How Science Works 43 



obvious to us as a matter of subjective experience. The 

 future of the hfe sciences holds many challenges but per- 

 haps no greater one than the resolution of this paradox — 

 the clear subjective existence of consciousness and its in- 

 accessibility to objective description. 



From time to time some scientists have been either so 

 distressed over the difficulty of understanding systems of 

 organized complexity or so overawed by the mystery of 

 life that they have suggested that life processes differ in 

 some basic way from the phenomena studied in physics 

 and chemistry. This school of thought (sometimes known 

 as vitahsm) has always been handicapped by its inability 

 to state its beliefs in a form susceptible to experimental 

 test. Conversely, the so-called mechanistic or mechanical 

 view of life has produced a long series of experiments 

 which have made it possible to explain most, if not all, 

 living processes in terms of antecedent events of a physical 

 or chemical nature. The early triumphs of the method came 

 in the sixteenth century when such purely mechanical 

 matters as the movements of the arms and legs were found 

 to obey the physical laws of motion. For example, con- 

 siderable pleasure was evoked by this school in noting that 

 the various bones represented levers of all three classes. 

 The vitalists then erected their defenses on a chemical point 

 and said that only living things could synthesize certain 

 sorts of substances with carbon as one of their important 

 constituents and known as organic compounds. The Ger- 

 man chemist, Wohler, demolished this barrier by synthe- 

 sizing urea in 1828 and now there seems to be no Umit to 

 what can be made in a test tube. After Wohler, a long 

 train of investigators demonstrated that living things pre- 

 cisely obey the laws of conservation of mass and energy 

 characteristic of the nonliving world. Remnants of the op- 

 posing vitaHstic view still crop up from time to time in such 



