CHAP. V.] OPENING MANHOOD 1847 TO 1850. 143 



>f 



of his natural liberty with respect to others, as he wishes 

 that other men should to him. Hobbes having shown that 

 men, in what the poets and moralists call a state of nature 

 (that is, of equality and liberty, and without government), 

 must be in a state of war, every man against every other, 

 and therefore of danger to every man, deduces the obligation 

 of obeying the powers that be from the necessity of Power 

 to prevent universal war. Adam Smith's theory of Moral 

 Sentiments (which is the most systematic next to Hobbes) 

 is that men desire others to sympathise with them, and 

 therefore do those things which may be sympathised with ; 

 that is, as Smith's opponents say, men ought to be guided 

 by the desire of esteem and sympathy. Not so. Smith 

 does not leave us there, but I suppose you have read him, 

 as he is almost the only Scotch Moral Philosopher. 



As it is Saturday night I will not write very much 

 more. I was thinking to-day of the duties of [the] cognitive 

 faculty. It is universally admitted that duties are voluntary, 

 and that the will governs understanding by giving or with- 

 holding Attention. They say that Understanding ought to 

 work by the rules of right reason. These rules are, or ought 

 to be, contained in Logic ; but the actual science of Logic is 

 conversant at present only with things either certain, impos- 

 sible, or entirely doubtful, none of which (fortunately) we 

 have to reason on. Therefore the true Logic for this world 

 is the Calculus of Probabilities, which takes account of the 

 magnitude of the probability (which is, or which ought to 

 be in a reasonable man's mind). This branch of Math., which 

 is generally thought to favour gambling, dicing, and wagering, 

 and therefore highly immoral, is the only " Mathematics for 

 Practical Men," as we ought to be. Now, as human knowledge 

 comes by the senses in such a way that the existence of things 

 external is only inferred from the harmonious (not similar) 

 testimony of the different senses, Understanding, acting by the 

 laws of right reason, will assign to different truths (or facts, 

 or testimonies, or what shall I call them) different degrees 

 of probability. Now, as the senses give new testimonies 

 continually, and as no man ever detected in them any real 



