A man is practising at a target with a gun, when a rabbit crosses his line of fire. The man has his eye and his sights on the rabbit, and his finger on the trigger. The man's will is free. If he press the trigger the rabbit will be killed.
Now, how does the man decide whether or not he shall fire? He decides by feeling, and by reason.
He would like to fire, just to make sure that he could hit the mark. He would like to fire, because he would like to have the rabbit for supper. He would like to fire, because there is in him the old, old hunting instinct, to kill.
But the rabbit does not belong to him. He is not sure that he will not get into trouble if he kills it. Perhaps—if he is a very uncommon kind of man—he feels that it would be cruel and cowardly to shoot a helpless rabbit.
Well. The man's will is free. He can fire if he likes: he can let the rabbit go if he likes. How will he decide? On what does his decision depend?
His decision depends upon the relative strength of his desire to kill the rabbit, and of his scruples about cruelty, and the law. Not only that, but, if we knew the man fairly well, we could guess how his free will would act before it acted. The average spoiling Briton would kill the rabbit. But we know that there are men who would on no account shoot any harmless wild creature.
Broadly put, we may say that the sportsman would will to fire, and that the humanitarian would not will to fire.
Now, as both their wills are free, it must be something outside the wills that makes the difference.
Well. The sportsman will kill, because he is a sportsman: the humanitarian will not kill, because he is a humanitarian.
And what makes one man a sportsman and another a humanitarian? Heredity and environment: temperament and training.