The Continuum Fallacy in Moral Philosophy

ABSTRACT ‘Spectrum arguments’ or ‘continuum arguments’ in moral philosophy are sometimes invalid because they commit a particular fallacy I call the ‘Continuum Fallacy’. An important example is an argument in population ethics described by Derek Parfit, which purports to derive a conclusion that he and others find repugnant on the basis of a weak and plausible premise. Parfit treats this as a paradox, and takes up the challenge of resolving it, looking for a way to avoid the Repugnant Conclusion. The solution he offers depends on the existence of imprecision within the relation of betterness among populations of people. Other philosophers have taken up the same challenge, following Parfit's lead, and offered solutions also based on imprecision or incommensurability. I show that actually the Repugnant Conclusion is not implied by Parfit's appealing premise. There is therefore no paradox and no real challenge. Moreover, the explanation of why this is so has nothing to do with imprecision, incompleteness, incommensurability, indeterminacy or vagueness in betterness. It is consistent with a sharp, complete betterness ordering.