Advertisement by David Hume I began with 2 books about the Understanding and the Passions as they make a complete chain of reasoning by themselves naturally. If those 2 books are successful, I shall write Book 3 on Morals, Politics, and Criticism, completing this Treatise of Human Nature. I consider: the public’s approbation as the greatest reward of my labours and the public’s judgment as my best instruction. Introduction Those who pretend to discover new things in philosophy and the sciences usually praise their own discoveries by decrying all those that came before them. Only a few scientists would readily agree with them. It is easy for a wise and learned person to perceive the weak foundation of systems which have: obtained the greatest credit, and carried their pretensions highest to an accurate and profound reasoning. The systems of the most eminent philosophers: have principles taken on trust, have consequences lamely deduced from trust, and lack coherence in parts and evidence on the whole. Their systems have drawn disgrace on philosophy itself. No profound knowledge is needed to discover the present imperfect condition of the sciences. From the noise and clamour, we see that all is not well in their systems. Everything is subject to debate and contrary opinions. We entertain the most trivial question. But we are not able to give any certain answer on the most momentous ones. Disputes are multiplied, as if everything was uncertain. These disputes are managed with the greatest warmth, as if everything was certain. Amidst all this bustle, eloquence carries the prize, not reason. The artful man uses the most extravagant hypothesis in favourable colours. He always gains converts. The victory is not gained by the soldiers, but by the army’s trumpeters, drummers, and musicians. I think this is the cause of that common prejudice against metaphysical reasonings, even among: scholars, and those who have a just value for every other part of literature. By metaphysical reasonings, they do not understand those on any particular branch of science. But they understand every kind of argument which is abstruse and requires some attention to be comprehended. We have so often lost our labour in such researches. We commonly reject them without hesitation. If we must forever be a prey to errors and delusions, we resolve that they shall at least be natural and entertaining. Only the most determined skepticism, with a great indolence, can justify this aversion to metaphysics. For if truth is within the reach of human capacity at all, it must lie very deep and abstruse. It must be vain and presumptuous to hope to arrive at it without pains, while the greatest geniuses have failed with the utmost pains. I pretend to no such advantage in the philosophy I am going to unfold. I would esteem it a strong presumption against it, were it so very easy and obvious. All the sciences have a relation to human nature. No matter how far any science runs away from human nature, it still returns by one way or another. Even Mathematics, Natural Philosophy, and Natural Religion, are in some measure dependent on the science of man, since they: lie under human cognizance, and are judged of by human powers and faculties. It is impossible to tell what changes and improvements we might make in these sciences if we: were thoroughly acquainted with the extent and force of human understanding, and could explain the nature of: the ideas we employ, and the operations we perform in our reasonings We can hope for these improvements more in natural religion because religion is not content with instructing us in the nature of superior powers. It carries its views farther to: the disposition of superior powers towards us, and our duties towards them. Consequently, we are not only the beings that reason. We are also one of the objects on which we reason. Mathematics, Natural Philosophy, and Natural Religion depend so much on the knowledge of man. The other sciences that are more intimate with human nature depend such knowledge so much more. The sole end of logic is to explain: the principles and operations of our reason, and the nature of our ideas. Logic, Morals, and Criticism explain our tastes and feelings. Politics explains how men are united in society and dependent on each other. These four sciences of Logic, Morals, Criticism, and Politics comprehends almost everything which can: be important to us, or tend to the human mind’s improvement or ornament. Here, the only expedient for success in our philosophical researches is to leave the tedious lingering method which we have followed. Instead of taking a castle or village on the frontier now and then, we march up directly to the capital or center of these sciences, to human nature itself. Once we master human nature, we may hope for an easy victory everywhere else. From here, we may extend our conquests over all those sciences, which more intimately concern human life. We may afterwards proceed at leisure to discover more fully those which are the objects of curiosity. All answers to important questions are comprised in the science of man. No question can be answered with any certainty, before we become acquainted with that science. In pretending, therefore, to explain the principles of human nature, we in effect propose a complete system of the sciences. This system is built on an almost entirely new foundation. This foundation is the only one on which the sciences can be secured. The science of man is the only solid foundation for the other sciences. The only solid foundation we can give to this science must be laid on experience and observation. It is not astonishing for moral philosophy to come after natural philosophy. We find that there was around the same interval between the origins of these sciences. The time between Thales to Socrates is nearly equal to that between Francis Bacon and some recent English philosophers such as: John Locke Lord Shaftesbury Bernard Mandeville Francis Hutcheson Joseph Butler, etc. Those recent philosophers have: begun to put the science of man on a new footing, and engaged the public attention and curiosity. Other nations may: rival us in poetry, or excel us in some other agreeable arts. But the improvements in reason and philosophy can only be owing to a land of toleration and of liberty. We should not think that this improvement in the science of man will do less honour to our native country than the excellence in natural philosophy. We should rather esteem this improvement a greater glory because of: the greater importance of the science of man, and the need to reform it. The essence of the mind is equally unknown to us as the essence of external bodies. It must be equally impossible to form any notion of the mind’s powers and qualities unless we: do careful and exact experiments, and observe those particular effects which result from its different circumstances and situations. We must try to render all our principles as universal as possible by: tracing up our experiments to the utmost, and explaining all effects from the simplest and fewest causes. But we cannot go beyond experience. Any hypothesis that pretends to discover the ultimate original qualities of human nature should at first be rejected as presumptuous and chimerical. I do not think that a philosopher would show himself as a great master in the science of human nature, if he applies himself so earnestly to explain the ultimate principles of the soul. Such an earnest philosopher would not pretend to explain or be very knowing in what is naturally satisfactory to the mind of man. Despair has almost the same effect on us with enjoyment. We are no sooner acquainted with the impossibility of satisfying any desire, than the desire itself vanishes. When we have arrived at the utmost extent of human reason, we sit down contented, even if we: are perfectly satisfied at our ignorance, and can give no reason for our most general and refined principles, besides our experience of their reality. Their reality is a mere vulgar reason. It required no study at first to have discovered for the most particular and extraordinary phenomenon. This impossibility of making any further progress is enough to satisfy the reader, so the writer may derive a more delicate satisfaction from: the free confession of his ignorance, and his prudence in avoiding that error into which so many have fallen. This error is in imposing their conjectures and hypotheses on the world for the most certain principles. When this mutual contentment and satisfaction can be obtained between the master and scholar, nothing else is required of our philosophy. But if this impossibility of explaining ultimate principles should be esteemed a defect in the science of man, it is a defect common to all the sciences and arts, whether those: in the schools of the philosophers, or practised in the shops of the meanest artisans. None of them can: go beyond experience, or establish any principles not founded on experience. Moral philosophy has this peculiar disadvantage not found in natural philosophy. In collecting its experiments, it cannot make them purposely with premeditation. If it does, it cannot satisfy itself on every difficulty. When I want to know the effects of one body on another in any situation, I only need to: put them in that situation, and observe the results. But if I try to clear up any doubt in moral philosophy by placing myself in the same case with that which I consider, this reflection and premeditation would disturb the operation of my natural principles. It would be impossible to form any just conclusion from the phenomenon. We must therefore glean up our experiments in this science from a cautious observation of human life. We must take them as they appear in the common course of the world, by men’s behaviour: in company, in affairs, and in their pleasures. If experiments of this kind are judiciously collected and compared, we can establish a science on them which will: not be inferior in certainty, and be more useful to any other science of human comprehension.