These are formal ways of determining the validity of your argument.

A deductively valid argument means that IF the premises are true THEN the conclusion MUST BE true.

An inductively valid argument means that IF the premises are true THEN its conclusion is MORE PROBABLE THAN NOT

A little vocabulary for you: An inclusive OR is one that means you can have A, B, or both A and B; and exclusive OR means that you can have either A, or B, but not both. A syllogism is a pattern of reasoning. A conjuction is an AND statement, a disjunction is an OR statement.

I'll try to give examples as we move along.

DEDUCTIVELY VALID ARGUMENTS

Affirming the Antecedent (Modus Ponens)

IF P, THEN Q

IF I am right, THEN you are wrong

P

I am right

Q

You are wrong

Denying The Concequent (Modus Tollens)

IF P, THEN Q

IF it is raining, THEN I need an umbrella

NOT Q

It is not raining

NOT P

I do not need an umbrella

Hypothetical Syllogism (Chain Reasoning)

IF P, THEN Q

IF you fall, THEN you will hit the ground

IF Q, THEN R

IF you hit the ground, THEN you will scrape your knee

IF P, THEN R

IF you fall, THEN you will scrape your knee

Disjunctive Syllogism - This utilizes the use of an inclusive OR

P OR Q

Either you have milk OR eggs

NOT P

You DONT have milk

Q

Therefore, you have eggs

Conjunctive Syllogism

NOT BOTH P AND Q

It can't be raining AND not raining

P

It is raining

NOT Q

It's not raining

Inductively Valid Arguments (Fallacious)

Affirming the Consequent

IF P, THEN Q

IF Jane leaves Tommy, THEN Tommy will commit suicide

Q

Tommy commited suicide

P

Jane left Tommy

Denying the Antecedent

IF P, THEN Q

IF you scrape your knee, THEN you fell

NOT P

You did not scrape your knee

NOT Q

You did not fall

Fallacy of Omitting the IF

IF P, THEN Q
IF Q, THEN R
R

False Disjunctive Syllogism - This utilizes the exclusive OR

P OR Q

You need eggs OR milk

P

You have eggs

NOT Q

You don't need milk

False Conjunctive Syllogism

NOT BOTH P AND Q
NOT P
Q


If there are any questions/comments, I'll answer them here.

You're a cutie , Where'd you learn this? I learned most of this last year in English class

Originally Posted by S for Shoota

You're a cutie , Where'd you learn this? I learned most of this last year in English class

I learned this last year in my Critical Thinking course. This is only the introduction though, there's lots more to be learned about logic.

If you really wanna scramble your brains, take a look at truth tables.

Originally Posted by NiceGuy

I learned this last year in my Critical Thinking course. This is only the introduction though, there's lots more to be learned about logic.

If you really wanna scramble your brains, take a look at truth tables.

, Where at? I'm up for a little scramblin......

These kinds of things interest me, Critical Thinking is a college course?

im a cutie too .... well now we all have something to whipe out during a forums argument, thanks!

Originally Posted by S for Shoota

, Where at? I'm up for a little scramblin......

These kinds of things interest me, Critical Thinking is a college course?

Yeah, I took it in college. Probably the best class I've taken so far -- really makes you think (oh the irony!)

Here you go; wrap your brain around this:

http://www.math.csusb.edu/notes/logic/lognot/node1.html

Originally Posted by NiceGuy

Yeah, I took it in college. Probably the best class I've taken so far -- really makes you think (oh the irony!)

Here you go; wrap your brain around this:

http://www.math.csusb.edu/notes/logic/lognot/node1.html

I think most people would be surprised at how much math really plays a role in their line of thought (err...mentally stable people, anyway). Rational conclusions come from looking at something either deductively and/or deductively (as you so eloquently showed us), and oh yes, thoe ideologies do indeed relate to mathematics. Many people are also surprised that they have to go to a math building to take a logic course. They think it's just philosophy or something.

Originally Posted by NiceGuy

Yeah, I took it in college. Probably the best class I've taken so far -- really makes you think (oh the irony!)

Here you go; wrap your brain around this:

http://www.math.csusb.edu/notes/logic/lognot/node1.html

Holy Jesus Christ On ICE!

Its pretty interesting.....I'll look into that next year when I go off to college!!!

Thanks for this Niceguy....you're a Nice Guy

Originally Posted by S for Shoota

Holy Jesus Christ On ICE!

Its pretty interesting.....I'll look into that next year when I go off to college!!!

Thanks for this Niceguy....you're a Nice Guy

That's what they say.

Really, Critical thinking is a valuable course. I want to get it implimented into the high school level.