logic: as tool of philosophy

Science of correct reasoning1. Nature of man: correct

thinking2. To examine our ability

to adapt: in difficult or

controversial cases.3. Organizing

ideas/arguments: expressing them with

more accuracy drawing legitimate

conclusions.

Logic: as tool of Philosophy

FORMAL LOGIC1. CORRECTNESS RATHER

THAN THE TRUTH Has to do with correctness or

sequence or the following of rules.

2. Not on the material content of the argument.

3. To reason correctly is not necessarily the same as to reason truthfully.

FORMAL & MATERIAL LOGIC

E.g. Formal Logic:

Practice makes perfect

Nobody is perfect

Why practice?

Pag sumama ka sa matalino, tatalino ka rin!

Pag sumama ka sa adik, magiging adik ka rin!

Try mo sumama sa AKIN…

Baka maging AKIN ka rin!

MATERIAL LOGIC1. Concerned with

the truth2. thought-contents

is in correspondence with reality

Connection: mind & real order

E.g. Material Logic

The human soul is endowed with intellect and will;

But, what is endowed with intellect and will is spiritual;

Ergo, the human soul is spiritual.

Potential recruits of Mass Media Industry are students who completed their course in Communication.

I’ve successfully completed my course in Communication last March of 2010.

I am therefore qualified to be a recruit of the Mass Media Industry.

Nature of an argumentArgument is an inferential thinking that is composed of conclusion and premise (assertion/statement) from which the conclusion is inferred.

Inferential: the process of reasoning from a premise to a conclusion; in which the conclusion is drawn from evidential reasoning.

Arguments

E.g. Premise 1: anything that moves is moved by another;

Premise 2: but, the ball moves

Conclusion: therefore, the ball is moved by another.

INFERENTIAL?

PREMISES

CONCLUSION

CLAIMED EVIDENCE

WHAT IS CLAIMED TO FOLLOW FROM THE

EVIDENCE

Valid: (T-T) INFERENTIAL1.The conclusion is true

because of the true premises.

2.It is impossible that the premises of an argument are true and the conclusion false

VALID & INVALID ARGUMENTS

E.g.1.  All chickboys have

multiple partners/girlfriends. 

2.  Ysmael & Iggy Boy have 10 girlfriends each at the same time. 

__________________________3.  Therefore, Ysmael & Iggy

Boy are both chickboys.

VALID ARGUMENTS

1.  All people who are born in the United States are U.S. citizens. 

2.  Tutoy was born in the United States. 

____________________3.  Therefore, Tutoy is a U.S. citizen. 

VALID ARGUMENTS

1.  All mammals have kidneys.

2.  Plants do not have kidneys.

____________________3.  Therefore, plants are not mammals. 

VALID ARGUMENTS

T-FThe premises are true and

the conclusion is false.fallacy of affirming the

consequent.“Inductive: assuming”

“not necessarily… probably!”

(+) If it rains, then the ground gets wet.

(+) But, the ground is wet; (-) Therefore, it rained.

INVALID ARGUMENTS (PRESUMPTUOUS)

1.  If Arn-Arn is in Hollywood, then he is in California.

2.  Arn-Arn is in California.

______________________3. Therefore, Arn-Arn is in Hollywood. 

INVALID ARGUMENTS

1.  Horses are not reptiles.

2.  Mr. Diego is not a reptile.

_________________3.  Therefore, Mr. Diego is a horse. 

INVALID ARGUMENTS

“masarap magmahal,

nagmamahal ako, samakatuwid…

masarap ako!”

God is love, but love is blind. Therefore, God is blind!”

F-FThe premises are false (NOT

MATERIAL) and it follows that the conclusion is false(NOT MATERIAL!)

It is valid because: the way in which the premises and conclusion are structured is “FORMALLY CORRECT!”

ALL TREES ARE WOMENBUT, ALL MEN ARE TREESTHEREFORE, ALL WOMEN

ARE MEN

VALID YET ABSURD

One premise: false/trueConclusion: true

(accidental)E.g.

(+) All dogs are animal;

(-) But, all cats are dogs;

(+) Therefore, all cats are animals.

VALID: UNSOUND

VALID ARGUMENTS

PREMISE 1 PREMISE 2 CONCLUSION

VALID/SOUND TRUE (POSITIVE)

TRUE(POSITIVE)

TRUE(POSITIVE)

VALID YET ABSURD

FALSE(NEGATIVE)

FALSE(NEGATIVE)

FALSE(NEGATIVE)

VALID(UNSOUND)

TRUE(POSITIVE)

FALSE(NEGATIVE)

TRUE(POSITIVE)

VALID ARGUMENTS

INVALID ARGUMENTS

PREMISE 1 PREMISE 2 CONCLUSION

INVALID TRUE TRUE FALSE

INVALID ARGUMENTS