4. Judgements and Propositions (Handout)

8/12/2019 4. Judgements and Propositions (Handout)

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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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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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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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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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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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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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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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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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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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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.

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4. Judgements and Propositions (Handout)