5i8 SCIENCE PROGRESS 



forms of matter and radiation. This theory he adopts as 

 making unnecessary the conception of aether. The dualism 

 still remains, however ; if it is no longer matter and energy, it 

 is positive and negative electricity. Ihe antithesis is to some 

 extent reduced, but it is still there ; nor is speculation likely to 

 cease until some hypothesis of aether is framed which renders 

 monism intelligible, or until it is shown that monism can never 

 be reached, but that dualism is a fundamental fact, not capable 

 of further analysis. 



Prof. James Gibson has published a very complete study of 

 Locke's Theory of Knowledge. He makes a microscopical 

 examination of the Essay Concerning Human Understanding, 

 aiming at exposition and a true interpretation, rather than 

 criticism. The main value of the book is therefore historical 

 rather than philosophical. An elaborate study is carried out 

 of the relations of Locke to Scholasticism, to Descartes, Hobbes, 

 Leibnitz, and Kant. The line of thought culminating in Hume 

 is omitted from this examination, which nevertheless is an 

 important contribution to the history of philosophy. 



Prof. J. S. Mackenzie has aimed at a more ambitious project 

 in his Elements oj Constructive Philosophy. This is a survey of 

 the whole field of philosophy, in which however most attention 

 is devoted to ethical conceptions and to the subject of infinity. 

 Prof. Mackenzie's preoccupation with ethics somewhat militates 

 against the scientific interest of the book. Science seeks what 

 is true ; ethics seeks what is right ; a mixture of these two 

 aims does not conduce to lucidity of thought. Thus, we fail to 

 see what result is gained by an argument in favour of " The 

 right to hope." Prof. Mackenzie urges that where the solution 

 of a certain problem cannot be proved, we still have " the 

 right to hope " that it is true, and we have also the right to 

 entertain so much belief as is necessary to support the hope. 

 That in plainer words is saying that, if we desire a thing to be 

 true, we are ipso facto justified in attaching a certain amount of 

 credence to it. We are far removed here from the scientific 

 spirit, where belief is determined by exclusive reference to 

 objective facts, to the complete suppression^ personal predilec- 

 tions. The instance given is the proposition that the Universe 

 can only be made intelligible " by thinking of it as constructed 

 in accordance with the idea of perfection." But perfection is 

 a mere idea of the human mind : the aesthetic sentiments 



