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HUMN9
PART III: JUDGEMENT AND
PROPOSITION
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Judgement
After simple apprehension of things in the world, ourmind, to better understand the things we perceivemove on to the next step, which is judgement.
Judgementmental operation that pronounces the
agreement or disagreement between two ideas.e.g. simple judgements:
When the mind is able to apprehend the terms square andpolygon the mind is able to judge A square is apolygon.
On the other hand, when the mind is able to apprehend theterms boy and girl the mind is then able to judge thatA boy is not a girl.
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Elements of Judgement
The mind takes three things into consideration beforemaking a judgement call (either agreeing ordisagreeing) between two ideas Understanding of each of the ideas about which a
judgement is to be made.One has to understand first theindividual concepts of square and polygon to make ajudgement about the two ideas.
Comparison of the two ideas in questionfocused onidentifying the ideas.
e.g. A squarehas four equal sides and four right angles; a polygonisa figure that has many angles and of course many sides.
From the those definitions, we can deduce that the commondenominator between a square and a polygon is that they bothhave angles and sides. Hence their identities are established.
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The mental act pronouncing that the ideas
compared are in agreement or disagreement. This
is the ACTUALjudgement.
e.g. A square is a polygon.
Note: that simple apprehension is useless if it
does not lead to judgement
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Truth of a Judgement
Since simple apprehension of ideas come from
the perception of reality, we can say that the
truth of judgements are/MUST BE based on
reality. We may have judgements based on
perceived ideas such as, A dog is a man, but
that would be false. Therefore all judgements
must conform to reality (A dog is an animal.)
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Propositions
Propositionsare verbal or written expressionsof judgements. Much like terms are the verbalor written expressions of ideas. A proposition
has three elements namely, subject, predicate,and the copula (or the conjunction).
The subject and predicate in a logical propositionare called the matter because they are the focus
of the proposition. The conjunction, on the otherhand, combines the subject and predicate.
e.g. The grass is green
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Proposition and Sentence
You have to remember that all propositions
are sentences. But not all sentences are
propositions.
Non-propositional sentences:
Interrogative sentence: How are you?
Imperative sentence: Get out!Exclamatory sentence: Ouch!
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Propositions
Subjectis that which something is being said
about (man)
Copulaexpresses a relation of identity or
non-identity (is, is not)
Predicatethat which is affirmed or denied of
a subject term (a rational being)
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Quantity of Subjects
Classification of Terms according to Quantity:
singular, particular, and universal
The same classification according to quantity
applies to propositions
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Quantity of Subjects
Singular proposition
When the subject designates a definite individual
or group
e.g.
-The Philippines is rich in natural resources.
-Ikko Oquias is a philosophy instructor at CvSU.
-A logic student is not a dog.
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Quantity of Subjects
Particular proposition
When a subject term designates a part of a totalextension
e.g.-Some logic students do not know what particular
propositions are.
-Some agility heroes in DoTA are better equipped
with The Butterfly.
-Some logic students have no idea what I just said.
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Quantity of Subjects
Universal propositions
when the subject term designates all members of an
extension or group, or parts of a given class or whole
e.g.
-All students in logic are beautiful and handsome.
-All instructors of logic are a lot more handsome
and beautiful than the students.-Love is blind.
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Quality of Copula
-or the quality of a proposition is the relationestablished between two terms of the proposition, asshown in its copula. Can be classified in two ways:
- Affirmative: if there is an agreement between the two
terms; expressed by the copula is and are and otherlinking verbs
e.g. Listening to the lecture is the key to understanding the lesson.
- Negative: if there is disagreement between the two terms:
expressed if the copula is modified by a negation not orother negative terms
e.g. Listening to the lecture is not the only key to passing thesubject.
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Quantity of Predicates
The predicate of a categorical proposition may
be universal, singular, or particular. In
determining the quantity of a predicate of a
categorical proposition, we have to rememberthe following:
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Quantity of Predicates
Singular predicates
if the predicate designates a definite individual or
group
e.g.
The best teacher in logic is Mr. Oquias.
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Quantity of Predicates
Particular predicates if the predicate is NOTsingular, and the copula is AFFIRMATIVE
e.g.
Smoking weed is illegal.An honest life is a decent one.
Note that predicates like a decent one does not necessarily
mean that a predicate is singular since an article a is not asign of singularityin other words, one would have toanalyze the predicate in order to know if it is singular ornot.
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Quantity of Predicates
Universal predicates
if the predicate is NOT singular and the copula is
NEGATIVE
e.g.
Most Caviteos are not poor.
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Categorical Proposition
In Aristotelian logic, there are four types ofpropositions according to class Asingular/universal affirmative proposition
Esingular/universal negative proposition
Iis a particular affirmative proposition Ois a particular negative proposition
A and I are affirmative; while
E and O are negative
A and I are said to be derived from the Latin wordAffirmo (to affirm)
E and O from the Latin word Nego (to deny)
Singular subjects are also considered universal.
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APropositions
All Caviteos are Filipinos.
All teachers are human.
My mother is a woman. All dogs are cute.
People who smoke weed are happy.
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E Propositions
The logic teacher is not gay.
She is not my girlfriend.
Computers are not edible. No terrorists are pacifists.
Neither tequila nor vodka are my favorite
alcohol.
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I Propositions
Some people with dark skin are Africans.
Some logic students are drunkards.
Most violators are criminals. Several of my students are grammatically
challenged.
Almost all grammatically challenged studentsare failing English classes.
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O Propositions
Not all individuals are citizens.
Not everyone who studies are people who
pass.
Some jeepney drivers are not sweet lovers.
Some married couples are not straight.
A lot of church-goers are not going to heaven.
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Quantity of the Subject and Predicate
Asubject is always universal; predicate isparticular
Esubject is always universal; predicate is
universal Isubject is always particular; predicate is always
particular
Osubject is always particular; predicate is
always universal
Take note that all of the above are the general ruleswhile a few exemptions will be discussed later
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Hypothetical Propositions
While categorical propositions are simple
sentences, hypothetical ones are compound
sentences that indirectly states something.
Being compound it consists of a proposition which
combines at leasttwo sentences
e.g.
If I were a boy, then I think I could understand.
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Hypothetical Propositions
There are three types of hypothetical propositions, namely:
1. Conditional Proposition
Expressed using the ifthen clause, or its equivalents. It states thedependence of the then-clause (consequent) to the if-clause
(antecedent). The truthof a conditional is dependent on the formal and real
dependence of the consequent to the antecedentso no matterhow absurd a consequent is, but does follow from the antecedent, itis still true.
e.g.
If I fall in love with him, then I am blind. You havent experienced real happiness if you havent been drunk
yet.
Real pain is only felt if you have a massive hangover.
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Hypothetical Propositions
2. Disjunctive Propositions
Contains alternative parts implying that at least
one of them is true; both parts are called
disjuncts, which is introduced by either..or..clauses or equivalent words like else, unless, and
otherwise.
Is considered true if at least one of its
component parts is true
There are two types of disjunctive propositions
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Hypothetical Propositions
3. Conjunctive Proposition Connects two parts (propositions) called conjuncts
through words cannot beandat the same time. Itsimply says that things, attributes, or modes cannot betrue at the same time.
It is considered true if the parts cannot co-existsimultaneously; if one conjunct is true, the other mustbefalse; but the falsity of one does not implythe truth ofthe other conjunct.
e.g.
You cannot be drunk and sober at the same time.
You cannot be a boy and not understand at the sametime.