Falsafah dan Isu Semasa (ENGLISH) - Logic

PHILOSOPHY &
CURRENT ISSUES
Topic 3: Logic
By Fadhilah Raihan Lokman
SLAS, Taylor’s University

Learning Outcome
Explain the role, position
and relationship of
Logical Science with
Philosophy
Explain various errors in
thinking and
argumentation or
Fallacy
Describe the
development, uses and
differences of the two
main approaches in
Logic namely Deduction
and Induction
Describe the various
types of methodologies
that enrich the
development of more
complex knowledge
Fadhilah Raihan Lokman

ROLE OF LOGIC &
PREVENTION OF
FALLACIES (ERROR
IN THINKING)

INTRODUCTION TO LOGIC
Meaning of Logic
• From the Greek "logos", with a variety of meanings including word, thought,
idea, argument, account, reason or principle, discussion, intellect
It is the study of reasoning, or the study of the principles and
criteria of valid inference and demonstration
• It attempts to distinguish good reasoning from bad reasoning
• It demands that all activities corresponding to man’s line of thinking must be
correct
But the correctness or incorrectness of thinking is not the sole
concern of logic but also the rules and guidelines that go with it

INTRODUCTION TO LOGIC
Individuals who learn and practice these principles of
logic are more likely to be able to argue properly and
reason correctly than those who do not learn them.
Yet, that does not rule out the possibility that
individuals who have not studied logic can also argue
reasonably.
Fundamentally, the aim of logic is the elaboration of a
coherent system that allows us to investigate, classify,
and evaluate good and bad forms of reasoning.

HOW SCHOLARS DEFINE LOGIC
Cruz,
1995
• Generally,
Logic is
understood
as the
science and
art of correct
thinking Gualdo,
2000
• Logic as an
art, it guides
man’s
reasoning so
he can proceed
with order and
ease and
without error in
the constructive
activity of
making
definitions of
terms,
propositions
and inferences.
McCall,
1971
• Logic as a
speculative
science, is
concerned
primarily with
what is correct
reasoning and
why it is
correct.
Bachelor,
1966
• Logic is the
science and art
of correct
thinking

Logic is the study of an argument consists of
premise and conclusion
Arguments consist of a sequence of premises
in which a conclusion is attempted to be made
from the premise of the premise
• Premise 1: All human beings will die (p1)
• Premise 2: I am human (p2)
• Conclusion: I will die (c)

ARGUMENT
Arguments are not the same as opinions.
An argument contains a sequence of statements in
which one of the statements is a conclusion drawn.
A proposition is an assertion, or a proposition or a
declaration in a statement whether true or false.
If all the premises are true, and the conclusions
drawn are true, then the argument is valid.
P1 P2 C

Logic is not
a matter of
opinion:
When it comes to evaluating
arguments, there are specific
principles and criteria that you
should use.
If you use those principles and
criteria, then you are using logic; if
you aren’t, then you are not justified
in claiming to use logic or be logical.
This is important because
sometimes people don’t realize that
what sounds reasonable isn’t
necessarily logical.
This reasoning process—using
principals of logic in your reasoning,
thinking, and arguments—is critical
to the practice of philosophy.

Deductive
Logic
Inductive
Logic
Abductive
Logic
Heuristic
Logic
LOGICAL REASONING

DEDUCTIVE LOGIC
Deductive reasoning concerns what follows necessarily from given
premises that is from a general premise to a particular one.
It is a process of reasoning from one or more statements (premises)
to reach a logical conclusion.
However, it should be remembered that a false premise can possibly
lead to a false conclusion.
Having said that, if all premises are true, the terms are clear, and the
rules of deductive logic are followed, then the conclusion reached is
necessarily true.

OTHER TERMS OF DEDUCTIVE LOGIC
Qiyas
Arabic qiyās, in Islamic
law, analogical reasoning
as applied to the deduction
of juridical principles from
the Quran and the Sunnah
(the normative practice of
the community).
In some cases, ijmāʿ
legitimized a solution or
resolved a problem. Very
often, however, qiyas was
used to deduce new beliefs
and practices on the basis
of analogy with past
practices and beliefs. Syllogism
A form of reasoning in
which a conclusion is
drawn from two given or
assumed propositions
(premises)
In a syllogism, the more
general premise is called
the major premise. The
more specific premise is
called the minor premise.

Example:
P1: All spiders have eight
legs.
P2: A tarantula is a spider.
Conclusion: Therefore,
tarantulas have eight legs
Formula:
P1: All P is Q
P2: S is P
Conclusion: Therefore, S is Q
• Based on the above example, if we accept premise 1 and premise 2 as
true and valid, then we cannot reject the conclusion or the result.
• This is because the resulting result is according to the premises with
certainty.
• If every premise is true, and its structure is correct, then the result is also
certainly true and valid

Example:
P1: All cows are blue in color.
P2: Socrates is a cow.
Conclusion: Therefore, Socrates is blue in color.
In the deductive method of thinking, the most important thing to
emphasize is adherence to two main conditions:
1) All premises must be true
2) The structure must be correct
However, some deductive arguments are still considered valid
even if the premises are not true. For example, the deductive
thinking below has the correct premise structure, hence the result
produced is valid even if it is not true.

Wrong Formula:
P1: All P is Q
P2: S is Q
C: Therefore, S is P
Example:
P1: All philosophers are wise.
P2: Abu is a wise person.
Conclusion: Therefore, Abu is a philosopher.
A valid deductive thinking methods must adhere to a correct
premise structure.
When the premises are not arranged in a valid form, even if the
premise is true, the result or conclusion drawn will still be
erroneous, untrue and invalid.

INDUCTIVE LOGIC
Inductive reasoning is the process of deriving a reliable generalization from
observations (i.e., from the particular to the general).
The premises of an argument are believed to support the conclusion, but do not
necessarily ensure it.
Basically, inductive is used to describe reasoning that involves using specific
observations, such as observed patterns, to make a general conclusion.
Inductive logic is not concerned with validity or conclusiveness, but with the
soundness of those inferences for which the evidence is not conclusive.

Example:
Ali found Sofiah, Ahmad dan few of his friends from
Kelantan enjoy sweet food. Ali comes to the
conclusion that all Kelantanese enjoy sweet food.
The conclusion about all Kelantanese enjoy sweet
foods is true but at the same time it is probable.
There is a possibility that there are Kelantanese
who do not like sweet food that Ali has not known.
In most situations, the inductive method is only
able to give a probable result because it is
impossible for Ali to know all the people of
Kelantan.

DEDUCTION INDUCTION
• Arguments in which obligatory
conclusions are drawn from the premise.
• Specific conclusions are drawn from
general statements
• Arguments in which a conclusion
appears likely to be drawn from the
premise.
• General conclusions are drawn from
specific statements
Premise 1: All human beings will die
Premise 2: I am a human being.
Conclusion: So, I'm going to die
Premise 1: 90% of UoA students are not
proficient in English
Premise 2: Alex is a UoA student
Premise 3: Therefore, Alex may not be
proficient in English
COMPARISON: DEDUCTIVE V. INDUCTIVE

CLASS ACTIVITY
Give one example
of deductive and
inductive argument
each.
Link:
https://padlet.com/dhiraiyhan
/logic

OTHER APPROACHES OF
LOGICAL REASONING

ABDUCTIVE LOGIC
Abductive reasoning is to abduce (or take away) a logical assumption, explanation, inference,
conclusion, hypothesis, or best guess from an observation or set of observations.
Because the conclusion is merely a best guess, the conclusion that is drawn may or may not
be true.
From there a conclusion is made about what happened before the existence of the
phenomenon which can explain why the phenomenon exists or occurs.
That is, we try to give the best explanation based on the phenomenon that exists. In this case
we think by thinking backwards or thinking backwards.

EXAMPLES OF
ABDUCTIVE METHOD
You have a cough, a fever of 101 degrees
Fahrenheit, a runny nose, chills, an aching body,
nausea and diarrhea. You have had these
symptoms for five days. Given this information,
your best guess is that you have influenza, or the
flu. But you are not completely certain.
If you hear birdsong
outside your window and
you may conclude that a
bird is probably nearby.

HEURISTIC LOGIC
A heuristic is a mental shortcut that allows people to solve problems and make judgments
quickly and efficiently. These rule-of-thumb strategies shorten decision-making time and allow
people to function without constantly stopping to think about their next course of action.
Heuristic methods are not a formal problem-solving method as they do not have systematic or
orderly rules that can be applied as in deductive and inductive logic.
Heuristic thinking is exploratory; It is not of an evaluation nature as found in deductive and
inductive logic where the method of logic is used to evaluate whether an argument or
proposition or the argument can be accepted as valid or invalid.
Although this heuristic logic does not have specific rules yet there are guidelines to implement
heuristic thinking.

HEURISTIC LOGIC
Relying only heuristics to solve a problem works well
as a quick fix or when the alternative solution is
impractical – it may cost too much, be unusable in
the current environment, or be a long-term project.
They can also be used as part of creative problem-
solving techniques but should only be used as one of
the ways to generate ideas or overcome a barrier.
Trial and
error
A rule of
thumb
An educated
guess
An intuitive
judgment
Stereotyping Profiling
Common
sense

EXAMPLE OF
HEURISTIC METHOD
For example, when trying to decide if
you should drive or ride the bus to
work, you might suddenly remember
that there is road construction along
the bus route.
You realize that this might slow the bus
and cause you to be late for work. So,
you leave earlier and drive to work on
an alternate route.

WHAT IS FALLACIES?
Logical fallacies are flawed, deceptive, or false
arguments that can be proven wrong with reasoning.
Fallacies are common errors in reasoning that will
undermine the logic of your argument.
Fallacies can be either illegitimate arguments or
irrelevant points and are often identified because
they lack evidence that supports their claim.
Avoid these common fallacies in your own arguments
and watch for them in the arguments of others.

CORRECT & DEFECTIVE
ARGUMENT FORMS
In logic an argument consists of a set of statements, the premises, whose
truth supposedly supports the truth of a single statement called the
conclusion of the argument.
An argument is deductively valid when the truth of the premises guarantees
the truth of the conclusion; i.e., the conclusion must be true, because of the
form of the argument, whenever the premises are true.
Some arguments that fail to be deductively valid are acceptable on grounds
other than formal logic, and their conclusions are supported with less than
logical necessity. In other potentially persuasive arguments, the premises
give no rational grounds for accepting the conclusion. These defective
forms of argument are called fallacies.

False arguments are used to misled or
influence people to belief it is true.
Functional logic distinguishes a faltering
argument from a valid argument.
What are factors of fallacy in life?
Insufficient
data/facts
Prejudiced
and
pessimistic
Deviant
conclusions
False
assumptions
Emotional
stress
Force

TYPES OF FALLACY
Formal
A formal fallacy is a defect in
the structure of an argument
In other words, the conclusion
doesn't follow from the
premises
Example:
• P1 All cats are animals
• P2 All dogs are animals
• C Therefore, all cats are
dogs
Informal
An informal fallacy is a defect in
the content of an argument
Arguments that have incorrect
or irrelevant premises
Example (ad homihem):
• P1 I’m the senior
• P2 You are the junior
• C Therefore, you have no
rights to tell me what to do!

VARIOUS TYPES OF
INFORMAL FALLACIES
Hasty Generalization
•A claim based on a few
examples rather than
substantial proof.
•Arguments based on hasty
generalizations often don't
hold up due to a lack of
supporting evidence: The
claim might be true in one
case, but that doesn't mean
it's always true.
Example: My roommate said
her philosophy class was
hard, and the one I'm in is
hard, too.
Ad Homihem
•It uses personal attacks
rather than logic.
•This fallacy occurs when
someone rejects or criticizes
another point of view based
on the personal
characteristics, ethnic
background, physical
appearance, or other non-
relevant traits of the person
who holds it.
Example: A parent who says
that the teacher doesn't
know how to teach because
she graduated from a
community college.
Strawman
•A straw man argument
attacks a different subject
rather than the topic being
discussed — often a more
extreme version of the
counter argument.
•The purpose of this
misdirection is to make one's
position look stronger than it
actually is.
Example: I think that we
should give better study
guides to students”, “I think
that your idea is bad,
because we shouldn’t just
give out easy As to
everyone”

VARIOUS TYPES OF
INFORMAL FALLACIES
Red Hering
• Argument that diverts
attention from the real
issue by focusing
instead on an issue
having only a surface
relevance to the first.
Example: Son: "Wow,
Dad, it's really hard to
make a living on my
salary." Father:
"Consider yourself
lucky, son. Why, when I
was your age, I only
made $40 a week."
Faulty Cause & Effect
• This fallacy falsely
assumes that one
event causes another.
Often a reader will
mistake a time
connection for a cause-
effect connection.
Example: Every time I
wash my car, it rains.
Appeal to Emotion
• This is used to sway
the emotions of an
audience to make them
support the speaker's
argument.
Example: “I'm sorry
officer, my family is
very poor, and I haven't
eaten in days.”

CLASS ACTIVITY
In your opinion,
why it matters to
think logically and
to be able to
identify fallacy in
arguments?

CONCLUSION
• This topic invites students to understand the methods to think correctly through
logic.
• The ability to discern a valid argument from a false one is an important skill. It's a
key aspect of critical thinking and it can help you to avoid falling prey to fake
news.
• If you're taken in by a logical fallacy, false conclusions might cause you to make
decisions that you later regret.

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