 Obviously we must start from the facts of the use of a name, and shall be guided at first certainly by the name: and so far we may appear to be examining the meaning of a name. Next we have to think about the individual instances, to see what they have in common, what it is that has actuated us. […] At this stage we must take first what seems to us common in certain cases before us: next test what we have got by considering other instances of our own application of the name, other instances in which has been working in us. Now when thus thinking of other instances, we may see that they do not come under the formula that we have generalized. […] There is a further stage when we have, or think we have, discovered the nature of the principle which has really actuated us. We may now correct some of our applications of the name because we see that some instances do not really possess the quality which corresponds to what we now understand the principle to be. This explains how it should be possible to criticize the facts out of which we have been drawing our data. (SI, 44–45)