logic basic presentation
TRANSCRIPT
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Logic
Basic Presentation
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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.
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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.
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Thus, logic is defined as:
: Logic is a legal instrument (organon)
utilizing which protects the mind from
incorrect thinking .
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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.
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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.
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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
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statements to establish a definite proposition
is called Argument' (al-Hojjah). The unknown
which is known through inference is called
Conclusion' (al-Natijah) .
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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).
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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.
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Francis Bacon (1561-1626) and Immanuel Kant
(1724-1804) were also the first opponents of
the Aristotelian logic in western philosophy.
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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 ) ( .
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In acquired knowledge the knower and the
known are different. The Knowledge bridges
them together. Such as our knowledge about
Mecca City.
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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.
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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:
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a) the concept of the subject,
b) the concept of its attribute,
c) the concept of the relation between them
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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
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2. Universal )( :
Universal is a word which has more than one
example such as: human being, city.
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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.
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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.
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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.
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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.
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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 '.
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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.
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Relative Inclusive: That each one of them
partially applies to the other one. Such as
human being and black.
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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
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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.
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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.
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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.
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Types of Arguments
Induction ()
The process of deriving general principles
from particular facts or instances. e.g. All crows
are black.
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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.
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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' ( - ) .
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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:
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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 ()
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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.
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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!
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3/ The fallacy of irrelevance:
It arises when by reasoning, which though
valid in itself, one establishes a conclusion
other than that required.
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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.
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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.
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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.
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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,
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where in fact other alternatives exist or can
exist.