Logic Basic Presentation

8/8/2019 Logic Basic Presentation

1/42

Logic

Basic Presentation


2/42

Brief History

Logic as a discipline and an explicit analysis of

the methods of reasoning, was invented by

Aristotle (384-322BC).

He codified the systematic laws of reasoning,

in his collection of works known, named later

the Organon' or instrument.


3/42

Logic is from logos, meaning reason.

The human mind sometimes makes a

mistake in disposition of the premises and

hence arrives at a wrong conclusion.

Logic is in charge of guiding him during the

process of inference.


4/42

Thus, logic is defined as:

: Logic is a legal instrument (organon)

utilizing which protects the mind from

incorrect thinking .


5/42

Logic was first translated into Arabic by

Honayn Ibn Ishaq (810-873AD).

The most celebrated commentator of

Aristotelian logic was Avicenna (Ibn Sina 980-

1037AD); an Iranian Muslim philosopher. His

book is called al-Shifa.


6/42

In the beginning of the 13 th Century the

treaties of Aristotle through the works of

Avicenna and Averroes (Ibn Roshd 1126-

1189AD) were translated into Latin and gave

an immense impetus to western philosophic

study.


7/42

Thinking ' is defined Disposition of the known

statements to gain the unknown one '.

Premise', Argument', Conclusion ':

Every known statement which is used to gain

the unknown statement is called premise' (al-

Moqadamah) and a connected series of


8/42

statements to establish a definite proposition

is called Argument' (al-Hojjah). The unknown

which is known through inference is called

Conclusion' (al-Natijah) .


9/42

Subject of Science

The subject of every science is the essential

properties' of that science. Human's unknown

information is either the Conception', or

Argument' thus the subject of study in logic is

the Definer' (al-Mo'arref), and the Argument'

(al-Hojjah).


10/42

Logic is said to be the most necessary human

knowledge.

Al-Ghazzali; the Muslim theologian (1058-

1111AD); though he was an opponent to

philosophy, considered logic inevitable.

Ibn Taymiyyah and Ibn Qayyem on the other hand

considered studying logic Haram.


11/42

Francis Bacon (1561-1626) and Immanuel Kant

(1724-1804) were also the first opponents of

the Aristotelian logic in western philosophy.


12/42

Definition of Knowledge () :

)14(

The presence of the image of a certain thing

in the mind.

Knowledge in logic is meant for Acquired or

non-presential Knowledge ) ( .


13/42

In acquired knowledge the knower and the

known are different. The Knowledge bridges

them together. Such as our knowledge about

Mecca City.


14/42

Presential Knowledge/knowledge by

presence ) (

Another type of knowledge is knowledge by

presence' in which the actual known is

present to the knower; Such as knowledge

about our emotions. Logic does not deal with

knowledge by presence.


15/42

Types of (Acquired) Knowledge

1. Concept ): ( concept is the simple image of

something in the mind without any judgment

about it.

2. Judgment ):( Judgment is accepting or

rejecting the relation between two concepts.

Every judgment contains three conceptions:


16/42

a) the concept of the subject,

b) the concept of its attribute,

c) the concept of the relation between them


17/42

Divisions of Words

A word either has one or more than one meaning. A

word which has only one meaning is divided into two

types:

particular and universal

Particular = individual )( :

Particular is a word which has only one example

such as: Aristotle, Sydney


18/42

2. Universal )( :

Universal is a word which has more than one

example such as: human being, city.


19/42

If a universal word applies the same to all its

examples is called univocal ')( such

as human being', and if it applies to its

examples in degrees ,)( such as light.


20/42

A word which has more than one meaning is

divided into three types:

1. Homonym )( :

A word which has the same sound and

often the same spelling but different in

meaning, such as bank.


21/42

2.Transferred )( :

A word which is initially made for one

meaning but is transferred to another one and

is no longer used in its first meaning without

any context. Such as Salat' which originally

means supplication.


22/42

3. Metaphor ():

A word or phrase that ordinarily designates

one thing is used to designate another, thus

making an implicit comparison, as in a sea of

troubles.


23/42

Four Types of Comparisons

There are always four types of comparisons

between two universal words or phrases:

1. Equality ):(

that means on any example one of them

applies, the other one also applies. Such as:

triangle' and three sided polygon '.


24/42

2. Contrast ):(

That means no example of any group matches

the other group. Such as human and stone.

3. Absolute Inclusive:

That only one of them applies to the other

one. Such as New South Wales ' and Australia.


25/42

Relative Inclusive: That each one of them

partially applies to the other one. Such as

human being and black.


26/42

Homonyms : are two words that sound alikeand can even be spelled the same but meandifferent things such as: to & two & too, or

witch & which. Equivocal: open to two or more

interpretation; ambiguous; having more thanone meaning: such as bank and spring.Equivocal can be classified as a branch ofhomonym. It is not necessarily a word


27/42

it can be an ambiguous phrase.

The translators have assumed that the

Arabic term Moshakkak' has a literal meaning

and hence by mistake translated it to

equivocal'.

Univocal means having only meaning.


28/42

Conditions of Definition

1. It should not be more general than the defined.

2. It should not be less general than the defined.

3. It should not be contradictory to the defined.4. It should be more known than the defined.

5. The more general terms should be mentioned

before the less general ones.

6. It must be free from all figurative or ambiguous

words.


29/42

Argument or Reasoning is the most

complicated and perfected mental function.

Unlike a bare observation, it is a gradual

mental process and requires mental analysis.


30/42

Types of Arguments

Induction ()

The process of deriving general principles

from particular facts or instances. e.g. All crows

are black.


31/42

Analogy () : A mode of inference in which we

reason from the resemblance of two things in some

respects to their resemblance in some more

respects.

Syllogism or Deduction (): inference by

reasoning from the general to the specific.


32/42

Sophistry' or Fallacy' ( - )

If the purpose of the argument is to mislead

the audience by pretending to establish a

conclusion without really doing so, it is called

Sophistry' or Fallacy' ( - ) .


33/42

The material used for fallacy is Similarities'.There are two types of fallacies:

a) the fallacy in diction():i.e. the one arising from the misuse of language.

B) the fallacy in meaning:

i.e. the one arising from the misuse of thepremises. There are many types of fallacies.

The following are some examples:


34/42

the Fallacy in Diction

1/ the fallacy of ambiguous middle )

(

2/ the fallacy of amphiboly ( )

3/ the fallacy of accent, by stressing the wrong

part of a sentence ()


35/42

the fallacyin meaning

1/ The fallacy ofnon-sequitur( ):

i.e. the one in which there is no logical

connection whatsoever between the premises

and the conclusion. For example to prove that a

man is an adulterer by arguing that he is a showy

dresser and has often been about at nights.


36/42

2/ The fallacy of affirmation of the consequent:

The fallacy of affirming of the consequent:

e.g. If he takes arsenic he will die. He had died.

Therefore, He must have taken arsenic!


37/42

3/ The fallacy of irrelevance:

It arises when by reasoning, which though

valid in itself, one establishes a conclusion

other than that required.


38/42

4/ The fallacy of many questions:

A deceptive form of interrogation in which

a single answer usually in the form of Yes' or

No' is demanded to what is really not a single

question.


39/42

5/ The fallacy ofArgumentum ad antiquitatem :

The fallacy of asserting something is right simply

because it's old.

6/ The fallacy of argument from ignorance:

That something must be true, simply because it

hasn't been proven false, or vise versa.


40/42

7/ The fallacy of Appeal to Pity:

e.g. I didn't kill my father. I'm suffering enough

through being an orphan.

8/ The fallacy ofArgumentum ad Populum:

Millions of people in India are Hindus, so

Hinduism must be true.


41/42

9/ The fallacy of Appealing to the People:

Burn him and help your gods [21:68]

10/ The fallacy of Bifurcation:

also referred to as the black and white'

fallacy. This occurs if someone presents a

situation as having only two alternatives,


42/42

where in fact other alternatives exist or can

exist.

Documents

Logic Basic Presentation