Western University Philosophy 1230b All Key Terms

what is critical thinking

Critical thinking is the ability to think clearly and rationally about what to do or what to believe. It includes the ability to engage in reflective and independent thinking.

Someone with critical thinking skills is able to do the following:

understand the logical connections between ideas

identify, construct and evaluate arguments

detect inconsistencies and common mistakes in reasoning

solve problems systematically

identify the relevance and importance of ideas

reflect on the justification of one's own beliefs and values

The California Critical Thinking Disposition Inventory:

1. Truth-seeking

2. Open-mindedness

3. Analyticity

4. Systematicity

5. Confidence in Reasoning

6. Inquisitiveness

7. Maturity of Judgment

metacognition

is about knowing more about our own thinking processes and being able to monitor and control them. Critical thinking must involve some amount of metacognition because we need to become aware of our own reasoning and find ways to improve them.

If the premises are false...

the argument is not sound

If the premise is true and the conclusion is true...

the argument is sound

If the premise is true and the conclusion is false...

the argument is not sound

three main sentence types in English

Declarative sentences are used for assertions, e.g. "He is here."

Interrogative sentences are used to ask questions, e.g. "Is he here?"

Imperative sentences are used for making requests or issuing commands, e.g. "Come here!"

arguments

An argument is a set of statements, one of which (the conclusion) is supposed to be supported by the others (the premises).

Arguments are composed of statements.

statements

Statements are sentences or parts of sentences that assert that something is the case.

E.g. "Spot is a good dog."

AKA declarative sentences

identifying arguments

Premise indicators are expressions that indicate a premise.

Conclusion indicators are expressions that indicate a conclusion.

premise indicators

Expressions such as the following sometimes suggest that a premise follows:

because, since, for, after all,

first, second, etc.,

firstly, secondly, etc.

on the assumption that, assuming that

in view of the fact that • this follows from

this is shown/indicated/suggested/supported by

this can/may be inferred/deduced/derived from

Note that words that sometimes function as premise indicators can occur in the absence of a premise.

conclusion indicators

Expressions such as the following sometimes suggest that a conclusion follows:

therefore, so, thus, hence, consequently, in consequence

it follows that

this suggests/proves/demonstrates/entails/implies/shows that

as a result

Note that these expressions can be used in ways that don't indicate a conclusion

standard form

In order to understand, analyze, and evaluate an argument, it can be helpful to display it in a way that makes clear precisely what are the premises and what is the conclusion

This way of displaying arguments is known as the standard form (or standard format)

how to put an argument into standard form

Number and display each premise on a separate line.

Display the conclusion on the last line.

Remove all premise indicators.

Remove all conclusion indicators or replace with a simple conclusion indicator like "therefore".

Rewrite premises and conclusion so that they are complete, explicit, and clear.

validity

An argument is valid if and only if there is no logically possible situation where all the premises are true and the conclusion is false at the same time

When an argument is valid...

the truth of the premises guarantees the truth of the conclusion.

soundness

An argument is sound when it is valid and all its premises are true.

modus ponens

If P then Q. P. Therefore, Q

affirming the consequent

If P then Q. Q. Therefore, P

modus tollens

If P then Q. Not-Q. Therefore, not-P.

denying the antecedent

If P then Q, not-P. Therefore, not-Q.

hypothetical syllogism

If P then Q, If Q then R. Therefore, if P then R

disjunctive syllogism

P or Q. Not-P. Therefore, Q. ; P or Q. Not-Q. Therefore, P.

dilemma

P or Q. If P then R. If Q then S. Therefore, R or S

dilemma: When R is the same as S, we have a simpler form...

P or Q. If P then R. If Q then R. Therefore, R

arguing by reductio ad absurdum

1. First assume that S is true.

2. From the assumption that it is true, prove that it would lead to a contradiction or some other claim that is false or absurd.

3. Conclude that S must be false.

circularity

The first puzzling feature is that all circular arguments are actually valid. Here, we might take a circular argument as an argument where the conclusion also appears as a premise. Here are two examples:

God exists.

Therefore, God exists.

The moon is made of cheese.

The sun is made of tofu.

Therefore, the moon is made of cheese.

necessarily true conclusions

A more counterintuitive consequence of our definition of validity is that any argument with a necessarily true conclusion is valid, and it does not matter what the premises are and whether they are true or false

necessarily false premises

A related feature about the definition of validity is that any argument with inconsistent premises will be valid, regardless of the conclusion

valid arguments

Valid arguments are useful because they guarantee true conclusions as long as the premises are true.

generalization

A generalization, or a general statement, is a statement that talks about the properties of a certain class of objects

One way to show that an argument is invalid or unsound...

Use an invalidating counterexample!

circular arguments

A circular argument is an argument where the conclusion is also a premise.

why circular arguments are valid

In order for an argument to be invalid, there has to be a way for the premises to be true while the conclusion is false.

In other words, in order for an argument to be invalid, there has to be an invalidating counterexample.

In a circular argument, the conclusion is also a premise.

So, it's not possible for the premises to be true while the conclusion is false

tatologies

A necessarily true statement is also called a tautology.

Why arguments with necessarily true conclusions are valid...

An argument is valid if and only if there is no logically possible situation where all the premises are true and the conclusion is false at the same time.

In the case of an argument with a necessarily true conclusion, there is no possible way for the conclusion to be false.

So, there is no possible way for the premises to be true and the conclusion false

inconsistent premises

A set of statements is inconsistent when the statements cannot all be true at the same time.

Ex. If horses are mammals, then they are warmblooded. Horses are mammals. Horses are not warm-blooded

Why arguments with inconsistent premises are valid...

An argument is valid if and only if there is no logically possible situation where all the premises are true and the conclusion is false at the same time.

In order for an argument to be invalid, there has to be an invalidating counterexample--i.e., a logically possible situation in which the premises are true and the conclusion false.

the moral

The notion of validity has a precise definition.

When considering whether an argument is valid, consult that definition.

necessary conditions

To say that X is a necessary condition for Y is to say that it is impossible to have Y without X

Ex.

Having four sides is necessary for being a square.

Being brave is a necessary condition for being a good soldier.

Not being divisible by four is essential for being a prime number

sufficient conditions

To say that X is a sufficient condition for Y is to say that the presence of X guarantees the presence of Y.

Ex.

Being a square is sufficient for having four sides.

Being divisible by 4 is sufficient for being an even number.

Any two conditions X and Y are related in one of these four ways...

X is necessary but not sufficient for Y.

X is sufficient but not necessary for Y

X is both necessary and sufficient for Y.

X is neither necessary nor sufficient for Y.

types of possibilities for conditions

The concepts of necessary and sufficient conditions relate to the concept of possibility.

To say that X is necessary for Y is to say that it is not possible for Y to occur without X.

To say that X is sufficient for Y is to say that it is not possible for X to occur without Y.

There are, however, different senses of "possibility", and corresponding to these different meanings there are different kinds of necessary and sufficient conditions.

Using necessary and sufficient conditions to resolve disputes...

The concepts of necessary and sufficient conditions are quite simple, but they are very useful and fundamental concepts.

Sometimes when people disagree with each other, especially about some theoretical issue, we can use these concepts to identify more clearly the differences between the parties.

Counterexamples to claims about necessary conditions...

A counterexample to the claim that X is a necessary condition for Y is a case in which Y obtains but not X.

logical possibility

A state of affairs is logically possible just in case it is not contradictory.

A state of affairs is logically impossible just in case it is not logically possible (i.e., it is contradictory)

Example: Traveling faster than the speed of light is logically possible, since it does not contradict the laws of logic

nomological possibility

A state of affairs is nomologically possible just in case it does not contradict the laws of nature.

The laws of nature include the true laws discovered by physics, biology, and other sciences.

A state of affairs is nomologically impossible just in case it is not nomologically possible.

Something is logically possible just in case...

it doesn't contradict the laws of logic

Something is nomologically possible just in case...

it doesn't contradict the laws of nature

inductively strong arguments

an invalid argument whose conclusion is very likely to be true given that its premises are true

inductive strengh

has to do with how much the premises support the conclusion, and not with the actual truth or falsity of the premises and the conclusion.

deductive arguments

an argument that is intended to be valid

deductive arguments example

If Freddie is a fish, then Freddie can't fly. Freddie is a fish. It follows for sure that Freddie can't fly.

Why is inductive strength defeasible while validity is not?

In an inductively strong argument, the conclusion is true in most but not all logically possible situations in which the premises are true.

Adding premises might inform us that we are likely to be in a situation in which the original premises are true but the conclusion is not true.

In a valid argument, the conclusion is true in all logically possible situations in which the premises are true.

Adding new premises might inform us with respect to which of these situations actually obtains, but it cannot inform us that we are in a situation where the conclusion does not obtain

Intuitively, a good argument must...

1. Have true premises

2. be valid or inductively strong

3. not beg the question

4. have plausible premises

5. have relevant premises

argument mapping

An (simple) argument is a set of one or more premise with a conclusion.

A complex argument is a set of arguments with either overlapping premises or conclusions (or both).

Complex arguments are very common because many issues and debates are complicated and involve extended reasoning.

what is an argument map

a diagram that captures the logical structure of a simple or complex argument.

Co-premises vs independent premises

Argument maps allow us to depict the difference between two ways in which premises can support a conclusion:

1. The premises work together (co-premises)

2. The premises work independently (independent premises)

cro-premises

Two or more premises are co-premises when they work together to support a conclusion.

independent premises

Two or more premises are independent premises when they work independently to support a conclusion.

multi-layered arguments

A multi-layered argument is an argument in which some premises are supposed to be supported by other premises.

Multi-layered arguments have "multiple layers" of argumentation.

Premises that are supposed to be supported by other premises are intermediate conclusions in a multilayered argument.

The conclusion of a multi-layered argument is the main conclusion.

sub-arguments

Multi-layered arguments are made of several overlapping sub-arguments.

A multi-layered argument has as many sub-arguments as it has conclusions and intermediate conclusions combined.

One strategy for multi-layered argument mapping:

Identify the conclusion (i.e., the main conclusion).

Identify the main argument.

Identify any sub-arguments.

importance of language

Critical thinking involves assessing claims and how they relate to one another.

Claims are often expressed in language.

literal meaning

The literal meaning of a word is the meaning assigned to it by convention.

E.g., "bachelor" means unmarried man.

E.g., "Aria couldn't be luckier" means it is impossible for Aria to be luckier.

literal meaning vs what is conveyed

Sometimes a statement conveys, hints at, suggests, implies, or implicates more than what it literally means.

conversational implicature

One important way in which a statement can convey more than its literal meaning is through conversational implicature.

Conversational implicatures are implicatures that arise from a particular conversational context.

cancelling conversational implicatures

Conversational implicatures can be cancelled.

In contrast, literal meaning cannot be cancelled.

bachelor = unmarried man

The definiendum → the term being defined

The definiens → the words that define the definiendum

two main kinds of definitions

Reportive definition

Stipulative definition

reportive definition

A reportive definition is a definition that reports a term's existing meaning.

AKA "lexical definition"

These are the definitions dictionaries aim to provide.

E.g. Bachelor = unmarried man

Triangle = a closed figure with three sides

stipulative definition

A stipulative definition is a definition that assigns a meaning to a term.

E.g. Nostud = something that there is no need to study

Harm case = a moral dilemma that involves a choice between two harmful outcomes

Stipulated definitions are also used to introduce new technical terms like "prion", "quark", "supervenience".

two ways reportive definitions can be incorrect

1. They can be too broad (too wide):

The definiens applies to things that the definiendum (the defined term) does not apply to.

E.g. Airplane = a flying machine

Too wide because helicopters are flying machines but not airplanes

2. They can be too narrow:

The definiens fails to apply to things that the definiendum (the defined term) does apply to.

E.g. Religion = a belief system that includes a belief in a supernatural being that created the universe

Too narrow because there are religions that don't include a belief in a supernatural being, such as Jainism and some versions of Buddhism and Daoism

Ways any definition can be inadequate

Circularity

Obscurity

circularity - 2nd term

It can be circular in that the definiens cannot be understood without a prior understanding of the defined term.

E.g. Red = the colour red things have

obscurity

It can be obscure in that its definiens do not provide a clear understanding of the defined term.

E.g. Science = searching for a black cat in a dark room

precising definition

A precising definition is a definition that attempts to precisify the meaning of a term.

It is a kind of stipulative definition that aims to respect existing usage to some degree.

persuasive definition

A persuasive definition is a definition that attaches an emotive, positive, or derogatory connotation to a term when the term does not have such a connotation.

Some terms do have such a connotation, so it is appropriate for a reportive definition to include it (e.g., weed) - such a definition would not be a persuasive definition.

verbal dispute

A verbal dispute is an apparent disagreement in which the parties agree on the relevant facts but use words differently.

A factual dispute is a disagreement in which the parties disagree on a fact.

ambiguity

Ambiguous expressions are expressions that mean or refer to more than one thing

types of ambiguity

Lexical ambiguity

Referential ambiguity

Syntactic ambiguity

lexical ambiguity

A word or expression exhibits lexical ambiguity when it has more than one one literal meaning.

Examples: "bank"

referential ambiguity

A case of referential ambiguity is one in which it is not clear what is being referred to.

These are often cases in which there are multiple interpretations for what a pronoun (like "she", "he", "him" or "they") or a quantifier (like "everything" "somebody" or "most") is referring to

syntatic ambiguity

A case of syntactic ambiguity is a case in which an expression can be understood as having multiple grammatical structures with different meanings.

disambiguation

To disambiguate an ambiguous expression, we specify the various interpretations

equivocation

An argument equivocates when a key term in it switches meaning

Example: Philosophy is deep. - It's possible to drown in deep things. - Therefore, it's possible to drown in philosophy.

This argument equivocates on the word "deep".

linguistic pitfalls types

Ambiguity

Vagueness

Incomplete meaning

Inappropriate emotional connotation

Category mistake

Empty meaning

Jargon and gobbledygook

linguistic pitfall

inappropriate uses of language that hinder accurate and effective communication.

This can happen when we use language that is unclear, distorted, or empty in meaning.

vagueness

A term (or statement) is vague just in case it is indeterminate exactly which things it applies to (or when it is true).

E.g: "Tall" and "Sam is tall."

incomplete meaning

Some terms have incomplete meanings in that their use presupposes certain standards of comparison.

E.g. "similar," "useful"

If it's not clear what the intended standards are, their meanings are unclear.

Example: True or false: "Starbucks coffee is better and delivered faster."

problem with incomplete meaning

When using or encountering terms with incomplete meanings, make sure the relevant standards are obvious or clearly specified.

If the relevant standards are not clear, the meaning of an expression is unclear.

category mistakes

A category mistake occurs when a statement ascribes a property to something that it does not make sense for an object of that kind to have.

Example: Information wants to be free.

- The fact that it's cloudy outside argues that it might rain today

Category mistakes can effectively convey truths.

empty meaning

A statement has an empty meaning when it provides little or no information.

The statement might express a logically necessary truth.

jargon

Groups of people (e.g., doctors, philosophers, carpenters, WoW players) use specialized vocabulary (jargon) to communicate quickly and effectively.

Using jargon is fine when one's audience knows what the jargon means.

But when jargon is used to communicate with an audience that doesn't know what it means, it impedes effective communication

Jargon can be inappropriately used to be evasive or convey authority, intelligence, sophistication, or that one belongs to a certain group, or to intimidate one's audience.

Gobbledygook:

Gobbledygook is obscure and convoluted language, e.g., language that is full of jargon, wordy, or convoluted.

Sometimes people use gobbedygook to sound smart and convey authority.

scientific methodology

Science is an activity that consists in the explanation, prediction, and control of empirical phenomena in a rational manner.

By "scientific reasoning" we mean the principles of reasoning relevant to the pursuit of this activity.

four main concepts in scientific eresearch

1. Theories - These are the hypotheses, laws and facts about the empirical world.

2. The world - All the different objects, processes and properties of the universe.

3. Explanations and predictions - We use our theories to explain what is going on in the world, and to make predictions. A crucial part of scientific research is to test a theory by checking whether its predictions are correct or not.

4. Data (evidence) - The information that is gathered from observations or experiments. We use data to test our theories.

To understand a scientific theory, we need to be able to say:

1. which are the laws, principles and facts included in the theory,

2. what do these theories tell us about the nature of the world,

3. what can it predict and what can it explain

4. what are the main pieces of evidence used to support the theory, and whether there might be evidence against the theory.

the hypothetical-deductive method (hd)

Identify the hypothesis to be tested.

Generate predications from the hypothesis.

Use experiments to check whether predictions are correct.

If the predictions are correct, then the hypothesis is confirmed. If not, then the hypothesis is disconfirmed.