Abstract

In this paper, the author reflects on why students so frequently have the false intuition that statements like (i) “If someone is a criminal then he comes from a single parent family,” imply their converse, namely (ii) “If someone comes from a single parent family then he is a criminal.” The author argues that this intuition is not baseless. In everyday speech, conditional statements very often refer to finite populations, meaning that while (i) does not imply (ii), (i) stands in an evidential relationship to (ii). That is, given a finite population, (i) implies that if someone comes from a single family home, it is more probable that he is a criminal. While teaching first order logic, however, conditional statements are treated as referring to infinite samples, which renders the evidential relationship insignificant. The author concludes by addressing why these differing interpretations of conditional statements should be taken into account when teaching logic.