5.6: Key Terms

Abductive

having to do with abduction/abductive reasoning. Abduction is probabilistic form of inference in which an explanation is offered to justify and explain evidence.

Ad hominin attack

fallacy of relevance that argues against someone’s idea or suggestion by attacking the individual personally, rather than pointing out problems with the idea or suggestion.

Appeal to ignorance

a fallacy of weak induction that relies on the lack of knowledge or evidence for a thing (our ignorance of it) to draw a definite conclusion about that thing.

Argument

a set of reasons offered in support of a conclusion.

Begging the question

a fallacy of unwarranted assumption that either assumes the truth of a conclusion in the course of trying to prove it or assumes the truth of a contentious claim.

Biased sample

a fallacy of weak induction that draws a conclusion using evidence that is biased in some way.

Conclusion

the result of an argument. A conclusion is that which is meant to be proved by the reasoning and premises used in an argument.

Conditional

a logical statement that expresses a necessary and a sufficient condition. Conditionals are usually formulated as if–then statements.

Contradiction

a statement that is always false. A contradiction is the conjunction of any statement and its negation.

Counterexample

an example that proves that either a statement is false or an argument is invalid.

Deductive

having to do with deduction/deductive reasoning. Deduction is a form of inference that can guarantee the truth of its conclusions, given the truth of the premises.

Emotional appeal

fallacy of relevance that appeals to feelings (whether positive or negative) rather than discussing the merits of an idea or proposal.

Explanatory virtues

aspects of an explanation that generally make it strong; four such virtues are that a good hypothesis should be explanatory, simple, and conservative, and have depth.

Fallacy

a poor form of reasoning.

Fallacy of diversion

a general category of informal fallacies in which an arguer presents evidence that functions to divert the attention of the audience from the current subject of argument.

Fallacy of relevance

a general category of informal fallacies in which an arguer relies on reasons that are not relevant for establishing a conclusion.

Fallacy of unwarranted assumption

a general category of informal fallacies in which an arguer implicitly or explicitly relies on reasons that require further justification.

Fallacy of weak induction

a general category of informal fallacies in which an arguer’s evidence or reasons are too weak to firmly establish their conclusion.

False cause

fallacy of weak induction in which a causal relation is assumed to exist between two events or things that are not causally connected; “correlation does not equal causation”.

False dichotomy

a fallacy of unwarranted assumption in which a limited number of possibilities are assumed to be the only available options.

Hasty generalization

fallacy of weak induction that draws a conclusion using too little evidence to support the conclusion.

Hypothesis

a proposed explanation for an observed process or phenomenon.

Inductive

having to do with induction/inductive reasoning. Induction is a probabilistic form of inference in which observation or experience is used to draw conclusions about the world.

Inference

a reasoning process that moves from one idea to another, resulting in conclusions.

Invalidity

a property of bad deductive inferences. An invalid inference/argument is one in which the truth of the premises does not guarantee the truth of the conclusion.

Law of noncontradiction

a logical law that states that contradictory statements/propositions can never be true in the same sense at the same time.

Law of the excluded middle

a logical law that states that for any statement, either that statement or its negation is true.

Logical analysis

the process of determining whether the logical inferences made in an argument are good. A logical analysis determines whether the premises in an argument logically support the conclusion.

Necessary condition

X is a necessary condition for Y if and only if X must be true given the truth of Y. If X is necessary for Y, then X is guaranteed by Y—without the truth of X, Y cannot be true.

Premise

evidence or a reason offered in support of a conclusion.

Red herring

fallacy of diversion that ignores the opponent’s position and simply changes the subject.

Statement

a sentence with a truth value—a sentence that must be either true or false.

Strawman

fallacy of diversion that utilizes a weaker version of the position being argued against in order to make the position easier to defeat.

Sufficient condition

X is a sufficient condition for Y if and only if the truth of X guarantees the truth of Y. If X is sufficient for Y, then the truth of X is enough to prove the truth of Y.

Truth analysis

the process of determining whether statements made in an argument are either true or false.

Universal affirmative statement

statements that take two groups of things and claim all members of the first group are also members of the second groups.

Validity

a property of deductive arguments where the structure of an argument is such that if the premises are true, then the conclusion is guaranteed to be true. A valid inference is a logically good inference.