Smith, M. Erkenn (2013) 78: 1069. doi:10.1007/s10670-012-9376-5
In ‘Single premise deduction and risk’ (2008) Maria Lasonen-Aarnio argues that there is a kind of epistemically threatening risk that can accumulate over the course of drawing single premise deductive inferences. As a result, we have a new reason for denying that knowledge is closed under single premise deduction—one that mirrors a familiar reason for denying that knowledge is closed under multiple premise deduction. This sentiment has more recently been echoed by others (see Schechter 2011). In this paper, I will argue that, although there is a kind of risk that can accumulate over the course of drawing single premise deductive inferences, it is importantly different to the kind of risk that multiple premise deductive inferences can introduce. Having distinguished these two kinds of risk, I shall offer some reasons for thinking that the kind associated with single premise deductions is, in fact, epistemically benign—it poses no threat, in and of itself, to the knowledge status of a belief. If this is right, then Lasonen-Aarnio’s argument against single premise closure is unsuccessful.