598 LOGIC OF THE MORAL SCIENCES. 



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. As- 

 tronomy, 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. According- 

 ly, as each effect results from tlie 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 oi'der, 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 al- 

 most unmanageable complexity, and could be obtained from theory alone. 

 The generalizations which can be collected on the subject from direct ob- 

 servation, even such as Kepler's law, are mere approximations ; 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 in- 

 quiry. 



The same example shows how little can be inferred against the univer- 

 sality 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 accoi'ding to which a class of phenomena are produced may 

 be very few and simple, and yet the effects themselves may be so various 

 and complicated that it shall be impossible to trace any regularity whatev- 

 er completely through them. For the phenomena in question may be of an 

 eminently modifiable character; insomuch that innumerable circumstances 

 are capable of influencing the effect, although they may all do it according 

 to a very small number of laws. Suppose that all which passes in the mind 

 of man is determined by a few simple laws ; still, if those laws be such that 

 there is not one of the facts surrounding a human being, or of the events 

 which happen to him, that does not influence in some mode or degree his 

 subsequent mental history, and if the circumstances of different human be- 

 ings are extremely different, it will be no wonder if very few propositions 

 can be made respecting the details of their conduct or feelings, which will 

 be true of all mankind. 



Now, without deciding whether the ultimate laws of our mental nature 

 are few or many, it is at least certain that they are of the above description. 

 It is certain that our mental states, and our mental capacities and suscepti- 

 bilities, are modified, either for a time or permanently, by every thing which 

 happens to us in life. Considering, therefore, how much these modifying 

 causes differ in the case of any two individuals, it would be unreasonable 

 to expect that the empirical laws of the human mind, the generalizations 

 which can be made respecting the feelings or actions of mankind without 

 reference to the causes that determine them, should be any thing but ap- 

 proximate generalizations. They are the common wisdom of common life, 

 and as such are invaluable ; especially as they are mostly to be applied to 

 cases not very dissimilar to those from which they were collected. But 

 when maxims of this sort, collected from Englishmen, come to be applied 

 to Frenchmen, or when those collected from the present day are applied 

 to past or future generations, they are apt to be very much at fault. Un- 

 less we have resolved the empirical law into the laws of the causes on which 

 it depends, and ascertained that those causes extend to the case which we 

 have in view, there can be no reliance placed in our inferences. For every 



