Logic

1. ROSIELYN MAE TAN BOLON
III-13HC BSE ENGLISH

2. When do you say that someone/
something is logical or illogical?

3. What is Logic, then?

4. 
Logic is the study of methods and
principles used to distinguish correct
reasoning from incorrect reasoning
(Cohen )
 Science and art of correct thinking

5. Goals of Logic
A. Identify good arguments
B. To be able to make good
arguments

6. Types of Logic (form and
content)
1. Formal Logic
-about aspect of
forms, structures, sequences and
the following of the rules
e.g. Life is a matter of choice.
(what’s the subj.?verb?pred.?...)

7. 2. Material Logic
concerned with subject
matter, content and function
*Why and how is life a matter of
choice?

8. Types of Logic (Process of
thinking)
1. Deductive Logic
universal to particular;
general to specific

9. e.g.
All III-13 students are pretty.
Agatha belongs to III-13
Therefore, Agatha is pretty.

10. 2. Inductive Logic
 particular to
universal, specific to general

11. e.g.
The mango falls, the book, the
pen…
Therefore, bodily objects fall.

12. 1. Simple Apprehension
-process of grasping the
objective reality where
concept/idea is formed and
expensed in terms.

13. - The act by which the mind grasps or lays
hold of an object, without affirming or
denying anything about it
- (L) Apprehendere: become aware
of, recognize or contemplate and object

14.  When I understand what is meant by
“triangle”, “man”, and “stupid”, this
understanding is a simple apprehension

15. 1
•SENSE
2
•SENSE DATA
3
•PERCEPTION
4
• CONCEPT/ IDEA

16. 2. Judgment
- assertion or denial of something in
case after all the available/needed
ideas are organized and analyzed.
Proposition is used in expressing
judgment

17.  Simple apprehension +
affirmation/denial = Judgment

18. E.g.
 The triangle is an isosceles triangle.
 This man is stupid.
 Every changing being is imperfect.

19.  Simple apprehension => concept or mental
word : judgment=> mental statement*
* Representations formed in by the mind

20. Things to consider in making
judgment:
1. All ideas involved are to be understood
2. Each ideas is to be contrasted/compared
with the other ideas.
3. Ideas compared are to be judged as to
whether in agreement or in agreement.
4. Judgment is expressed as propositions.
5. Judgment is based on inferences.

21. Logical Truth and Falsity of
Judgment
 A judgment is true when real relationship
of two ideas/realities being compared is
established or in agreement
 And false if relationship is not established
and not in agreement

22. Convince Me Why!
 Is death penalty justified?
 Is the Philippines a progressive
country?
 Should divorce be allowed in the
Philippines?

23. 3. Reasoning
 Process with which one advances from
premises to conclusion to prove something
1
Inferences
2
Judgment
3
Conclusion

24. Proposition (Cohen) –assertions that are
either true or false and stated in
declarative form; written or spoken
expression of the mental statement
e.g. This is a dog. The animal is not a cat.

25.  Argument, Premise and Conclusion
1. Argument- group of propositions of which
one follows the others to provide support on
ground for the truth of that one
2. Premise- a proposition or inference in an
argument
3. Conclusion- an affirmed argument

26. Examples of Premise and
Conclusion
1. No one was present when life first appeared
on earth. Therefore, any statement about
life’s origin should be considered a myth.
2. Since all humans come from a small number
of African ancestors, believing in different
races is ridiculous.
3. Cigarette selling should stop. After
all, cigarette is the leading cause of death.

27.  Arguments are acts of reasoning
 In reasoning, the known truths are related to
new truth(premise) to form
conclusions(resulting to truth)

28. Two Principle of Reasoning
 Principle of Non-Contradiction
an object cannot be true and false at the same
time.
e.g. The chalk is white and non-white.
You are beautiful and ugly.

29.  Principle of Excluded Middle
every predicate can either be truly
affirmed or truly denied of every subject