DEVELOPMENT OF MODERN COMPARATIVE PSYCHOLOGY 



499 



[ower forms and insisted that physico- 

 lemical process and the resulting be- 

 lavior of the organism constituted the 

 roper subject matter of the science within 

 ; this field. They denied the validity of 

 inferences concerning the presence and 

 nature of mental states in lower animals, 

 agreeing in general with Loeb that the 

 ability to profit by experience should be 

 the accepted criterion of psychic life, or 

 consciousness. Moreover, they opposed 

 the use of the subjective terminology of 

 traditional human psychology in describ- 

 ing the activities of lower organisms. In 

 a joint paper issued in 1899, Beer, Bethe, 

 and von Uexktill (93) proposed to elimi- 

 nate entirely such terms as sensation, 

 sense-organ, memory, learning, etc. In- 

 stead of the terms hearing, smell, and 

 sight, they would speak of phono-recep- 

 tion, stibo-reception and photo-reception, 

 and for sense-organ they proposed the 

 term reception-organ. 



Loeb objected strenuously to the usual 

 interpretation of "preference method" 

 results in terms of sensation, choice, 

 algedonic or aesthetic factors. He insisted 

 that evidence for differential sensitivity 

 was not in itself evidence of qualitatively 

 different sensations or even of the presence 

 of sensation at all. He believed the 

 tropism theory could be broadened out to 

 cover all instinctive, and perhaps even 

 much of the socalled intelligent behavior 

 of organisms, although he accepted con- 

 sciousness as a concomitant of the higher 

 associative processes. The theory solved, 

 so he thought, the metaphysical problems 

 involved in current conceptions of con- 

 sciousness and volition. The importance 

 of Loeb, in this historical connection, 

 does not involve the question as to the 

 ultimate truth or falsity of his special 

 theory, either as at first announced or as 

 later elaborated. The physico-chemical 

 views of Verworn and Loeb provoked 



widespread discussion and were factors of 

 major importance in clearing away the 

 loose, unscientific attitude that prevailed. 

 Morgan, as well as Lubbock before 

 him, maintained the right of the investi- 

 gator to study the activities of animals 

 for their own sake, without special 

 reference to the all-absorbing controversy 

 over mental evolution, and thus helped to 

 give a systematic orientation to compara- 

 tive psychology. Morgan's Introduction 

 (176) covering the vertebrates together 

 with Lubbock's earlier volume (167) 

 limited largely to invertebrates were 

 important indicators of the general trend 

 in this direction. The canon of Morgan, 

 which was first announced in the Introduc- 

 tion (1894) deserves to rank along with the 

 tropism theory of Loeb as a signal attack 

 against the current humanizing tendency. 

 While it was distinctly less radical in 

 spirit, nevertheless it was widely opposed 

 at first, although it came in time to 

 serve as the rallying cry of the more 

 conservative group. The canon runs as 

 follows: "In no case may we interpret an 

 action as the outcome of the exercise of a 

 higher psychical faculty, if it can be 

 interpreted as the outcome of the exercise 

 of one which stands lower in the psycho- 

 logical scale." This is merely the law of 

 parsimony applied to comparative psy- 

 chology; it is an insistence that the same 

 critical attitude which had been long 

 accepted in the methodology of general 

 science be also adhered to in this field. 

 Even the conservatives could hardly reject 

 a principle so fundamental and reasonable, 

 and the influence of this canon on the 

 later development of the science has been 

 most important. For though it did not 

 rule out entirely the fallacious practice of 

 attempting to infer the subjective life of 

 the organism by anthropomorphic analogy, 

 it did serve to introduce a measure of 

 restraint into such speculation. 



