THE BREEDING BEHAVIOUR OF THE FROG I55 



is not disposed to deny Russell's idea of directivcncss — in fact he seems 

 to think that it is obviously true, but he does not see that it can be a 

 useful help in the teclinique of investigation. In a soincwliat similar 

 way, he takes pains to explain that the behaviourist school do not 

 assert that animals have no emotions, but only that we camiot know 

 whether they have them or not, and so we cannot usefully employ the 

 concept. Bicrens de Haan has severely criticized the behavourists for 

 their statements that we can only observe such states of mind as anger 

 or hunger in ourselves. They do not believe that we can observe such 

 states even in another human, imless speech is used to convey the 

 information. I agree with Biercns de Haan in this respect, for the idea 

 seems to me not only to be contrary to common sense but to be 

 mathematically improbable. We conduct our lives on the assumption 

 that we can detect himger or anger or pleasure in other men and in 

 other animals by observation in both cases. What seems to have 

 happened is that words invented by our ancestors and appHcd to 

 man and to other animals have been captured, philosophically 

 examined, labelled "Not to be used except with reference to yourself" 

 and then returned to circulation. Tinbergen defends this restricted 

 use on the grounds that, if we say that an animal is hungry, we may 

 retard an investigation into why it is hungry by accepting the state- 

 ment as an explanation. In human affairs, however, we rarely accept 

 such statements as "B is angry" without asking why B is angry, and 

 I cannot see why we should do so when we are discussing other 

 animals. That one animal. Homo sapiens, is so different from all 

 others that only it has emotions seems to me to involve a probability 

 that cannot be measured, but must be small, when it is considered 

 that the other differences we know are mostly quantitative. The 

 neutral, agnostic attitude is, in that case, not the most logical. 



It is possible that somewhere in this controversy, the distinction 

 between the attitudes of mind needed to carry out the process of 

 inductive thought, wliich is an imaginative act, has become confused 

 with the attitude needed to carry out a deductive investigation. If the 

 directiveness of Russell or the psychology of Bierens de Haan stimu- 

 lated the production of a hypothesis to be tested according to the 

 objective methods of Tinbergen, science might be advanced rather than 

 retarded. 



In this chapter, I shall occasionally make use of words on the zoo- 

 logical "Index Expurgatorius" for it seems to me better to use the 



