V Validity, Logical Barry Forer University of British Columbia, Vancouver, BC, Canada Synonyms Deductive logic; Inductive logic Definition Logical validity refers to the evaluation of the soundness of an argument (i.e., how well it preserves the truth) (Michalos, 2006). Description An argument consists of a series of statements that include both premises and a conclusion. The premises are the supporting evidence in the argu- ment, and the conclusion is the intended logical consequence flowing from the truth of the premises. Arguments are classified into two mutually exclusive categories: deductive and inductive. An argument is deductive when the premises provide irrefutable evidence for the conclusion (i.e., the conclusion must be true, if the premises are true). Deductive arguments are evaluated using propositional calculus, in the form of accepted rules of inference. In contrast, an argument is inductive when the premises provide supportive, but inconclusive, evidence for the conclusion. Inductive arguments are eval- uated in terms of the likelihood that the conclu- sion is true, given the premises. Another commonly claimed distinction between deductive and inductive arguments is that in the former, general premises are used to imply a conclusion about a particular instance (see Example 1), while in the latter, premises about particular instances are given as evidence for a general conclusion (see Example 2). These are indeed typical examples or deduction and induction, respectively. However, it is not neces- sarily so, for example, both the premises and conclusion in a deductive argument may be particular, and both premises and conclusion may be general in an inductive argument (Copi & Cohen, 2008). Example 1 (Deductive Argument) Premise 1: All flavors of Haagen-Dazs ice cream are delicious. Premise 2: Haagen-Dazs makes Sticky Toffee Pudding ice cream. Conclusion: Haagen-Dazs Sticky Toffee Pudding ice cream is delicious. Example 2 (Inductive Argument) Premise 1: Haagen-Dazs Sticky Toffee Pudding ice cream is delicious. Premise 2: Haagen-Dazs Vanilla Swiss Almond ice cream is delicious. A.C. Michalos (ed.), Encyclopedia of Quality of Life and Well-Being Research, DOI 10.1007/978-94-007-0753-5, # Springer Science+Business Media Dordrecht 2014