82 PART II. SOME IMPORTANT METHODOLOGICAL TERMS. 



relations, presence or absence of particular substances, etc.J 

 and in devising such experiments the utmost precautions are 

 required to secure a decisive result free from all complications 

 and entirely unequivocal. A scientific experiment of a high 

 order may be defined as consisting of observation or registration 

 of a methodical character by means of carefully constructed 

 apparatus under deliberately selected and varied conditions.- 

 Experiment, for instance, of a non-instrumental character, 

 but not less rigorous, is urgently needed in certain departments 

 of natural history. Books without number have been published 

 concerning the mentality of animals, and yet certainty in this 

 matter completely escapes us. What is required is systemati- 

 cally to observe dogs, cats, fowl, and other domesticated animals, 

 common birds, etc., preferably one male and one unrelated 

 female together (in order to include activities connected with 

 the perpetuation of the species and the rearing of offspring) 

 from birth to a natural death, in an environment where no 

 other members of the same or closely related species exist in 

 the vicinity, and to chronicle faithfully and intelligently the 

 behaviour of the individuals thus isolated. It seems almost 



1 For a list of the general characteristics of phenomena, see the Table of 

 Primary Categories in Conclusion 3. 



2 "Experience may be acquired in two ways: either, first, by noticing facts 

 as they occur, without any attempt to influence the frequency of their 

 occurrence, or to vary the circumstances under which they occur; this is 

 Observation; or, secondly, by putting in action causes and agents over which 

 we have control, and purposely varying their combinations, and noticing 

 what effects take place; this is Experiment." (Sir John Herschel, Discourse, 

 [67.].) "Passive and active observation might better express their distinction." 

 (Ibid.) 



"Observation is finding a fact, experiment is making one " (Bain, Logic, 

 vol. 2, p. 43.) 



"When we merely note and record the phenomena which occur around 

 us in the ordinary course of nature we are said to observe. When we 

 change the course of nature, by the intervention of our muscular ppwers, 

 and thus produce unusual combinations and conditions of phenomena, we 

 are said to experiment. . . . Experiment is thus observation plus alteration 

 of conditions." (Jevons, Principles of Science, p. 400.) "One of the most 

 requisite precautions in experimentation is to vary only one circumstance 

 at a time, and to maintain all other circumstances rigidly unchanged." 

 (Ibid., p. 422.) "One of the great objects of experiment is to enable us to 

 judge of the behaviour of substances under conditions widely different from 

 those which prevail upon the surface of the earth." (Ibid., p. 426.) 



"Experiment is the practical means by which we furnish ourselves with 

 observations in such number, and involving such mutual differences and 

 affinities, as is requisite in order to the elimination of what is unessential 

 in them and the derivation from them of a pure case." (Lotze, Logic, vol. 2, 

 pp. 39-40.) 



" Scientific experiment, therefore, is scientific observation performed under 

 accurately known artificial conditions." (Huxley, Introductory, 1900, p. 17.) 



"Experiment is observation under artificial conditions." (Bosanquet, Logic, 

 vol. 1, p. 143.) "Experiment would usually be considered to begin where 

 we pass from intentional selection of our standpoint, and from the use of 

 contrivances auxiliary to perception, to actual analytic interference with the 

 object under observation." (Ibid., p. 143.) 



