19R THE PRINCIPLES OF SCIENCE. [CHAP. 



Chance cannot be the subject of the theory, because 

 there is really no such thing as chance, regarded as pro- 

 ducing and governing events. The word chance signifies 

 falling, and the notion of falling is continually used as a 

 simile to express uncertainty, because we can seldom pre- 

 dict how a die, a coin, or a leaf will fall, or when a bullet 

 will hit the mark. But everyone sees, after a little 

 reflection, that it is in our knowledge the deficiency lies, 

 not in the certainty of nature's laws. There is no doubt in 

 lightning as to the point it shall strike; in the greatest 

 storm there is nothing capricious ; not a grain of sand lies 

 upon the beach, but infinite knowledge would account for 

 its lying there ; and the course of every falling leaf is 

 guided by the principles of mechanics which rule the 

 motions of the heavenly bodies. 



Chance then exists not in nature, and cannot coexist 

 with knowledge ; it is merely an expression, as Laplace 

 remarked, for our ignorance of the causes in action, and 

 our consequent inability to predict the result, or to bring 

 it about infallibly. In nature the happening of an event 

 has. been pre-determined from the first fashioning of the 

 universe. Probability belongs wholly to the mind. This is 

 proved by the fact that different minds may regard the 

 very same event at the same time with widely different 

 degrees of probability. A steam-vessel, for instance, is 

 missing and some persons believe that she has sunk in 

 mid-ocean ; others think differently. In the event itself 

 there can be no such uncertainty ; the steam-vessel either 

 has sunk or has not sunk, and no subsequent discussion of 

 the probable nature of the event can alter the fact. Yet 

 the probability of the event will really vary from day to 

 day, and from mind to mind, according as the slightest 

 information is gained regarding the vessels met at sea, the 

 weather prevailing there, the signs of wreck picked up, 

 or the previous condition of the vessel. Probability thus 

 belongs to our mental condition, to the light in which we 

 regard events, the occurrence or non-occurrence of which 

 is certain in themselves. Many writers accordingly have 

 asserted that probability is concerned with degree or 

 quantity of belief. De Morgan says, 1 " By degree of proba- 



1 Formal Logic, p. 172. 



