ment; that it does no more than this is due to the simple fact that the personal bias is as varied as humanity itself, and that the deflecting impulses in any given case are to be referred to a complex of factors almost eluding analysis. To follow this part of the subject into detail would, therefore, manifestly be impossible. But certain of the larger and more widely influential of these disturbing forces may be roughly marked out by way of illustration.
In the first place, there is what we may call the professional bias. Exclusive devotion to separate lines of activity, study, or thought inevitably gives the mind a particular set or twist. Bacon complains that Aristotle, primarily a logician, made his natural philosophy the slave of his logic. Few specialists can escape the insulation consequent upon living too continuously in a confined area of problems and ideas. Their intellectual outlook is necessarily circumscribed, facts are seen by them out of proper perspective, and one-sidedness of training and discipline renders their judgment of things partial and incomplete. The lawyer carries his legal, the theologian his theological, the scientist his scientific bent of mind into every inquiry; with what grotesque results is only too frequently apparent. Accustomed to move in a single narrow groove, and wholly absorbed in the contemplation of certain isolated classes of phenomena, they unconsciously allow their particular interests to dominate their thought, and impose disastrous restrictions upon their view of whatever lies outside their own chosen field.
Secondly, we have the bias of nation, rank, party, sect. Here the mental disturbances are too numerous to permit and too obvious to require special exemplification. Intellectual provincialism of any kind is fatal to large and fertile thought, alike by limiting the range of our knowledge and sympathies and by inducing mental habits and implanting prejudices which prevent us from seeing things in wide relations and under a clear light. So long as our point of view is simply that of our country, our class, our party, or our church, so long, it is evident, our minds will lack the breadth and flexibility necessary for free inquiry, fruitful comparisons, sane and balanced judgments.[1]
Finally, among the Idols of the Cave "which have most effect in disturbing the clearness of the understanding," mention must be made of the temperamental bias. Every man, it has been said, is born Platonist or Aristotelian; it is certain that the great divisions in thought—religious, philosophical, political—answer roughly to fundamental differences in human nature, and that every one not checked or turned aside by extraneous influences will spontaneously gravitate in one or another direction. Bacon is only re-
- ↑ Cf. Spencer's Introduction to the Study of Sociology, chapters viii-xii.
