I don't see the logic on these three points as a whole.

If 2 is right then it is not part of 1, ie The food has Beef

Taking into account the 2 would be true then 1 has to be rectified and say:

1 The food has Chicken
2. The food does not have Beef
3. Therefore, it has Chicken

I listen to the rest of the video and I was getting a headache, what a way to complicate an argument.

I will give you an example of how silly the argument is:

Say in a restaurant a waiter shows a menu with a choice of two items on the chosen food then after the order has been placed, the waiter comes and says that one of the items is not there:

The client would argue why it says in the menu something that they don't have (Your point 2)

The logical approach is to rectify point 1. (remove what it does not have) so point 1 reflects a true statement.

[edberaga]

question... can I do the distuntive syllogism with modus tollens too?
like:
~P v q
~p
therefore ~q

[kimandreasheroy]

1:11 Damn, these videos are so good, but it annoyed the heck out of me that he wrote both the sentences on line 2 and the conclusion wrong 😅