## User Tag List

1. Originally Posted by ragashree
Many Now the question is, which one is most pertinent?
The most pertinent is the fact that at each branch or question a path is assumed to be the most pertinent

2. There is the notion of a set of elements.

{} is the set containing nothing. {bka, pha} is the set containing bka, and pha. A rigorous development is beyond the scope of a single post.

{{x},{x,y}} is the set containing {x} (which is in turn a set containing x) and {x,y} (which is in turn a set containing {x,y}).

A short form of writing {{x},{x,y}} is (x,y) and is called an ordered pair.

A set containing ordered pair is a binary relation. If R is a binary relation, {x|(x,y) in R} is called the domain of R and {y|(x,y) in R} is called the Range of a R. If for every x in the domain of R there is exactly one y in the range of R such that (x,y) is in R, then R is a '1-to-1' correspondence.

If the following three things are true of a relation of R, then R is an "equivalence relation":
1) (x,x) is in R
2) if (x,y) is in R, then (y,x) is in R
3) if (x,y) is in R and (y,x) is in R, then (x,z) is in R

The 0 is often short hand for {}. The 'successor' of a set, S, is the set containing S and the contents of S. The successor of 0 is {{}} also often known as 1. The successor of 1 is {{{}},{}} also often known as 2. You could continue on this way. The sets defined this way are the "whole numbers."

The number of objects in a set is defined to be the whole number to which you can create a 1-to-1 correspondence.

Now imagine that there is a set S, and binary relation, A1, consisting of ordered pairs of the form ((a,b),c), where a, b, and c are elements of S. Consider further the binary relation A2 which is {(c,(a,b))|((a,b),c) is in A1}, and yet another binary relation A3 consisting ordered pairs of the form (e,f) where e and f are from S. If the union of A1, A2, and A3 forms an equivalence relation, then A1 and A3 form a basis for an "addition" of sorts (consider modulo arithmetic for instance).

It is often customary to use the whole numbers as S, A1 with the following properties:
1) (({},{}),{}) is in A1
2) if ((a,b),c) is in A1, then ((successor of a, b),successor of c) is in A1
3) if ((a,b),c) is in A1, then ((a, successor of b),successor of c) is in A1
and A3 being {(x,x)| x is a whole number}

You can check that the appropriate equivalence relation holds.

You could then introduce '+' as notation so that a+b=c means ((a,b),c) is in A1.

Obviously, I can't make all this rigorous in one post. But hopefully it gives you some idea how mathematicians "built-up" addition conceptually from sets.

To unravel all this for 2+2:

We look for the appropriate element in the set of the form (({{{}},{}},{{{}},{}}),c) in A1.
Let us build up. (({},{}),{}) is in A1. So (({{}},{}),{{}}) is in A1. Which in turn means, (({{}},{{}}),{{{}},{}}) is in A1. This then means (({{{}},{}},{{}}),{{{{}},{}},{{}},{}}). Note {{{{}},{}},{{}},{}} is often referred as 3 and is the successor of 2 which is {{{}},{}}. Finally, we arrive at what we are looking for in that (({{{}},{}},{{{}},{}}),{{{{{}},{}},{{}},{}},{{{}}, {}},{{}},{}}) is in A1. {{{{{}},{}},{{}},{}},{{{}},{}},{{}},{}} is often refered to as 4.

3. 2+2=5

Did the black hole suck us in yet?

4. Originally Posted by ygolo
There is the notion of a set of elements.

{} is the set containing nothing. {bka, pha} is the set containing bka, and pha. A rigorous development is beyond the scope of a single post.

{{x},{x,y}} is the set containing {x} (which is in turn a set containing x) and {x,y} (which is in turn a set containing {x,y}).

A short form of writing {{x},{x,y}} is (x,y) and is called an ordered pair.

A set containing ordered pair is a binary relation. If R is a binary relation, {x|(x,y) in R} is called the domain of R and {y|(x,y) in R} is called the Range of a R. If for every x in the domain of R there is exactly one y in the range of R such that (x,y) is in R, then R is a '1-to-1' correspondence.

If the following three things are true of a relation of R, then R is an "equivalence relation":
1) (x,x) is in R
2) if (x,y) is in R, then (y,x) is in R
3) if (x,y) is in R and (y,x) is in R, then (x,z) is in R

The 0 is often short hand for {}. The 'successor' of a set, S, is the set containing S and the contents of S. The successor of 0 is {{}} also often known as 1. The successor of 1 is {{{}},{}} also often known as 2. You could continue on this way. The sets defined this way are the "whole numbers."

The number of objects in a set is defined to be the whole number to which you can create a 1-to-1 correspondence.

Now imagine that there is a set S, and binary relation, A1, consisting of ordered pairs of the form ((a,b),c), where a, b, and c are elements of S. Consider further the binary relation A2 which is {(c,(a,b))|((a,b),c) is in A1}, and yet another binary relation A3 consisting ordered pairs of the form (e,f) where e and f are from S. If the union of A1, A2, and A3 forms an equivalence relation, then A1 and A3 form a basis for an "addition" of sorts (consider modulo arithmetic for instance).

It is often customary to use the whole numbers as S, A1 with the following properties:
1) (({},{}),{}) is in A1
2) if ((a,b),c) is in A1, then ((successor of a, b),successor of c) is in A1
3) if ((a,b),c) is in A1, then ((a, successor of b),successor of c) is in A1
and A3 being {(x,x)| x is a whole number}

You can check that the appropriate equivalence relation holds.

You could then introduce '+' as notation so that a+b=c means ((a,b),c) is in A1.

Obviously, I can't make all this rigorous in one post. But hopefully it gives you some idea how mathematicians "built-up" addition conceptually from sets.

To unravel all this for 2+2:

We look for the appropriate element in the set of the form (({{{}},{}},{{{}},{}}),c) in A1.
Let us build up. (({},{}),{}) is in A1. So (({{}},{}),{{}}) is in A1. Which in turn means, (({{}},{{}}),{{{}},{}}) is in A1. This then means (({{{}},{}},{{}}),{{{{}},{}},{{}},{}}). Note {{{{}},{}},{{}},{}} is often referred as 3 and is the successor of 2 which is {{{}},{}}. Finally, we arrive at what we are looking for in that (({{{}},{}},{{{}},{}}),{{{{{}},{}},{{}},{}},{{{}}, {}},{{}},{}}) is in A1. {{{{{}},{}},{{}},{}},{{{}},{}},{{}},{}} is often refered to as 4.
I am more about philosophical logic, not calculus logic

5. Originally Posted by ygolo
There is the notion of a set of elements.

{} is the set containing nothing. {bka, pha} is the set containing bka, and pha. A rigorous development is beyond the scope of a single post.

{{x},{x,y}} is the set containing {x} (which is in turn a set containing x) and {x,y} (which is in turn a set containing {x,y}).

A short form of writing {{x},{x,y}} is (x,y) and is called an ordered pair.

A set containing ordered pair is a binary relation. If R is a binary relation, {x|(x,y) in R} is called the domain of R and {y|(x,y) in R} is called the Range of a R. If for every x in the domain of R there is exactly one y in the range of R such that (x,y) is in R, then R is a '1-to-1' correspondence.

If the following three things are true of a relation of R, then R is an "equivalence relation":
1) (x,x) is in R
2) if (x,y) is in R, then (y,x) is in R
3) if (x,y) is in R and (y,x) is in R, then (x,z) is in R

The 0 is often short hand for {}. The 'successor' of a set, S, is the set containing S and the contents of S. The successor of 0 is {{}} also often known as 1. The successor of 1 is {{{}},{}} also often known as 2. You could continue on this way. The sets defined this way are the "whole numbers."

The number of objects in a set is defined to be the whole number to which you can create a 1-to-1 correspondence.

Now imagine that there is a set S, and binary relation, A1, consisting of ordered pairs of the form ((a,b),c), where a, b, and c are elements of S. Consider further the binary relation A2 which is {(c,(a,b))|((a,b),c) is in A1}, and yet another binary relation A3 consisting ordered pairs of the form (e,f) where e and f are from S. If the union of A1, A2, and A3 forms an equivalence relation, then A1 and A3 form a basis for an "addition" of sorts (consider modulo arithmetic for instance).

It is often customary to use the whole numbers as S, A1 with the following properties:
1) (({},{}),{}) is in A1
2) if ((a,b),c) is in A1, then ((successor of a, b),successor of c) is in A1
3) if ((a,b),c) is in A1, then ((a, successor of b),successor of c) is in A1
and A3 being {(x,x)| x is a whole number}

You can check that the appropriate equivalence relation holds.

You could then introduce '+' as notation so that a+b=c means ((a,b),c) is in A1.

Obviously, I can't make all this rigorous in one post. But hopefully it gives you some idea how mathematicians "built-up" addition conceptually from sets.

To unravel all this for 2+2:

We look for the appropriate element in the set of the form (({{{}},{}},{{{}},{}}),c) in A1.
Let us build up. (({},{}),{}) is in A1. So (({{}},{}),{{}}) is in A1. Which in turn means, (({{}},{{}}),{{{}},{}}) is in A1. This then means (({{{}},{}},{{}}),{{{{}},{}},{{}},{}}). Note {{{{}},{}},{{}},{}} is often referred as 3 and is the successor of 2 which is {{{}},{}}. Finally, we arrive at what we are looking for in that (({{{}},{}},{{{}},{}}),{{{{{}},{}},{{}},{}},{{{}}, {}},{{}},{}}) is in A1. {{{{{}},{}},{{}},{}},{{{}},{}},{{}},{}} is often refered to as 4.
TL;DR LOLZ. How long did that take you to do? *Just joking, just joking*

6. 2 + 2 = 1

Two piles of sand plus two piles of sand equals one pile of sand.

(One must consider units to get a meaningful result.)

7. Originally Posted by Coriolis
2 + 2 = 1

Two piles of sand plus two piles of sand equals one pile of sand.

(One must consider units to get a meaningful result.)
2 piles of sand + 2 piles of sand = 4 combined piles of sand.

8. Originally Posted by poki
I am more about philosophical logic, not calculus logic
Formal reasoning is formal reasoning, whether you learn it in philosophy or in math. I believe math teaches it better, personally.

Originally Posted by Little_Sticks
TL;DR LOLZ. How long did that take you to do? *Just joking, just joking*
Actually not very long. I didn't try to make it rigorous, just show one possible mathematical definition for 2+2.

Most mathematicians and computer scientists who have studied sets could do a similar explanation in a few minutes.

9. This question isn't easy. LIES!

10. Originally Posted by ygolo
Formal reasoning is formal reasoning, whether you learn it in philosophy or in math. I believe math teaches it better, personally.
Philosophical Logic

From wiki:
Philosophical logic

Philosophical logic deals with formal descriptions of natural language. Most philosophers assume that the bulk of "normal" proper reasoning can be captured by logic, if one can find the right method for translating ordinary language into that logic. Philosophical logic is essentially a continuation of the traditional discipline that was called "Logic" before the invention of mathematical logic. Philosophical logic has a much greater concern with the connection between natural language and logic. As a result, philosophical logicians have contributed a great deal to the development of non-standard logics (e.g., free logics, tense logics) as well as various extensions of classical logic (e.g., modal logics), and non-standard semantics for such logics (e.g., Kripke's technique of supervaluations in the semantics of logic).

Logic and the philosophy of language are closely related. Philosophy of language has to do with the study of how our language engages and interacts with our thinking. Logic has an immediate impact on other areas of study. Studying logic and the relationship between logic and ordinary speech can help a person better structure his own arguments and critique the arguments of others. Many popular arguments are filled with errors because so many people are untrained in logic and unaware of how to formulate an argument correctly.
To the bolded. I dont study the relationship between logic and speech. I study the speech itself and the logistics within the speech. This is how I listen and understand. What I do goes beyond if X then Y, or If not A then not B. Its not mathematical logic. I dont study logic, I practice logic.

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