 Rational scepticism, as a motive for rejecting a scheme that offers to remove admitted evils, involves two applications of probability. The first is…that social affairs are so complex that it is very improbable that all the effects of a given social change have been foreseen. But…we must have some ground for judging further that the unforeseen effects are more likely to be bad than good…this judgment cannot rest on the known nature of the effects of this particular measure [but only] on some general proposition, such as: It is more probable that the unforeseen effects of any social change will be bad than that they will be good. [There is] no reason to think [this]. (Broad 1913: 397)