The aims of this paper are to illustrate where previous attempts at the characterisation of slippery slope arguments have gone wrong, to provide an analysis which better captures their true nature, and to show the importance of achieving a clear definition which distinguishes this argument structure from other forms with which it may be confused. The first part describes the arguments of Douglas Walton and others, which are found wanting due to their failure to capture the essence of the slippery (...) slope and their inability to distinguish SSAs from other consequentialist forms of argument. The second part of the paper puts forward a clear analysis of what is special about SSAs: it is argued that all SSAs, properly so-named, claim that reaching a certain conclusion, A, involves the negation of a thitherto accepted principle, P, and that that principle is necessary to argue against further conclusions which are considered unacceptable. (shrink)

Experimental research suggests that people draw a moral distinction between bad outcomes brought about as a means versus a side effect (or byproduct). Such findings have informed multiple psychological and philosophical debates about moral cognition, including its computational structure, its sensitivity to the famous Doctrine of Double Effect, its reliability, and its status as a universal and innate mental module akin to universal grammar. But some studies have failed to replicate the means/byproduct effect especially in the absence of other factors, (...) such as personal contact. So we aimed to determine how robust the means/byproduct effect is by conducting a meta-analysis of both published and unpublished studies (k = 101; 24,058 participants). We found that while there is an overall small difference between moral judgments of means and byproducts (standardized mean difference = 0.87, 95% CI 0.67 – 1.06; standardized mean change = 0.57, 95% CI 0.44 – 0.69; log odds ratio = 1.59, 95% CI 1.15 – 2.02), the mean effect size is primarily moderated by whether the outcome is brought about by personal contact, which typically involves the use of personal force. (shrink)