THE PSYCHOLOGY OF DECEPTION. 157 



many types of deception described, but that they are too compli- 

 cated and varied to be capable of rigid analysis : the moment de- 

 ception becomes conscious, there must be acting and subterfuge to 

 maintain the appearance of sincerity. If we add this great class 

 of deceptions to those already enumerated, we may perhaps realize 

 how vast is its domain, and what a long, what a sad chapter would 

 be necessary to contain the history of human error. 



Ethics is so closely related to psychology — right knowing to 

 right doing — that a brief " hcpcfdbula docet " by way of summary 

 may not be out of place. We find, first, a class of sense-decep- 

 tions which are due to the nature of sense-organs, and deceive 

 only so long as their true nature remains imknown. These are 

 neither pernicious nor difficult to correct. Next come a class of 

 deceptions that deceive because we are ignorant of the possibili- 

 ties of conjuring and pronounce upon the possibility or impossi- 

 bility of a certain explanation in advance of complete knowledge ; 

 of this I have already said enough. But most dangerous and 

 insidious are the deceptions in which self-deception plays the lead- 

 ing role. The only safeguard here is a preventive : the thorough 

 infusion of sound habits of thought, a full recognition of the con- 

 ditions under which the testimony of consciousness becomes 

 doubtful, an appreciation of the true value of objective scientific 

 evidence, and an inoculation against the evils of contagion by an 

 independent, unprejudiced logical schooling. When once these 

 evils of self-deception, fed by the fire of contagion and emotional 

 excitement have spread, reason has little control. As Prof. 

 Tyndall tells us, such " victims like to believe, and they do not like 

 to be undeceived. Science is perfectly powerless in the presence 

 of this frame of mind .... It [science] keeps down the weed of 

 superstition, not by logic, but by slowly rendering the mental soil 

 unfit for cultivation." With the spread of education, with the 

 growth of the capacity to profit by the experiences of others, 

 with the recognition of the technical requisites that alone qualify 

 one for a judgment in such matters, with a knowledge of the pos- 

 sibilities of deception and of the psychological processes by 

 which error is propagated, the soil upon which spiritualism and 

 kindred delusions can flourish will be rendered unfit. 



Thk French Academy of Sciences recently had a discussion about the " Canals" 

 of Mars. A paper by M. Fizeau remarked upon the resemblance between some 

 drawings of these objects and M. Nordenskiold's view of the great Icelandic glacial 

 crevasse in Greenland as indicating that the whole surface of Mars is covered, down 

 to the equator, with a glacial ice-cap. M. Janssen thought that they were rather 

 crackings resulting from the advanced planetary age of Mars, with excessive cool- 

 ing and absorption of the oceans and atmosphere, or crevasses in the rocky crust 

 corresponding with the furrows of the moon. 



