Inferences are made when a person (or machine) goes beyond available evidence to form a conclusion. With a deductive inference, this conclusion always follows the stated premises. In other words, if the premises are true, then the conclusion is valid. Studies of human efficiency in deductive inference involves conditional reasoning problems which follow the "if A, then B" format.
The task of making deductions consists of three stages. First, a person must understand the meaning of the premises. Next they must be able to formulate a valid conclusion. Thirdly, a person should evaluate their conclusion to tests its validity. Although deductive inference is easy to test or model, the results of this type of inference never increase the semantic information above what is already stated in the premises.
Blackwell's Dictionary of Cognitive Science
Johnson-Laird, Philip N., Human and Machine Thinking, 1993.
Contributed by Valerie Trifts