ABSTRACT
It is customary in science to regard certain facts as ‘data’, from which laws and also other facts are ‘inferred’. The practice of inference is much wider than the theories of any logician would justify, and it is nothing other than the law of association or of ‘learned reactions’. In the present chapter, I wish to consider what the logicians have evolved from this primitive form of inference, and what grounds we have, as rational beings, for continuing to infer. But let us first get as clear a notion as we can of what should be meant by a ‘datum’.
