- 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.