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Philosophy 103 Linguistics 103 Yet, still, Even further More Introductory Logic: Critical Thinking. Dr. Robert Barnard. You earned it! . New Policy: All phones and digital/cellular communication devices must be off. ON PAIN OF POP QUIZ. …tell your pals – no more warnings…. Last Time : .

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Philosophy 103 linguistics 103 yet still even further more introductory logic critical thinking l.jpg

Philosophy 103Linguistics 103Yet, still, Even further MoreIntroductory Logic: Critical Thinking

Dr. Robert Barnard


You earned it l.jpg
You earned it!

New Policy:

All phones and digital/cellular communication

devices must be off. ON PAIN OF POP QUIZ.

…tell your pals – no more warnings…


Last time l.jpg
Last Time:

  • Laws of Thought: Philosophical Issues about the status of logical laws.

  • Meaning

    • Types of Meaning: Cognitive/Emotive

    • Intension vs. Extension

    • Ambiguity and Precision

    • Names vs. Descriptions


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Plan for Today

  • Talk about Definitions

  • Time Permitting: Return to the issue of logical form…


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Definitions:

  • Parts of a Definition

    • Definiendum: The word or term or concept to be defined

    • Definiens: the word or group of words which are used to define (assign a meaning to) another term or concept


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Types of Definitions

Lexical

Precising

Theoretical

Persuasive


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Lexical Definition

A Lexical Definition reports or describes how a term is actually used in a language.

Sometimes a term has more than one definition.-


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The ‘Idea’ of a definition

i·de·a       (ī-dē'ə)   n.   Something, such as a thought or conception, that potentially or actually exists in the mind as a product of mental activity.

  • An opinion, conviction, or principle: has some strange political ideas.

  • A plan, scheme, or method.

  • The gist of a specific situation; significance: The idea is to finish the project under budget.

  • A notion; a fancy.

  • Music A theme or motif.

  • Philosophy

    • In the philosophy of Plato, an archetype of which a corresponding being in phenomenal reality is an imperfect replica.

    • In the philosophy of Kant, a concept of reason that is transcendent but nonempirical.

    • In the philosophy of Hegel, absolute truth; the complete and ultimate product of reason.

  • Obsolete A mental image of something remembered.

There are at least 3 specific philosophical definitions!!!


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Precising Definition

A Precising Definition is designed to reduce the vagueness of a term in use. This is a kind of stipulative definition.

Example: Tom is rich.

(What does ‘rich’ mean?)

…we might extend the lexical definition by adding that here ‘rich’ means “has more than 5 million dollars.” This makes the term PRECISE in our context.


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Theoretical Definition

A THEORETICAL DEFINITION assigns (stipulates) a meaning to a term by suggesting a theory that gives a certain characterization of the entities the theory denotes.

Theoretical definitions are common in mathematics and science. They fix the meaning of a term for a specific use.


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Examples: Theoretical Definitions

Geometry: “Parallelstraight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction. ” (Euclid Elements I, Def 23)

Chemistry: “An electron is a stable fundamental atomic particle with almost no mass and a negative charge.”


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Pursuasive Definition

A Persuasive Definition is a definition designed to produce a favorable or unfavorable emotional attitude toward whatever is denoted by the definiendum.

Persuasive definition relies upon both cognitive and emotive meaning. Since they exceed the scope of cognitive meaning, persuasive definitions are primarily rhetorical.


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Persuasive Definition Examples

Neutral Definition:

Abortion: In medicine, an abortion is the premature exit of the products of conception (the fetus, fetal membranes, and placenta) from the uterus. It is the loss of a pregnancy and does not refer to why that pregnancy was lost.


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Unfavorable Emotive attitude definition:

Abortion: The willfulmurder of innocent unborn children, often performed to avoid the personal and societal consequences of wantonsexual activity.

Favorable Emotive attitude definition:

Abortion: The constitutionally protected act of medically resolvinga pregnancy for the purpose of restoring, preserving or protecting the physical or mental health of a woman. The procedure is especially useful in protecting women from potentially debilitating consequences of rape and incest.


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Some Tools for Developing Definitions…

  • Point to a case of the Definiendum (ostention)

  • Specify the INTENSION of the term.

  • Enumerate (in part or whole) the EXTENSION of the term.

  • Make the term precise by tracing its place in a taxonomy.


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Ostensive (pointing) Definition

By “Dog” I mean: 

By “Flux Capacitor” I mean: 


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Definition by Intension

Here we indicate the characteristics or qualities that the definiendum connotes.

Square: regular figure on a Euclidian plane bounded by four sides of equal length and four right angles.

Fish: cold-blooded, aquatic vertebrates, with gills, commonly fins, and often an elongated body covered with scales.


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Definition by Enumeration (extension)

Even numbers: 2, 4, 6, 8, 10, 12, 14, 16 …

Blue: the common feature of blueberries, the sky on a clear day, some people’s eyes, the ocean in some places, …


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Taxonomic Definition by Genus and Differentia

This sort of definition relies upon the fact that our concepts are often related by being more or less general. We have broad terms for general types and then other words for specific sub-types or case sunder the general heading.

The GENUS is the general type

The DIFFERENTIA is the characteristic that marks a specific sub-class or case.

A Genus and Differentia together define a SPECIES.



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Definitions and Meanings

  • Some terms have meaning which we record or report with a lexical definition.

  • Some terms have more than one meaning, we use precising definition to stipulate which meaning is relevant.

  • Some terms are given meaning by a definition (ostensive, enumerative, theoretical)

  • Some definitions contain emotive content that can be confused with cognitive content.




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Good vs. Bad Arguments

  • DeductiveValidity – IF the premises are true THEN the conclusion MUST be true.

  • InductiveStrength – IF the premises are true THEN the conclusion WILL BE PROBABLE.

  • DeductiveSoundness – the deductive argument is valid AND premises are all true

  • InductiveCogency—The inductive argument is strong and the premises are all true


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Deduction and Argument Form

  • In order to talk about validity we need to come back to the idea of an argument form.

  • Form is the STRUCTURE of the argument.

  • The Structure can either be good or bad. It can either do its job or not.

  • A good structure will allow the premises to support the conclusion.


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Review: Standard Form of an Argument

  • Sample Argument:

    Socrates is mortal because all men are mortal

  • Standard form isolates conclusion and lists ALL premises.

  • All men are mortal (given premise)

  • Socrates is a man (implied premise)

  • Socrates is mortal. (Conclusion)


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Logical Form of an Argument

  • Determining Logical FORM:

If Al likes Sally then Al will ask Sally out

Al likes Sally

Therefore Al will ask Sally out

If -- P -- then -- Q--

-- P –

Therefore -- Q --

We Determine FORM by isolating the logical structure of the argument.


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Another example of logical form

[R] Every school teaches religion and religious beliefs. This can be seen by the fact that either a school is religious or not. And if it isn’t it either teaches a form of secular humanism or teaches atheism by teaching nothing. Both humanism and atheism therefore teach specific beliefs about religion.


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Isolate Conclusion FIRST

Every school teaches religion and religious beliefs. This can be seen by the fact that either a school is religious or not. And if it isn’t openly religious then it either teaches a form of secular humanism or teaches atheism by teaching nothing. Both humanism and atheism therefore teach specific beliefs about religion.


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LIST PREMISES

This can be seen by the fact that either a school is religious or not.

And if it isn’t openly religious then it either teaches a form of secular humanism or teaches atheism by teaching nothing.

Both humanism and atheism therefore teach specific beliefs about religion.

Every school teaches religion and religious beliefs.


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CLARIFY PREMISES

1. Every school is openly Religious or not-openly Religious.

2. If a school is not openly religious then it either teaches secular humanism or teaches atheism by teaching nothing.

3. Both humanism and atheism are specific beliefs about religion.

SO…

4. Every school teaches religion and religious beliefs.


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Add in an obvious assumed premise…

  • Every school is openly Religious or not-openly Religious.

  • All openly Religious schools teach religion and religious beliefs

    3. Both humanism and atheism are specific beliefs about religion. (re-ordered).

    4. If a school is not openly religious then it either teaches secular humanism or teaches atheism by teaching nothing.

    SO…

    5. Every school teaches religion and religious beliefs.


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SUBSTITUTE FOR TERMS

  • If S(chool) then R(eligious) or not-R.

  • If R, then T(eaches religion)

  • If not-R then H (teach humanism) or A (teaches atheism) (old 4 moved up)

    4. If H then T and If A then T

    SO…

    5. Every S is T


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Clarify

  • If S then (R or not-R).

  • If R, then T

  • If not-R then (H or A)

  • (If H then T) and (If A then T)

    SO…

    5. If S then T (re-stated ‘if x then y’ = ‘all x are y’


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Issues !!!

  • Is the form valid?

  • Is the analysis here correct? (Is Religious belief the same as belief about religion?)

  • Are the premises true (soundness?)


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Validity and Form

KEY POINT:

VALIDITY is a property of FORM

  • If a given argument is valid, then ANY argument with the SAME FORM must also be VALID.

  • Likewise: if a given argument is not valid, then ANY argument with the SAME FORM must also be INVALID.


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REMEMBER!!!!

  • Check on Homework

  • Remember that the first QUIZ is due this week

  • Quiz PW is “fallacy”

  • Quiz is 1 take only!

  • Quiz is open between T and R only!

  • You have 200 minutes to complete 75 items.


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