Logic 101 (#28): Modus Tollens
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- Опубліковано 14 жов 2024
- gametheory101.c...
Modus tollens says that if P implies Q is true and not Q is true as well, then ~P must follow as a result.
For example, suppose
"If I am Miley Cyrus, I am crazy."
and
"I am not crazy."
Then there is no way in hell I am Miley Cyrus.
Definitely appreciated the proof by modus ponens. That helped make the modus tollens a lot clearer as to why it works.
Thank you so much. Translating the word meanings really really helps me to understand the different forms.
Thank you for your effort in clarifying this concept
Thank you, best example of modus tollens on youtube
that truth table made my life complete
I love how you can tell this came out 10 years ago by the Miley Cyrus being “crazy” reference 😂
How do you know when to use certain logical equivalencies when constructing new ways of saying the same thing or for simplifying the logic, such as you did by converting Modus Tollens to Modus Pollens and using contraposition? Is it just a matter of memorizing all the formulas, rules of inferences, laws, equivalencies, etc. so that it will pop into your head automatically? I'm having to do a lot of research to be able to simplify or convert just one implication. Hope this question makes sense
Personally I think one of the best strategies (as far as homework and tests go) is to look at a previous question or part of the question and see if it is setting you up for anything. Since William talked about modus ponens in the previous video, I think that is a reasonable place to start. I also think that there can be *many* ways to prove something, and if a way seems simple or if it is the only solution you can think of (like on a test), I'd say go for it!
i got confused at the truth table
What made you confused? If you let me know, I can try to explain.
Could it be that you have the T/F's wrong. Shouldn't it be FALSE implies TRUE = TRUE?
Q: What does a logical eagle use to catch its prey?
A: Modus talens.
😎
If it rains then I get wet
Acc to M.T. if I don't get wet then it is not raining
How so? It could be he case that its raining but I am under an umbrella.(which is why I don't get wet)
Sudev Sen If you want to find out if the reverse is true, you can't use the same 2 premises. You have to use the conclusion and one of the premises. That is a different instance of inference and it's separate from the first one. You have to construct different proof table for that where you take the conclusion and one of the premises as the two premises of this inference.
Edgars The ipmication a > b doesn't mean that b > a .
+Sudev Sen Let me try to answer it. Your example is a case of untrue premise. "If it rains, then I get wet". This is not true as you could easily be inside a house or under an umbrella so your premise isn't a TRUTH statement.
So that's why your conclusion isn't sound (but the argument is valid).
@@edgars2113 Yeh, so it must be understood that you get wet IN GENERAL, in all cases. If you get wet in all cases if it rains then the argument is valid
can you make a video about how to complete the truth table?
ua-cam.com/video/UaGM8T4o9xI/v-deo.html
ua-cam.com/video/Zbr0c5QCpos/v-deo.html
why is this different from reductio ad absurdum
Reductio ad absurdum tries to prove an argument by showing that if it were not true, it would lead to something absurd. One of the examples on Wikipedia ( en.wikipedia.org/wiki/Reductio_ad_absurdum ) is that if the world were flat, we'd expect people to fall off the edges, which most people consider to be absurd.
Modus tollens just deals with the negation of a consequent showing the negation of the premise. I'm sure I'm not quite explaining it correctly, but maybe William could jump in and school us.
I think this guy hates Miley Cyrus, However he is perfect 🤣
Cool thanks for video
nice video
thanks a lot!
Thanks
Solving logic puzzles with modus ponens and modus tollens: ua-cam.com/video/DKioUaN3be4/v-deo.html