Introduction to Philosophy
What is Philosophy? (Part 2)
By David Kelsey
• The second major task of philosophy is making arguments.
• A philosopher makes arguments in performing his conceptual analysis.
– An argument about the correct definition of KNOWLEDGE or LOVE
• An argument: one statement is inferred from one or more other statements.
• Inference: a statement that follows from one or more other statements.
– The inference made:
– ‘Infer’ can also be used as a verb:
– Infer the noun:
Propositions are the meanings of sentences
• An inference: a statement that follows from one or more other statements.
• A statement is a proposition.
• A proposition: the meaning of a sentence
• Words have meanings:
• Just as words have meanings, sentences have meanings.
– Example: The cat is on the Mat.
• The form of a proposition:
– ‘it is the case that…’.
– Propositions are true or false.
Propositions & Sentences
• A sentence does two different things: it both expresses a proposition and asserts a
• The expressed proposition:
– The literal meaning of the words of that sentence.
– What is literal meaning?
– Example in Sarcasm
Expressing a proposition
• For a sentence to express a proposition:
– is for that sentence to toss the proposition up in the air, so to speak.
– It is to put the proposition up for usage.
• Knowing what proposition a sentence expresses is often quite easy.
– It is the case that…
– Example: I went to the store
The asserted Proposition
• Making use of a proposition:
– Just how a sentence makes use of the proposition it expresses determines it’s actual
or intended meaning.
• The actual or intended meaning of a sentence: what the speaker or writer of
the sentence means when she writes or says it.
– Miscommunication and the hearer’s understanding of the asserted proposition…
Asserting a proposition #2
– The actual or intended meaning of a sentence is what is asserted by the words of the sentence.
– For a sentence to assert a proposition is simply for the sentence to declare of the proposition that it is
– Example: the cat is on the mat and the cat is orange.
• Other kinds of sentences:
– The messy roomate:
• “She always takes out the trash”.
• This sentence expresses:
• But the sentence asserts:
The laws of logic
• The laws of logic: are rules for making a correct inference P given a certain set
of propositions Q1-n.
– Socrates example
• Arguments: when one proposition is inferred from one or more other
– Other definitions of an Argument
• Argument: a position supported by reasons for its truth.
– To take a position:
• taking a side or stand on an issue.
– An issue: what is raised when one considers whether or not a proposition is true.
• There are always 2 sides to an issue
– we might go as far as to say that an issue just is a question.
– Intelligent life:
– Safety belt law:
– Mac vs. Pc:
Arguments & Positions
• Arguments & Positions: so when we take a position on an issue and support it
with reasons we have given an argument.
– Intelligent life:
– Safety Belt law:
– Mac vs. Pc:
– The conclusion of an argument:
– The premises of an argument:
• Socrates again
• Raining and Pouring
What an argument isn’t
• What an argument isn’t: Let us be a bit clearer about what an
argument is by stating what it isn’t.
– Not a Fight:
– Not Persuasion:
• Advertisement example:
• Persuasion vs. Argument:
– An argument offers support for some claim, its conclusion.
– Persuasion needn’t offer any support for a point.
• Not Logic: It merely attempts to get you to believe a point.
– This attempt needn’t be one through logic though.
• Persuasion through rhetoric:
• Rhetoric: is “a broad category of linguistic techniques people use when
their primary objective is to influence beliefs and attitudes and
• Arguments vs. Explanations:
– Explanation of X: If one gives an explanation about some thing X, one gives some
details about X with the hope of coming to better understand X.
• Example: fixing a flat tire
• Conclusion Indicators: find the conclusion of an argument by looking
for conclusion indicators.
– Examples of Conclusion Indicators: therefore, hence, and others
• Premise Indicators: find the premises of an argument by looking for
– Examples of Premise Indicators: because, since, and others.
An introduction to
formalizing an argument
• Challenging an argument:
– In challenging an argument you must first formalize it.
• Formalizing an argument:
– Is the reconstruction of that argument in its most simplified form.
• Read the passage
• Write down the argument’s propositions
• Explicit premises:
– asserted by the words of the text.
• Simplifying the premises:
• Implicit or unstated premises:
– Not made explicit by the text so must be inferred from the words of the text
– Are entailed by the words of the text.
– Bloodhound example:
• Moore’s dog is a bloodhound, so it has a keen sense of smell
• What is the implicit premise?