Why Do We Believe What Science Says? 31 



yet convinced us that you have shown that cigarette smok- 

 ing and lung cancer are related in such a way that the 

 incidence of the disease will significantly decline if people 

 abstain from smoking in the future. We remain uncon- 

 vinced because there is still a reasonable possibility that 

 the kind of relationship your statistics have demonstrated 

 can be explained on the basis of coincidence such as that 

 represented by Descartes's two clocks." More simply stated, 

 the result may be attributable to the fact that the same 

 type of person who gets cancer is the same kind of person 

 who smokes a lot and that the two tendencies are related 

 to some common factor in the person's constitution. 



Fortunately there are ways of attacking this problem 

 and efforts are already being made to identify constitu- 

 tional or personality factors in smokers and nonsmokers 

 and in cancer and noncancer patients to see how they 

 line up. There is an even more convincing experiment 

 that might but probably won't be done. All the teen-agers 

 in this generation might find the evidence so far collected 

 quite persuasive and abstain from taking up the habit. 

 Thirty years from now the lung cancer rate might or might 

 not return to somewhere near what it was in the 1920's 

 and we would have our answer. Incidentally, I feel that the 

 weight of the evidence is on the side of those who think that 

 if teenagers decided not to smoke, there would ultimately be 

 a substantial reduction of not only cancer of the lung but 

 many other troubles of the heart and lungs which now 

 shorten the lives of thousands of our citizens. 



The situation surrounding the tobacco hypothesis, or 

 the fluoridation of water for the protection of children's 

 teeth is no different from that involved in the acceptance 

 of any scientific theory except that there is more public 

 discussion involved. There is usually no clear moment in 

 time when a new hypothesis is agreed upon and an older 



