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)