Hypothetical Propositions

HYPOTHETICAL PROPOSITIONS

Carina Lauren M. Lumacad, RN

HYPOTHETICAL PROPOSITION

Does not declare an unconditional affirmation or denial

Expresses a relation of dependence such as an opposition or a likeness between two clauses.

Kinds of Hypothetical Propositions

1. Conditional Proposition2. Disjunctive Proposition3. Conjunctive

Proposition

1. CONDITIONAL PROPOSITION

Expresses a condition or relation of dependence between two propositions

The expressed relation points out that one proposition necessarily follows from the other

Conditional Proposition

Examples:1. If animals can think, they are

rational.2. If the barometer falls, there will

be a storm.*** two parts are joined by if,

unless, when, where, suppose, in case

Conditional Proposition

“if-then” propositionsUsual structure: If A is B, then C is

D

Example:If dry weather continues, the harvest will be poor.

Two Component Propositions of a

Conditional Proposition1. Antecedent (Implicans)2. Consequent (Implicate)

Antecedent (Implicans)

Introduced by the word if or its equivalent.

Contains the condition.

Consequent (Implicate)

Expresses the statement that follows the acceptance of the condition i.e. the statement that depends upon the presence of the condition

The one that is conditioned.

Antecedent & Consequent

The antecedent precedes the consequent

Example:If a man is farsighted, he needs

eyeglasses. (Antecedent) (Consequent)

Antecedent & Consequent

A conditional proposition enunciates the dependence of the consequent upon the antecedent.

Dependence

The dependence is always logical i.e. we pass from the antecedent to the consequent in our thought or speech.

The dependence is real i.e. when the consequent depends on the antecedent in reality.

Dependence

Logical dependence: “If the ground is wet, it must have rained.”

Real dependence:“If it have rained, the ground would have been wet.”

2. DISJUNCTIVE PROPOSITION

One whose subject or predicate consists of parts which exclude each other.

“either-or” statementParts of a disjunction are called

disjuncts (alternants)

Disjunctive Proposition

Examples:1. A body is either in motion or at

rest.2. Man is the result of either of

creation or of evolution.3. Either the sun or the earth

moves in an orbit.

Proper Disjunction(perfect, complete,

strict) If and when the parts (disjuncts)

are mutually exclusive. Disjuncts can neither be true nor

false together at the same time.Examples:1. An individual is either honest or

dishonest.2. It is either raining or not raining.

Improper Disjunction (imperfect, incomplete)

One whose parts are not mutually exclusive.

One disjunct does not necessarily exclude the other.

Example:1. Jose is either sitting or writing.

Broad Disjunction

If and when at least one disjunct is true, but the other disjunct may also be true.

Example:1. Either my sister or I will go.

Strict or Broad Disjunction?Consider the content and context

within which occurs.A true, perfect, complete, strict &

proper disjunctive requires: 1. the enumeration of the possibilities must be complete. 2. there must be an exclusive

opposition between or among the enumerated possibilities.

3. CONJUNCTIVE PROPOSITION

One which denies that two contrary predicates together can be true of the same subject at the same time.

Denies the simultaneous possibility of two alternatives.

Conjunctive Proposition

Examples:1. You cannot stand and sit at the

same time.2. You cannot be in Quiapo and in

Makati at the same time.

Conjunctive Proposition

The truth of a conjunctive proposition depends solely upon a true exclusive opposition existing between their common parts.

The parts of a conjunctive are called conjuncts.

Conjunctive Proposition

Reducible to two connective hypothetical propositions or a combination of hypothetical and categorical propositions.

Reducing Conjunctive Proposition

Example:1.You cannot be in Quiapo and in Makati at the same time.

1.a. If you are in Quiapo, then you are not in Makati.

1.b. If you are in Makati, then you are not in Quiapo.

References

1. Celestine N. Bittle, The Science of Correct Thinking. Revised ed. (Milwaukee:The Bruce Publishing Co., 1950), 119-123.

2. Florentino T. Timbreza, Logic Made Simple for Filipinos. (Quezon City:Phoenix Publishing House inc., 1992), 50-53.