A logical argument

Philosophical, mathematical and computational logic, linguistics, formal argument, game theory, fallacies, paradoxes, puzzles and other related issues.

A logical argument

Postby the_stoic on July 31st, 2011, 11:42 pm 

I took a college logic & reasoning course a while back, and was taken aback by something new. A logic based not on syllogisms, or in otherwords, A, B, and C. I also learned about fallacies, and that the most logical argument is that which is with the fewest fallacies. I was confused because it seemed that there was no status quo to logic. Is this viewpoint valid, or is any argument which cannot be summed up in numbers not valid.
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Re: A logical argument

Postby chris12 on November 8th, 2011, 9:36 pm 

the_stoic wrote:I took a college logic & reasoning course a while back, and was taken aback by something new. A logic based not on syllogisms, or in otherwords, A, B, and C. I also learned about fallacies, and that the most logical argument is that which is with the fewest fallacies. I was confused because it seemed that there was no status quo to logic. Is this viewpoint valid, or is any argument which cannot be summed up in numbers not valid.


What do you actually mean by "any argument which cannot be summed up in numbers not valid" ??
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Re: A logical argument

Postby Fredd on February 19th, 2012, 7:54 am 

the_stoic wrote:I took a college logic & reasoning course a while back, and was taken aback by something new. A logic based not on syllogisms, or in otherwords, A, B, and C. I also learned about fallacies, and that the most logical argument is that which is with the fewest fallacies. I was confused because it seemed that there was no status quo to logic. Is this viewpoint valid, or is any argument which cannot be summed up in numbers not valid.


My reply just now to ornela in the "Demarcating logic" thread seems to address this question also, assuming "summed up in numbers" refers to logic as a branch of math as opposed to philosophical logic (or dialectical branch thereof).
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Re: A logical argument

Postby flannel jesus on February 23rd, 2012, 4:13 am 

demasontoth wrote:A logical argument means demonstrating truth or false.

You'd be closer if you replaced "truth or false" with "validity or invalidity".

A logically valid argument may have a false conclusion.
A logically invalid argument may have a true conclusion.
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Re: A logical argument

Postby Benzie on February 23rd, 2012, 8:14 am 

Fredd wrote:My reply just now to ornela in the "Demarcating logic" thread seems to address this question also, assuming "summed up in numbers" refers to logic as a branch of math as opposed to philosophical logic (or dialectical branch thereof).


Isn't mathematics surely a branch of logic?

flannel jesus wrote:
demasontoth wrote:A logical argument means demonstrating truth or false.

You'd be closer if you replaced "truth or false" with "validity or invalidity".


And don't forget 'sound' arguments too, when I did logic it was always a pain distinguishing between valid/invalid arguments and sound/unsound arguments and how the two interacted. It's not hard, but as a wide-eyed 1st year student it was tricky to take in...
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Re: A logical argument

Postby Fredd on February 23rd, 2012, 4:18 pm 

Benzie wrote:
Fredd wrote:My reply just now to ornela in the "Demarcating logic" thread seems to address this question also, assuming "summed up in numbers" refers to logic as a branch of math as opposed to philosophical logic (or dialectical branch thereof).


Isn't mathematics surely a branch of logic?


Yes, that's the usual classification.

"Today, logic is both a branch of mathematics and a branch of philosophy." http://plato.stanford.edu/entries/logic-classical/

I liked that explanation for where I thought the exchange was leading, so adopted its terminology.

Philosophically, I think the proper hierarchy is Philosophy -> logic -> math, and that the posters were comparing that to Philosophy -> logic -> dialectic (argument logic).
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Re: A logical argument

Postby Tempus8 on February 24th, 2012, 7:21 am 

Lets not forget about cogency as well :-)
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Re: A logical argument

Postby flannel jesus on February 24th, 2012, 7:27 am 

Fredd wrote:
Benzie wrote:
Isn't mathematics surely a branch of logic?


Yes, that's the usual classification.

"Today, logic is both a branch of mathematics and a branch of philosophy." http://plato.stanford.edu/entries/logic-classical/

He asked if math was a branch of logic.
You said yes, but then you said that logic is a branch of math.
If logic is a branch of math, then the correct answer is "no."
Branching doesn't work both ways.

You say the branch is a branch of a tree, but you can't reverse that and say that the tree is a branch of the branch. Branching works from bigger to smaller only.
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Re: A logical argument

Postby Fredd on February 24th, 2012, 4:00 pm 

flannel jesus wrote:
Fredd wrote:
Benzie wrote:
Isn't mathematics surely a branch of logic?


Yes, that's the usual classification.

"Today, logic is both a branch of mathematics and a branch of philosophy." http://plato.stanford.edu/entries/logic-classical/ <unsnip> I liked that explanation for where I thought the exchange was leading, so adopted its terminology.

He asked if math was a branch of logic.
You said yes, but then you said that logic is a branch of math.
If logic is a branch of math, then the correct answer is "no."
Branching doesn't work both ways.


Yes, my error. It depends on context, but I should have set the link's context before using its terminology. Since I'm trying to learn about "universe of discourse," suppose I had set it this way:

For all curricula referred to as "logic" in nearly all math or philosophy departments," logic is both a branch of math and a branch of philosophy.

Did I do that right? Is "nearly all" acceptable in a statement of "universe of discourse?"

Personally, I don't like their "branch of" terminology even given the context. I always use "logic of..." like "logic of math" or "logic of science" or "logic of stamp collecting." I think most people are comfortable with that.

<snip>
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