Speakpigeon
Valued Senior Member
Good, we agree on that.
Are you at all aware that mathematical logic sees all arguments with contradictory premises as valid, whatever the conclusion?
EB
The Monkey argument: Valid? not valid?
- Thread starter Speakpigeon
- Start date
Are you at all aware that mathematical logic sees all arguments with contradictory premises as valid, whatever the conclusion?
EB
DaveC426913
Valued Senior Member
Agree.
Speakpigeon
Valued Senior Member
Sorry to disappoint, but nothing of the sort. I'm only busy surveying how people think about logical arguments.
EB
Speakpigeon
Valued Senior Member
That's absolutely not true and a misrepresentation of the facts. I took the time to reply to many people, even when they had nothing relevant or even sensible to say. Most comments are straightforward derails. I ask a question, if you don't feel like replying, then fuck off.
EB
Speakpigeon
Valued Senior Member
No information is missing. The argument should be considered as is.
If we allowed for possibly missing information, we could continually add some new missing information and never get any answer as to validity.
EB
Does it account for people that do not care for your posts?
Truly though, your (dumbass) posts do add a distinct flavor that one can grow to appreciate.
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What is the point if it distracts from the truth? Joe might not be a monkey. But if we stay locked into the paradigm you’ve provided, then Joe is a monkey, only by default.
DaveC426913
Valued Senior Member
No, Joe could be a monkey - or a squid. (For visual types, I Venn diagrammed it in post #15.)
As Sarkus says: all the premises can be true, yet the conclusion can be false.
That's what SP is trying to get at. Is the argument valid?
Not imo according to this eye-opener:
No - never studied the subject. But it implies you should not have agreed with me! In fact it implies only the first poll option is ever valid!
Is this my 'a ha' moment? When I come to appreciate that mathematical logic can be profoundly illogical?! Some subjects best never delved into. Sanity and all that.
Okay, gotcha. To that end, I'd say no...it's not valid.
This thread, similar to the many others that Speakpigeon has posted on essentially the same topic, is currently in Human Science. I am wondering where the science is.
I'm also wondering why Speakpigeon has such a one-track mind, but that's another topic.
I'm also wondering why Speakpigeon has such a one-track mind, but that's another topic.
I'm not aware of that. I'd like to see an argument in mathematical logic (whatever that is) with contradictory premises (whatever mathematical premises are).
Yazata
Valued Senior Member
Speakpigeon
Valued Senior Member
I completely agree with your view expressed here that an argument with contradictory premises is both meaningless and not valid.
And, I repeat, in mathematical logic, ALL arguments with contradictory premises are IPSO FACTO valid.
EB
Speakpigeon
Valued Senior Member
Yes, exactly. I agree with that.
And, I repeat again, in mathematical logic, ALL arguments with contradictory premises are IPSO FACTO valid.
And if it's an eye-opener for you, welcome to our world.
EB
Uh huh. Wow. At this point progress might be easier if you can furnish an example or two of an invalid argument(s), assuming such beasts exist in mathematical logic!
Invalid argument:
P1. All As are B.
P2. C is an A.
Conclusion. C is not B.
On the other hand, this is a valid argument:
P1. All As are B.
P2. No As are B.
C. Elvis is alive.
Just to expand a little, here's one way contradictory premises can be used to prove anything at all:
1. P is true
2. P is false.
3. Either P is true or Q (true because of step 1)
4. But P is not true (because of step 2).
5. Therefore, since P is not true, Q must be true (using 3 and 4).
A specific example:
1. The sky is blue.
2. The sky is not blue.
3. Either the sky is blue or Elvis is alive (true because we know the sky is blue, from 1).
4. But the sky is not blue (as we know from 2).
5. Therefore, Elvis is alive (because we know the sky isn't blue, and this is the only alternative contemplated in 3, which we have already established is a true statement).
1. P is true
2. P is false.
3. Either P is true or Q (true because of step 1)
4. But P is not true (because of step 2).
5. Therefore, since P is not true, Q must be true (using 3 and 4).
A specific example:
1. The sky is blue.
2. The sky is not blue.
3. Either the sky is blue or Elvis is alive (true because we know the sky is blue, from 1).
4. But the sky is not blue (as we know from 2).
5. Therefore, Elvis is alive (because we know the sky isn't blue, and this is the only alternative contemplated in 3, which we have already established is a true statement).
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Speakpigeon
Valued Senior Member
???
It's just so easy given what I said I wonder why you need me. Still, here it is:
P;
Not P;
Therefore, Q.
Not P;
Therefore, Q.
See? Any P and any Q at all.
Of course, you may prefer more concrete, real-world examples, so here is a nice one:
Being a farmer is a nice occupation but it is hard work;
It is true that Donald Trump is a farmer;
It is not true that Donald Trump is a farmer;
Therefore, Donald Trump is the third son of Kim Il Sung, the brother-in-law of Andrei Gromyko, and he was the president of the United States of American in 1961 when a junkie called John Fitzgerald Kennedy shot dead Pope Martin Luther King.
It is true that Donald Trump is a farmer;
It is not true that Donald Trump is a farmer;
Therefore, Donald Trump is the third son of Kim Il Sung, the brother-in-law of Andrei Gromyko, and he was the president of the United States of American in 1961 when a junkie called John Fitzgerald Kennedy shot dead Pope Martin Luther King.
Would that be concrete enough and absurd enough for you?
LOL, you must be falling from the wardrobe, as we say in French.
So, no revelation from me here, I'm afraid. You see, ha-ha, it's all publicly available material and public knowledge, as they say, since about 1853, in theory, with the publication of George Boole's book on logic. Time to wake up?
EB