Why Do We Believe What Science Says? 21 



reasons which might be advanced to explain why scientists 

 gave up thinking in such terms but I shall mention only 

 two. These two reasons are quite closely related to each 

 other and may in fact boil down to the same reason. In 

 the first place, if we answer a question in terms of pur- 

 pose, we tend to shut off further questions; in point of fact, 

 this is just why we do it. When the child says, "Mother, 

 why do I have a hand?" and the mother repUes, "In order 

 to put food into your mouth, button your clothes, and 

 so forth," the child usually says "Oh," and goes on about 

 his business. Clearly Mother has saved herself an enormous 

 amount of effort when she might otherwise have had to 

 go into a discussion of how hands developed over milUons 

 of years of evolution. Aristotle saved himself perhaps a 

 thousand years of work on the mechanism of growth and 

 differentiation when he contented himself with saying that 

 the oak is the cause of the acorn's development. But it is 

 just exactly the wilHngness to undertake to describe growth 

 and development in terms of preexisting rather than future 

 events that leads to scientific progress. 



The first reason, then, for abandoning final cause as 

 an explanation is that it provides answers which are too 

 satisfactory. The sense of satisfaction produced shuts off 

 rather than stimulates further inquiry. 



The second reason is really another somewhat more 

 profound aspect of the first. The fact is that no one has 

 ever figured out a way to submit a final cause to experi- 

 mental test. How, for example, are we going to find out 

 whether the oak is the cause of the growth of the acorn? 

 We might think of cutting down all the oaks in the world 

 and seeing if acorns still sprouted and differentiated into 

 oaks, but we would immediately abandon the plan for two 

 reasons. In the first place, it would be very expensive and 

 probably illegal to do the job. Even if we could, however, 



