Glossary of Critical Thinking Terms 

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Argument:  A kind of rationale in which the reason(s)  are intended to be taken as evidence for believing the conclusion..
   
Branch:  One of multiple chains in a rationale that lead to the same conclusion.

Cause:  A reason in an explanation.  

Chain:  A sequence of reasons connected by principles which lead directly from the terminal reason to the conclusion..

Deduction:  A form of reasoning in which the premises given are intended to be taken as deductively implying  the conclusion.

Deductive Implication:  A logical relation between  premises and conclusion in which it is impossible for the premises to be true and the conclusion false.  

Deductive Validity:   Synonymous with deductive implication.  A rationale that deductively implies its conclusion is said to be deductively valid.

Evidence:  A reason in an argument.  Evidence provides a basis for believing a conclusion to be true.

Explanation:  A kind of  rationale in which the reason(s) are intended to be taken as the cause(s) of the fact represented by the conclusion.

Fact:  The actual state of affairs represented by a true statement.  (E.g.,  "Bill is a cat", if true, represents the fact that Bill is a cat.)

Fallacy:  A systematic mistake in reasoning. (See index of fallacies)

Induction:  A form of reasoning in which the premises are intended to inductively imply the conclusion.

Inductive Implication:  A logical relation between premises and conclusion in which it is very unlikely for the premises to be true and the conclusion false.

Inductive Strength:  A measure of the degree to which a rationale inductively implies its conclusion.  

Inductive Validity:  Synonymous with inductively valid and inductively strong.  A rationale that inductively implies its conclusion is said to be inductively strong or inductively valid.

Instance:  A reason that is a relatively concrete example of its conclusion.  Instances are not connected by principles.

Issue:  The fundamental question addressed by a particular rationale.  In an argument the issue is always whether (or not)  the conclusion is true. In an explanation the issue is always why or how the fact represented by the conclusion came to be.

Opinion:  The belief that a certain statement is true.

Practical Implication:  A logical relation in which a reason, either explanatory or argumentative in nature, implies  its conclusion, and no known exceptions to the principle apply to the case at hand.

Premise:  Any statement made in support of a conclusion.

Principle:  A generalized conditional statement that provides the rational connection between  a reason and a conclusion. 

Rationale:  The logical structure composed of reason(s) supporting a conclusion.  There are two types of rationale:  argument and explanation.

Reason: A statement given in practical support of a conclusion.  There are two types of reason:  cause and evidence.

Reasoning:  The process of constructing or analyzing rationales.

Terminal Reason:  The final reason in a chain of reasoning.
 
Statement:  A sentence that is intended to be taken as either true or false.

Subject:  The basic situation or events that reasoning is concerned with.  The subject is not a statement, and it is not synonymous with the issue.