September 22, 1916] 



SCIENCE 



419 



have dissolved the simple idea of an ex- 

 tended body, say of a chair, which a child 

 understands, into a bewildering notion of 

 a complex dance of molecules and atoms 

 and electrons and waves of light. They 

 have thereby gained notions with simpler 

 logical relations. 



Space as thus conceived is the exact for- 

 mulation of the properties of the apparent 

 space of the common-sense world of experi- 

 ence. It is not necessarily the best mode 

 of conceiving the space of the physicist. 

 The one essential requisite is that the corre- 

 spondence between the common-sense world 

 in its space and the physicists' world in its 

 space should be definite and reciprocal. 



I will now break off the exposition of the 

 function of logic in connection with the sci- 

 ence of natural phenomena. I have en- 

 deavored to exhibit it as the organizing 

 principle, analyzing the derivation of the 

 concepts from the immediate phenomena, 

 examining the structure of the general 

 propositions which are the assumed laws of 

 nature, establishing their relations to each 

 other in respect to reciprocal implications, 

 deducing the phenomena we may expect 

 under given circumstances. 



Logic, properly used, does not shackle 

 thought. It gives freedom and, above all, 

 boldness. Illogical thought hesitates to 

 draw conclusions, because it never knows 

 either what it means, or what it assumes, or 

 how far it trusts its own assumptions, or 

 what will be the effect of any modification 

 of assumptions. Also the mind untrained 

 in that part of constructive logic which is 

 relevant to the subject in hand will be 

 ignorant of the sort of conclusions which 

 follow from various sorts of assumptions, 

 and will be correspondingly dull in divin- 

 ing the inductive laws. The fundamental 

 training in this relevant logic is, un- 

 doubtedly, to ponder with an active mind 

 over the known facts of the case, directly 



observed. But where elaborate deductions 

 are possible, this mental activity requires 

 for its full exercise the direct study of the 

 abstract logical relations. This is applied 

 mathematics. 



Neither logic without observation, nor 

 observation without logic, can move one 

 step in the formation of science. We may 

 conceive humanity as engaged in an inter- 

 necine conflict between youth and age. 

 Youth is not defined by years, but by the 

 creative impulse to make something. The 

 aged are those who, before all things, desire 

 not to make a mistake. Logic is the olive 

 branch from the old to the young, the wand 

 which in the hands of youth has the magic 

 property of creating science. 



A. N. Whitehead 



DR. HALDANE'S SILLIMAN LECTURES 

 Dr. J. S. Haldane, of the University of Ox- 

 ford, gives the Silliman lectures at Tale Uni- 

 versity on October 9, 10, 12 and 13. The gen- 

 eral subject of the lectures is : Organization 

 and Environment as illustrated by the Physi- 

 ology of Breathing. The topics of the separate 

 lectures are: 



Lecture I.- — The problem presented by the co- 

 ordinated maintenance of reactions between or- 

 ganism and environment — vitalistie and mechan- 

 istic attempts at explanation; The elementary 

 facts relating to breathing; The respiratory cen- 

 ter and the blood; Alveolar air and the exact reg- 

 ulation of its CO™ percentage; Apnea and hyper- 

 pnea; Varying frequency of breathing; Physio- 

 logical effects of varying pressures of gases; Ef- 

 fects of deprivation of C0 2 ; Effects of air of con- 

 fined spaces and mines; Effects of compressed air 

 in diving; Influence of the vagus nerves in breath- 

 ing; Coordination of the responses to central and 

 peripheral nervous stimuli, so that the respiratory 

 apparatus acts as a whole. 



Lecture II. — The gases of the blood; Oxyhemo- 

 globin and the conditions of its dissociation; The 

 combinations of CO, in the blood and their dis- 

 sociation; Effects of oxygenation of hemoglobin 

 on the dissociation of C0 2 ; Exact physiological 

 regulation of the blood-gases; Evidence that COj 

 acts physiologically as an acid; Investigations of 



