Throughout this book, deduction has been examined and discussed from many angles and perspectives. However, one question has remained conspicuously unaddressed until now: Is deduction a correct, reliable method for reasoning? In other words, is deduction justified (Dummett, 1978)?

This investigation has focused extensively on the social conditions and factors influencing the emergence of deduction, both historically and ontogenetically. It is thus reasonable to ask whether it offers a social constructivist account of deduction, which in turn has implications for the justification problem. Indeed, on at least some versions of social constructivism, the very question of the correctness of deductive reasoning as a scientific method, understood in absolute terms, is seen as misguided.