PHI 120 Study Guide - Final Guide: Categorical Proposition, Obversion, Fallacy
30 May 2018
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PHI 120 – Final Study Guide | R.Jones 1
Chapter 1
Vocabulary:
Logic: The study of reasons and inferences. The systematic, organized evaluation of arguments.
Arguments: A group of statements made up of premises and one conclusion.
Statements: Sentences with truth values.
Truth Value: Whether a particular statement is true or false.
Premise: Statements that provide supporting evidence.
Conclusions: Statements of the claim supported by the premises.
Premise Indicator: A word or phrase that lets the reader/hearer know that the statement is a
premise. (i.e. – Since, because, for, as indicated by, seeing that, as, given that, owing to, etc.)
Conclusion Indicator: A word or phrase that lets the reader/hearer know that the statement is
the conclusion. (i.e. – Therefore, so, thus, consequently, hence, for this reason, as a result, etc.)
Inferential Relationship: When a group of statements is presented as a chain of reasoning.
Explicit Claim: The conclusion in a argument that contains premise/conclusion indicators.
Implicit Claim: The conclusion in an argument that doesn’t contain indicators.
Conditional Statement: Statements with the structure “If A, then B.”
Sufficient Condition: Having X means you automatically, definitely have Y.
Necessary Condition: When you absolutely cannot have B unless you have A.
Deductive Argument: An argument in which the conclusion necessarily follows from the
premises. If the premises are true, it is impossible for the conclusion to be false.
Inductive Argument: An argument in which the conclusion is made likely by the premises. If
the premises are true, the conclusion is probably true.
Valid: A deductive argument is valid when it is impossible for the conclusion to be false if the
premises are true.
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PHI 120 – Final Study Guide | R.Jones 2
Invald: A deductive argument is invalid when it is possible for the conclusion to be false even if
the premises are true.
Sound: Valid plus all the premises are true.
Unsound: Invalid, or valid but one or more premise is false.
Strong: An inductive argument is strong when it is very likely that the conclusion is true if the
premises are true.
Weak: An inductive argument is weak when it unlikely that the conclusion is true if the premises
are true.
Cogent: Strong plus all the premises are true.
Uncogent: Weak, or strong but one or more premise is false.
Necessary or Sufficient?
SUFFICIENT –
If you have one thing, you either have or are something else in a larger category. If you’re a
Collie, you’re automatically placed in the larger category that is dogs.
i.e. Being a Collie is a sufficient condition of being a dog.
NECESSARY –
When you definitely CAN’T be something if you are not another thing. You can’t be a dog if
you are not an animal.
i.e. Being an animal is a necessary condition for being a dog.
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PHI 120 – Final Study Guide | R.Jones 3
Finding the Conclusion of an Argument
To find a conclusion, look for either an implicit or explicit claim. Meaning, look for indicators. A
conclusion will be the final statement combining the premise(s). If an explicit claim, the
conclusion will have an indicator word or phrase.
What isn’t an Argument?
- Chains of statements offering advice or warning
- Chains of statements expressing beliefs or opinions
- Chains of statements reporting facts
- Expository Passages
- Illustrations
- Conditional Statements
Does the passage prove a point?
Inductive or Deductive?
Look for objective features of an argument:
- Occurrence of special indicator words
- Actual strength between premises and conclusions
- Form/style of argument
Valid or Invalid? (Deductive)
Can only determine validity from truth values if the premises are true and the conclusion is false.
True premise and false conclusion is invalid.
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Document Summary
Arguments: a group of statements made up of premises and one conclusion. Truth value: whether a particular statement is true or false. Conclusions: statements of the claim supported by the premises. Premise indicator: a word or phrase that lets the reader/hearer know that the statement is a premise. (i. e. since, because, for, as indicated by, seeing that, as, given that, owing to, etc. ) Conclusion indicator: a word or phrase that lets the reader/hearer know that the statement is the conclusion. (i. e. therefore, so, thus, consequently, hence, for this reason, as a result, etc. ) Inferential relationship: when a group of statements is presented as a chain of reasoning. Explicit claim: the conclusion in a argument that contains premise/conclusion indicators. Implicit claim: the conclusion in an argument that doesn"t contain indicators. Conditional statement: statements with the structure if a, then b. Sufficient condition: having x means you automatically, definitely have y.
