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Does logic equal truth?

Willamena

Willamena

Just me
Premium Member
Logikal said:
This shows me all of you have studied MATH. You just don't know the difference. You should be able to tell a tree by its fruit. Do any of you even know there is a branch literally called MATHEMATICAL LOGIC? This is what you refer to. You ought to be using the FULL NAME of the logic you refer to as LOGIC. For thousands of years prior to Mathematical logic people KNEW logic as deductive logic. Inductive logic is another name for science. Now mathematical logic is popular people don't care about distinctions anymore.
Click to expand...
What if our logic doesn't currently have a name?
 
L

Logikal

Member
raw_thought said:
1. All Martians eat snakes
2. Bob is a Martian
3. Therefore Bob eats snakes.
That is a VALID argument that is not true.
PLEASE take a basic logic course!!!!
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I never said valid means true. Why are you attributing that to me? I know the difference. Truth in logic is referred to as SOUNDNESS. My claim is that Aristotle did not say logic is about validity, but you and others do. This thought was not brought up until the invention of Mathematical Logic.
 
R

raw_thought

Well-Known Member
ummm no
Modus tollens is obviously about logic and validity and not truth. The fact that Modus Tollens is about variables and not verifiable propositions shows that it is about validity not truth .
 
R

raw_thought

Well-Known Member
Modus Tollens says,
A therefore B
not B
therefore not A.
is "A therefore B" true or false?????
Of course such a question is silly because modus tollens is about validity not truth!
 
L

Logikal

Member
Willamena said:
What if our logic doesn't currently have a name?
Click to expand...

Academically logic is categorized by specific names. Many deductive systems are not pure deduction such as modal logic, intutitional logic, etc. Mathematical logic at some point requires knowledge of MATH concepts.
Logic taught in Philosophy does not require MATH. Today Mathematical logic is taught as "logic" and youngsters don't know the difference. Philosophers had no need for math to analyze arguments.
 
Willamena

Willamena

Just me
Premium Member
Logikal said:
Academically logic is categorized by specific names. Many deductive systems are not pure deduction such as modal logic, intutitional logic, etc. Mathematical logic at some point requires knowledge of MATH concepts.
Logic taught in Philosophy does not require MATH. Today Mathematical logic is taught as "logic" and youngsters don't know the difference. Philosophers had no need for math to analyze arguments.
Click to expand...
You didn't answer my question, but okay.
 
L

Logikal

Member
raw_thought said:
Modus Tollens says,
A therefore B
not B
therefore not A.
is "A therefore B" true or false?????
Of course such a question is silly because modus tollens is about validity not truth!
Click to expand...

You are talking about a FORM and not an argument!!!
I can use modus tollens with legit propositions and the argument will be SOUND. Note all sound arguments MUST be Valid.
If Rex is a dog, then Rex is an animal.
Rex is a dog.
Therefore, Rex is an animal.

Who cares about validity when SOUNDNESS is the greater concept which Aristotle would agree with. It is those OTHER FOLK that think logic is only about form.
 
L

Logikal

Member
raw_thought said:
Even you said that logic is only about the RELATIONSHIP between Propositions .
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I find most people outside of PhD's in Philosophy are taught the wrong definition of the term PROPOSITION.
Math teaches that propositions are declarative sentences, which is not accurate. This is new school teachings. Old school never taught that definition. How do you define "proposition"? Wiki will not help you. Even Wiki get a lot of things wrong technically.
 
R

raw_thought

Well-Known Member
Aristotle gave us the rules of logic
laws of contradiction etc
those laws are about logical form (A or not A etc) His rules of logic are based on variables and so cannot be about truth.
Is "A therefore B" true or false??
Obviously a silly question because logic is not about truth it is about validity!
 
L

Logikal

Member
raw_thought said:
Aristotle gave us the rules of logic
laws of contradiction etc
those laws are about logical form (A or not A etc) His rules of logic are based on variables and so cannot be about truth.
Is "A therefore B" true or false??
Obviously a silly question because logic is not about truth it is about validity!
Click to expand...

You are confused: the A is a variable that can stand for any proposition. You methodology is a bit off from old school teachings in Philosophy.

The question is not stated correctly.
 
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