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TESTIMONY AND AUTHORITY. 79 In results arrived at by reasoning on the facts of observa- tion and experiment we are, however, not under the neces- sity of relying wholly upon others. The reasoning admits of being dissected and critically examined. It is not, like an experiment or observation, an event limited to some par- ticular place and time ; but is capable of repetition merely at the expense of intellectual exertion. Yet, even after the analysis has been carried to its farthest limit, there will still remain the facts of observation or experiment on which it is based. And as to these we may still be under the compul- sion of relying upon the assertions of others. Our conclusion is then that necessity for reliance on others exists nowhere except as to certain matters of observation or experiment ; and as to these only in so far as they them- selves are unanalysable or simple facts. The critical con- clus^ons of competent investigators may on certain occasions be adopted on practical grounds without a sifting of the evidence ; but to repeat a former remark this can receive no justification from the point of view of abstract logic. An assertion being given us, if it can be analysed it should be. If it cannot we must either suspend judgment or see how far the assertor satisfies the conditions of trustworthiness. If we are unable to do this, we finally have no choice but to avoid coming to a conclusion until we can. Among the various kinds of authorities the Specialist and Expert deserve more particular mention. The terms are perhaps not very sharply distinguished ; but ' specialist ' adverts rather to the attainment of high proficiency by a limitation in the range of inquiry ; while the term ' expert ' imports the possession of a high degree of skill or capacity. They seem to differ also in this, that while the specialist must possess all the qualities of authority the expert need not. The latter may be an expert in some one or more of the particular kinds of skill or capacity that go to the making of authority. Thus we may have experts in observation, or in experiment, or in some particular variety of one of these. The two terms, however, are often used synonymously. The natural home of the Expert seems to be the Law Courts, where especially in Patent litigation his habit is to distribute his favour impartially between plaintiffs and defendants. This habit of his gives point to the question : What is the proper way to use him ? How can he best be made to give reliable assistance IB any inquiry? We have already seen that the argument from authority is logically defensible only when no other sufficient evidence