The author asserts that it would be of no use if the meaning of the underlying question could not be affixed by the arbitrators. The same problem, according to the author, plagues the problem of liberty and necessity. Hume argues that doctrine both of necessity and liberty hold true.
Hume starts off by defining necessity as uniformity arising from constant conjunction and "custom to infer the one from the appearance of other". He reiterates the commonly agreed theory that matter is governed by necessity and hence easy to determine what effect will take place with a cause. For each situation, looking at the forces of nature, their direction and their strength, it should then be possible to predict any action for matter. If everyone agrees that there is regular conjunction and a custom to infer in the case of voluntary actions of men, then necessity hold for voluntary human actions and men have merely argued upon not understanding.
Hume goes on to say that it has been noted that there is a "great uniformity" in the actions of men. Hume argues that the "human nature remain still the same, in its principles and operations" and that the "same motives always produce the same actions". Experience guides us in making decision in different situations which might be our own experience or experience gathered by men. Hume says that there might be cases of exceptions, cases of "no regular connection with any known motives" but if we willingly knew what judgments to form we may entertain the common sentiments in regard to those cases. Thus we see that regular conjunction between motives and voluntary actions of men and a custom to infer has been established. Thus, necessity hold true for voluntary human actions.
Hume goes on further to define liberty as the power of acting or not acting according to the determinations of the will of a being. Hume asserts that everyone will side with this view and since deliberations based on will are possible, liberty holds true.