JXXLT 10, 1908] 



SCIENCE 



55 



the psycliology upon wliich sociology rests, 

 and which furnishes society with both its 

 motor power and its guidance. That is an 

 entirely different and far more important 

 science. Social psychology is the science of 

 the mutual influence of psychic phenomena. 

 Mr. H. G. Wells has properly described it as 

 " an exhaustive study of the reaction of people 

 upon each other and of all possible relation- 



Social psychology, thus understood, has 

 been treated by all kinds of writers. Very 

 little of value has been contributed by the 

 psychologists proper. When they approach it 

 they load it with such a mass of technical 

 terms, borrowed from their psychological 

 "jargon" — dialectic, ego, alter, socius, eject, 

 project, subject, etc., with the innmnerable 

 derivatives of these terms, that, however com- 

 monplace such ideas may be, the reader's 

 mental stomach is so turned by their pedantic 

 iteration that it is incapable of following 

 what little thought they may represent. 



But many writers besides Tarde have treated 

 special aspects of the subject with clearness 

 and force. Among these Dr. Eoss himseK 

 must be counted and placed in the front rank, 

 for his " Social Control " and other writings 

 deal primarily with social psychology. In the 

 present work he lays under contribution a 

 great array of authors and a vast literature. 

 No attempt can be made here to summarize 

 this body of knowledge. The arrangement of 

 the material is the original part of the work, 

 and this could not probably be improved upon. 



In some of the later chapters Dr. Eoss has 

 been able to free himseK more fully from his 

 historical bearings, and to strike out into 

 fields more distinctly his own. This is espe- 

 cially the case with Chapter XV., on the Eela- 

 tion of Custom Imitation to Conventionality 

 Imitation, and Chapter XVI., on Eational 

 Imitation, which is the coming form of imita- 

 tion based on intelligence and scientific knowl- 

 edge. Chapter XVIII., on the role of Dis- 

 cussion, is also luminous, and pushes the sub- 

 ject some distance beyond the point where 

 Bagehot left it. Chapter XXI., on Com- 



^"A Modem Utopia," New York, 1907, p. 83. 



promise, is all too brief, and John Morley is 

 not mentioned. 



The fiual chapter (XXIII.), on Disequili- 

 bration, deals with invention (in the Tardean 

 sense), and displays an astonishing grasp of 

 the progress of human thought. No one has 

 better shown how it is that premature dis- 

 coveries lie dormant till the world is ready 

 for them. Under the heading that " the 

 higher the degree of possibility, the sooner the 

 invention is likely to be made," he says (pp. 

 359-360) : 



The inventions (or discoveries) in a particular 

 iield — and often those in diflferent fields — are in a 

 chain of dependence which obliges them to occur in 

 a series. Each ushers in a train of possibles. Now 

 when no intervening invention needs to be made, 

 an invention may be said to be in the first degree 

 of possibility. When it is contingent on another 

 yet to be made, it is in the second degree of possi- 

 bility. And so on. Now, when an invention or 

 discovery reaches the first degree of possibility, 

 it is ripe. Thus, after Kepler announces the laws 

 of planetary movement, the discovery of the 

 principle of xmiversal gravitation is in order at 

 any moment. After Galileo has proclaimed the 

 laws of the pendulum, its use in time-keeping 

 needs but a single stride. The electric telegraph 

 is due any time after Ampere's discoveries. The 

 invention of Crookes's tubes brings the X-ray into 

 the foreground of possibility. After the discovery 

 of the Hertzian waves, a few short steps bring 

 wireless telegraphy upon the scene. 



And in showing " how society can promote 

 invention," he significantly adds (p. 360) : 



The difficulty of making the combination of 

 ideas for any particular invention will depend 

 upon the number of persons who possess these 

 ideas, and on the frequency in this number of 

 individuals with the intellectual capacity neces- 

 sary to combine the ideas into the invention. 

 There is no way of affecting the latter condition, 

 for the genius is in no wise a social product; but 

 organized society can affect the former condition. 

 A universal system of gratuitous instruction with 

 special aid and opportimities for those who show 

 unusual power amounts to an actualizing of all 

 the potential genius in a population, and is the 

 only rational policy for insuring a continuous 

 and copious flow of inventions. It is hardly neces- 

 sary to point out that only a stimulating, equip- 

 ping education can mature geniuses. A r^me 

 that prunes, clips and trains minds levels genius 



