Abstract

This paper points out a recent error that has been occurring in logic and critical thinking textbooks concerning the definition of a deductively valid argument. Namely, a number of authors define a deductively valid argument as one where the conclusion must be true if the premises are true. This definition is mistaken as it attaches necessity to a statement (the conclusion) rather than to the relationship between premises and the conclusion. In addition to detailing this mistake in a number of textbooks, the paper provides three correct definitions of a valid argument.