NOORMA FITRIANA M. ZAIN

RIANA WIEKE ADININGTYAS

LOGICUNIT 12

DEFINITION

Logic deals with meanings in a language system, not with

actual behavior of any sort. Logic deals with

PROPOSITIONS. The terms “logic” and “logical” do not

apply directly to UTTERANCES (which are instances of

behavior)

Jhon acted quite logically in locking his door.

Means: Jhon had good, well thought-out reasons for doing

what he did.

LOGIC is a word that means many things to different people.

Many everyday uses of the worg logic and logical could be

replaced by expressions such as reasonable behavior and

reasonable.

Logic is just one contributing factor in rational behavior.

Rational behavior involves:

a) Goals

b) Assumptions and knowledge

c) Calculating

Example of rational behavior:

Goal : to alleviate my hunger

Assumption and knowledge:

Hunger is alleviated by eating food.

Cheese is food.

There is a piece of cheese in front of me.

I am able to eat piece of cheese.

Calculations:

If hunger is alleviated by eating food and cheese is

food, then hunger is alleviated by eating cheese.

If hunger is alleviated by eating cheese, then my own

hunger would be alleviated by eating this piece of

cheese in front of me, and

Eating this piece of cheese would alleviate my hunger,

And my goal is to alleviate my hunger,

So therefore eating this piece of cheese would achieve

my goal.

(Rational) action: eating the cheese

There is a close analogy between logic and arithmetic (which is

why we have used the word calculation).

‘arithmetic fact’ = not only fact involving number but fact arising

from system of the rules, such as: (+), (-), (x), and (: )

A similarity between logic and arithmetic is the UNTHINKABLE

of alternatives

Example: “2 + 2 = 5”

it is unthinkable.

it is arithmetic contradiction

“All men are mortal and some men are not mortal”

it is unthinkable

it is a logical contradiction

LETS PRACTICE !

Mark each sentence for Contradiction (C) or for

Analytic (A) as appropriate.

1. Sandra is here and Sandra is not here

2. Either Sandra is here or Sandra is not here

3. If Sandra is here, Sandra is here

4. If everyone is here, no one is not here

5. If someone is here, the no one here

A NOTATION FOR SIMPLE PROPOSITIONS

Logic provides a notation for unambiguously representing the

essentials of proposition.

Simple proposition likes simple sentences, have just one

predicator, which write is CAPITAL LETTERS.

Example:

Abraham died would be presented by formula a DIE.

Fido is a dog f DOG

Ted loves Alice t LOVE a

Phil introduced Mary to Jack p INTRODUCE m j

Unit 13

SIMPLE PROPOSITION

It is representable by a single PREDICATOR, drawn from the predicates in

the language, and number of ARGUMENTS, drawn from the names in the

language. This implies, among other things, that no formula for simple

proposition can have TWO (or more) predicators, and it cannot have

anything which is neither a predicate nor a name.

Example:

j LOVE m a well-formed formula for SP

j m not a well-formed formula, because it contains no predicator

j IDOLIZE ADORE m not a well-formed formula for SP, because it

contains two predicators

j and h LOVE m not well-formed formula for SP because it contains

something ‘and” which neither a predicator nor a name.

Rule: A simple formula consisting of a name and one-place predicate

is true of a situation in which the referent of the name is a

member of the extension of the predicate.

Example:

Mother is standing m STAND is true of the situation

Son is sleeping s SLEEP is false of the situation

see page 159

THANK YOU….