all the logic that is talked about in academia has names so people can talk about them. How else would you be able to speak of it? I did not say I KNEW all logic systems in the universe and the names of them all, which is pretty sneaky to ask indirectly. Why not just say is directly if that is what you meant?
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Does logic equal truth?
- Thread starter God lover
- Start date
all the logic that is talked about in academia has names so people can talk about them. How else would you be able to speak of it? I did not say I KNEW all logic systems in the universe and the names of them all, which is pretty sneaky to ask indirectly. Why not just say is directly if that is what you meant?
All,
Perhaps I came across too strong. I am not trying to be a jerk (or worse) who thinks he knows everything. I just realized some of you might be thinking that. I am willing to share and compare knowledge about logic which is what this should be about and not who can do what better than the other person. I apologize if I offended anyone. Let this be about expanding knowledge about deductive logic and not egos. Perhaps I can learn something new as well from this. I am willing to share my knowledge of over 20 years.
I would say I was not taught logic was about validity. Most of the older school philosophers were not either. Those that did say logic is about validity did not SPECIALIZE in logic but mixed in other things. One cannot serve two masters and that is why they spoke the way they did.
Perhaps I came across too strong. I am not trying to be a jerk (or worse) who thinks he knows everything. I just realized some of you might be thinking that. I am willing to share and compare knowledge about logic which is what this should be about and not who can do what better than the other person. I apologize if I offended anyone. Let this be about expanding knowledge about deductive logic and not egos. Perhaps I can learn something new as well from this. I am willing to share my knowledge of over 20 years.
I would say I was not taught logic was about validity. Most of the older school philosophers were not either. Those that did say logic is about validity did not SPECIALIZE in logic but mixed in other things. One cannot serve two masters and that is why they spoke the way they did.
And is all the logic that is talked about in academia logically all the logic there is?
(Yes. You have to say it. You have to stick your own foot in your own mouth, or how will you learn?)
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In the academic sense , YES! The other types you might be thinking are slang uses of the term used entirely in different contexts from the academic. Some people use the term logic when they really mean to USE practical, or common sense, or something makes sense to them, etc. Those are more in the realm of Psychology and not Philosophy.
Historically the two subjects have a rivalry.
Thing is, I'm not thinking of any other types, as typifying would be naming.
So you are against naming? Why?
I have nothing against naming. I'm just asking a question.
Logic is an academic discipline and all academic disciplines have names. That is standard.
I also want to make it clear that Logic is not the same as Mathematical Logic which is so popular that people miss the point of Aristotle.
I think even Aristotle practiced a bit of skepticism once in a while.
In the real world you may see this but that is done by people with bad intentions.
Academically and being honest one simply names things to discuss things without other people being confused to what you are talking about. It has nothing to do with control. You are mixing reality into the intellectual realm.
raw_thought
Well-Known Member
" You are confused: the A is a variable that can stand for any proposition."
Logikal
????
YES!!!! IT is a variable and YES it can stand for any proposition! That proves that logic is about validity and not truth.
It is silly to ask if "A therefore B " is true or false because it A ( and B) can stand for any proposition.
However, the form of Modus tollens is logical, it is valid.
Logikal
????
YES!!!! IT is a variable and YES it can stand for any proposition! That proves that logic is about validity and not truth.
It is silly to ask if "A therefore B " is true or false because it A ( and B) can stand for any proposition.
However, the form of Modus tollens is logical, it is valid.
raw_thought
Well-Known Member
“As Jonathan Lear has put it, “Aristotle shares with modern logicians a fundamental interest in metatheory”: his primary goal is not to offer a practical guide to argumentation but to study the properties of inferential systems themselves.’
Aristotle explicitly says that what results of necessity must be different from what is supposed.
Aristotle adopts a somewhat artificial way of expressing predications: instead of saying “X is predicated of Y” he says “X belongs (huparchei) to Y”.
All the above from
http://plato.stanford.edu/entries/aristotle-logic/
As we can see Aristotle obviously implied that logic is about validity not truth.
Here is a great worksheet that I use in class,
http://people.umass.edu/klement/100/logic-worksheet.html
The below is from that site,
1. All dogs are cats
2. All cats are lizards
3. Therefore, all dogs are lizards
Clearly, this argument is not factually correct, for the premises are false. However, the argument is valid. In other words its logical form is valid. Note that the foundation of logic ( and therefore logic itself) is about form ( validity) not truth. Modus Tollens for example, is expressed by,
A therefore B
Not B
Therefore not A.
It is silly to ask is “ A therefore B” true or false.
https://en.wikipedia.org/wiki/List_of_valid_argument_forms
Aristotle explicitly says that what results of necessity must be different from what is supposed.
Aristotle adopts a somewhat artificial way of expressing predications: instead of saying “X is predicated of Y” he says “X belongs (huparchei) to Y”.
All the above from
http://plato.stanford.edu/entries/aristotle-logic/
As we can see Aristotle obviously implied that logic is about validity not truth.
Here is a great worksheet that I use in class,
http://people.umass.edu/klement/100/logic-worksheet.html
The below is from that site,
1. All dogs are cats
2. All cats are lizards
3. Therefore, all dogs are lizards
Clearly, this argument is not factually correct, for the premises are false. However, the argument is valid. In other words its logical form is valid. Note that the foundation of logic ( and therefore logic itself) is about form ( validity) not truth. Modus Tollens for example, is expressed by,
A therefore B
Not B
Therefore not A.
It is silly to ask is “ A therefore B” true or false.
https://en.wikipedia.org/wiki/List_of_valid_argument_forms
Logic as Aristotle put forth is NOT only about validity.
Dude you are confused still: do you know what the difference is between a PREMISE and an ARGUMENT?
Secondly there is NO if A therefore B. IF A, then B is a PREMISE in Modus Ponens and Modus Tollens. The way you present the argument you are leaving out a premise. Modus ponens and Modus Tollens deal with AT LEAST two premises and are logically SOUND. Sound again means TRUE; and VALID refers to a method of truth preservation: that is, there are no cases where the conclusion can be false if the premises are true.
Dude you are confused still: do you know what the difference is between a PREMISE and an ARGUMENT?
Secondly there is NO if A therefore B. IF A, then B is a PREMISE in Modus Ponens and Modus Tollens. The way you present the argument you are leaving out a premise. Modus ponens and Modus Tollens deal with AT LEAST two premises and are logically SOUND. Sound again means TRUE; and VALID refers to a method of truth preservation: that is, there are no cases where the conclusion can be false if the premises are true.
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Again and again you are hooked up on what a math teacher says and NOT Aristotle. Give me an example of Aristotle using DEDUCTION that is not a FALLACY and uses FALSE Premises!!! I bet the only time Aristotle uses false premises are times he demonstrates there is an error in the reasoning.
I never stated that people could not misuse logic. People misuse the word logic daily. You seem to be hung up on popular beliefs. Riddle me this: if logic is about VALIDITY only why does Aristotle and every logic book discuss INFORMAL FALLACIES? NOTE the term "INFORMAL" which means CONTENT matters. Can a valid argument commit an informal fallacy? Riddle me that Riddler. If it is POSSIBLE for a valid argument with true premises to commit an informal fallacy this DISPROVES Logic is about Validity only.
Aristotle himself divided LOGIC into two categories: Major logic and Minor Logic. And NO the context does not state this is division is about DEDUCTIVE and INDUCTIVE logic types. Read about it and get back to me. All forms of logic are objectively FORMAL. The reason it is formal is the pattern of the reasoning. The pattern is how we distinguish inductive from deductive hence it all has a FORM. If you can recognize it IT HAS FORM. Today we would use the modern term PATERN. If there is a VISUAL DIFFERENCE there is a PATTERN (AKA form). Inductive reasoning has a visual pattern. Therefore, inductive reasoning is FORMAL. Did you see that Modus Ponens I snuck in there?
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raw_thought
Well-Known Member
Umm yeah I do know the difference between a premis and an argument. EVERY premise (and even the conclusion ) can be false and the argument is still valid. Truth has nothing to do with logic
Anyway, disagree with EVERY logic professor in the world,its your right. But dont expect to be taken seriously .
One can have a perfectly logical argument that has no truth to it.
For example,
1. All Martians eat snakes.
2. Bob is a Martian
3. Therefore Bob eats snakes.
Read that site I gave from the University of Massachusetts !!!!
Anyway, disagree with EVERY logic professor in the world,its your right. But dont expect to be taken seriously .
One can have a perfectly logical argument that has no truth to it.
For example,
1. All Martians eat snakes.
2. Bob is a Martian
3. Therefore Bob eats snakes.
Read that site I gave from the University of Massachusetts !!!!
There is no question that once upon a time logic was NOT all about validity.
Proof: There is still today evidence of logic being a form of having knowledge gaining knowledge; today this is a field called Epistemology. Look up "Material Logic" on Google. The term Material Logic has now been substituted by the field of Epistemology. Thus, you will not find so much stuff on it by that name. however there is historical evidence it exist as the google results will show. This term is predominantly still USED in Catholic teachings on logic. I am sure you will find authors in Notre Dame University and other Catholic univerisities that begin with "father" and other titles.
Proof: There is still today evidence of logic being a form of having knowledge gaining knowledge; today this is a field called Epistemology. Look up "Material Logic" on Google. The term Material Logic has now been substituted by the field of Epistemology. Thus, you will not find so much stuff on it by that name. however there is historical evidence it exist as the google results will show. This term is predominantly still USED in Catholic teachings on logic. I am sure you will find authors in Notre Dame University and other Catholic univerisities that begin with "father" and other titles.
Let me STOP you! Show me where I said logic has nothing to do with validity. I know some parts are about validity. Why have you not answered or addressed any of the issues I brought up. I know you can have validity with false premises. I never stated otherwise. Show me where I said you can't have a valid argument with false premises????
Address my points and please stop using your own agenda trying to make me sound crazy in public when it is you. you are not presenting anything I said, but what is in your head. Answer my question in my last post about informal fallacies please. If logic is only about validity why are informal fallacies taught?
raw_thought
Well-Known Member
I particularly like the question labeled "J"! *
Try to decide if it is valid before looking at the answer!
At the U of Massachusetts site!
Try to decide if it is valid before looking at the answer!
At the U of Massachusetts site!
Curious George
Veteran Member
Sound and valid are different.
Valid is just without fallacy. Sound is valid and true premises.