ETHOLOGY. 447 



The really scientific truths, then, are not these empirical 

 laws, but the causal laws which explain them. The empirical 

 laws of those phenomena which depend on known causes, and 

 of which a general theory can therefore be constructed, have, 

 whatever may be their value in practice, no other function in 

 science than that of verifying the conclusions of theory. Still 

 more must this be the case when most of the empirical laws 

 amount, even within the limits of observation, only to approxi- 

 mate generalizations. 



2. This however is not, so much as is sometimes sup- 

 posed, a peculiarity of the sciences called moral. It is only 

 in the simplest branches of science that empirical laws are 

 ever exactly true; and not always in those. Astronomy, for 

 example, is the simplest of all the sciences which explain, in 

 the concrete, the actual course of natural events. The causes 

 or forces, on which astronomical phenomena depend, are fewer 

 in number than those which determine any other of the great 

 phenomena of nature. Accordingly, as each effect results 

 from the conflict of but few causes, a great degree of regularity 

 and uniformity might be expected to exist among the effects ; 

 and such is really the case : they have a fixed order, and 

 return in cycles. But propositions which should express, with 

 absolute correctness, all the successive positions of a planet 

 until the cycle is completed, would be of almost unmanageable 

 complexity, and could be obtained from theory alone. The 

 generalizations which can be collected on the subject from 

 direct observation, even such as Kepler's law, are mere ap- 

 proximations : the planets, owing to their perturbations by 

 one another, do not move in exact ellipses. Thus even in 

 astronomy, perfect exactness in the mere empirical laws is not 

 to be looked for; much less, then, in more complex subjects 

 of inquiry. 



The same example shows how little can be inferred against 

 the universality or even the simplicity of the ultimate laws, 

 from the impossibility of establishing any but approximate 

 empirical laws of the effects. The laws of causation according 

 to which a class of phenomena are produced may be very few 



