being logical 3

8/4/2019 Being Logical 3

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BEING LOGICAL:BEING LOGICAL:

The Language of LogicThe Language of LogicPart IPart I



A statement is an expression in language that you

can say is either “true” or “false.”“Value” statements are subjective opinion and should

not be treated as objective fact. (Both in other's

arguments and your own).

A categorical statement tells us that something is

definitely the case. They communicate certain

knowledge (even if they are sometimes false).

statementsstatements



1. The Principle of Identity

2. The Principle of the Excluded Middle

3. The Principle of sufficient Reason

4. The Principle of Contradiction

Called “first” principles because they are self-evident.

They cannot be proven. Otherwise they wouldn't be

first.

The Fir The Fir st Principles of st Principles of

LogicLogic



Efficient Cause – “an agent whose activity bringssomething into existence or modifies its existence.”

-something that causes or changes something else

Final Cause – the purpose of the activity

Material Cause – material out of which an object is

composed

Formal Cause – the “identifying nature” of a thing-How you describe it

Example: a garden

Not everything has all four causes

Types of CausesTypes of Causes



All cats are mammals.- A universal statement → uses “every,” “all,” or “no”

Most cats have claws.

-A particular statement → uses “some,” “most,” onlyrefers to part of a group

GeneralizingGeneralizing



Deductive Arguments – go from general to particular

-All cats are mammals. Hello Kitty is a cat. Therefore,

Hello Kitty is a mammal.

Inductive Arguments – go from particular to general

-Hello Kitty has pointed ears. A lot of other cats havepointed ears. Therefore, it is likely that all cats have

pointed ears.

Inductive arguments are not as certain as deductivearguments

They are guided by hypotheses

-Then we gather evidence and find patterns

Inductive ArgumentInductive Argument



Arguments are composed of statements

Premise → starting point, support

-Indicators: because, since, on account of, etc.

Conclusion → true because of premise(s)

-Indicators: therefore, thus, so, etc.

Note: A single conclusion is always best

Example: Because it is raining outside, I have an

umbrella.

Founding an ArgumentFounding an Argument



Statements relate one idea to another, they are

basically comparisons

If the comparison in a statement reflects a real

relationship in objective reality then it is a true

statement

If we don't connect ideas through making

comparisons, they aren't very useful

Number and significance are both important

Analogies and comparisons

Historical event example

CompariComparisonssons



Don't assume your audience understands your

meaning -When in doubt, spell it out! :-)

Know your audience

Don't treat value statements as if they were fact

-If you want a value statement to be accepted,

you must argue it.

Avoid vague and ambiguous language

-The more general a word is, the more vague it is-When terms are very meaningful, they can be vague

-Two people can use the same word and mean

different things

Clear CommunicationClear Communication



Define your terms!

-step one: What group does the word belong to?-step two: Identify its difference from that group

Be careful with negative statements

No cats are dogs vs. all cats are not dogs-”not all” or “not every” does not equal “none”

Some cats are black vs. some cats are not black

-These say the same thing, but the affirmative isbetter

In a logical argument, it is better to avoid negative

statements

Clear CommunicationClear Communication



Are the premises true?

-How good is the evidence?

-Are there rival causes?

-Are the statistics deceptive?

-What significant information is omitted?

Are they relevant?

-Are there any fallacies in the reasoning?

Is the argument logically true?-Does it have logical structure?

Is it ontologically true?

-Does it reflect reality?

AAssessing Argumentsssessing Arguments

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