The reflections into which we have entered upon the laws of the universe not only afford a simple and impressive argument in favour of the doctrine of necessity, but suggest a very obvious reason why the doctrine opposite to this has been, in a certain degree, the general opinion of mankind.
It has appeared that the idea of uniform conjunction between events of any sort is the lesson of experience, and the vulgar never arrive at the universal application of this principle even to the phenomena of the material universe. In the easiest and most familiar instances, such as the impinging of one ball of matter upon another and its consequences, they willingly admit the interference of chance and irregularity. In this instance however, as both the impulse and its consequences are subjects of observation to the senses, they readily imagine that they perceive the absolute principle which causes motion to be communicated from the first ball to the second.
Now the very same prejudice and precipitate conclusion, which induce them to believe that they discover the principle of motion in objects of sense, act in an opposite direction with respect to such objects as cannot be subjected to the examination of sense. The power by which a sensation, pleasurable or painful, when presented to the mind of a percipient being, produces volition and animal motion, no one can imagine that he sees; and therefore they readily conclude that there is no uniformity of conjunction in these events.
But, if the vulgar will universally be found to be the advocates of free will, they are not less strongly, however inconsistently, impressed with the belief of the doctrine of necessity. It is a well known and a just observation that, were it not for the existence of general laws to which the events of the material universe always conform, man could never have been either a reasoning or a moral being. The most considerable actions of our lives are directed by foresight. It is because he foresees the regular succession of the seasons that the farmer sows his field, and, after the expiration of a certain term, expects a crop. There would be no kindness in my administering food to the hungry, and no injustice in my thrusting a drawn sword against the bosom of my friend, if it were not the established quality of food to nourish, and of a sword to wound.