• The Experimental Method and the Science of Human Nature
• The Anatomist of Morals vs The Painter of Virtue

The Experimental Method and the Science of Human Nature

The subtitle of the Treatise is “Being an Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects.” This is revealing. Inspired by the success of Newton’s new science (due in large part to the deployment of the experimental method that Bacon prescribed), Hume endeavored to introduce the experimental method into philosophy. Just as the deployment of experimental method in natural philosophy (by which Hume understands mechanics and astronomy and the study of nature more generally) yielded positive results, Hume believed that the deployment of experimental method in moral philosophy (by which Hume understands the study of humans and human activity) would yield positive results as well.

Hume believed that the introduction of the experimental method into philosophy and the establishment of the “science of human nature” was necessary in order to resolve persistent and apparently fruitless disagreements in philosophy:

There is nothing which is not the subject of debate, and in which men of learning are not of contrary opinions. The most trivial question escapes not our controversy, and in the most momentous we are not able to give any certain decision. Disputes are multiply’d as if everything was uncertain; and these disputes are manag’d with the greatest warmth, as if every thing was certain. (Treatise Intro, 2)

Instead of pursuing these debates directly, Hume believed that progress could be made if we first become “thouroughly acquainted with the extent and force of human understanding” (Treatise Intro, 4). To do so we should “explain the nature of the ideas we employ, and of the operations we perform in our reasonings” (Treatise Intro, 4). It is only once we understand the origin of our ideas that we can understand what we can reasonably expect to know about other subject matters. It is in this sense that Hume describes moral philosophy or the science of human nature as the “capital of the sciences”.

The new natural philosophy, given its experimental method, is based on observation, but it is no mere summary of these observations. The natural philosopher may legitimately generalize his observations. Moreover, natural philosophy aspires to establish a limited number of principles that can explain the greatest number of observed phenomena. Similarly, moral philosophy is to be based on observation, but is no mere summary of these observations. The moral philosopher may legitimately generalize his observations. Moreover, the moral philosopher aspires to establish a limited number of principles that can explain the greatest number of observed phenomena:

…we must endeavour 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… (Treatise Intro, 8)

Though the natural and moral philosopher may generalize their observations in an attempt to discover fundamental and comprehensive principles, they cannot hope to transcend experience to discover the ultimate supersensible causes of things:

…’tis still certain we cannot go beyond experience; and any hypothesis, that pretends to discover the ultimate original qualities of human nature, ought at first to be rejected as presumptuous and chimerical. (Treatise Intro, 8)

Though both natural and moral philosophy are to be based on the experimental method, there is a crucial methodological difference between these intellectual disciplines. The natural philosopher can “interrogate nature” as Bacon prescribed. The natural philosopher can conduct experiments under controlled conditions “purposely, with premeditation, and after such a manner as to satisfy itself concerning every particular difficulty which may arise”. However, in moral philosophy no such interrogation is possible. The moral philosopher cannot conduct experiments under controlled conditions. Rather, he is limited to “a cautious observation of human life, and take them as they appear in the common course of the world, by men’s behaviour in company, in affairs and in their pleasures”. Nevertheless, such cautious observations are sufficient “to establish…a science, which will not be inferior in certainty, and will be much superior in utility to any other human comprehension” (Treatise Intro, 10).

The Anatomist of Morals vs the Painter of Virtue

A central goal of the Treatise is to examine the origin of certain kinds of ideas and impressions. Book I discusses the origin of certain important ideas (of space and time, necessary connection, of external objects, and the self). Book II discusses the origin of certain impressions of reflections (the passions, desires, and the will). Book III discusses the origin of moral distinctions such as between vice and virtue. Hume will argue that moral distinctions depend on certain impressions.

Hume’s project in moral philosophy is primarily descriptive and explanatory, as opposed to being prescriptive and justificatory. Hume does not seek to prescribe certain moral judgments. Common morality is fine as it stands (though perhaps susceptible to certain refinements and extensions). Rather Hume seeks to describe how we come to make the moral judgments that we make. Hume seeks to explain the origin of our moral distinctions rather than to justify these distinctions (though Hume believes that once we recognize the proper explanation of the moral distinctions that we make, we will be all the more pleased to make them). Moreover, and importantly, Hume seeks to provide a naturalistic explanation of our moral distinctions. Hume seeks to give an account of human morality as a natural phenomena-as arising from human nature and our place in nature. He thus rejects any attempt to give a theological foundation to morality of a kind that natural law theorists (such as Locke and Puffendorf) recommended.

Hutcheson famously complained that Hume’s moral science lacked sufficient “Warmth in the Cause of Virtue”. The moral philosopher, Hume responded, must consider the human mind that gives rise to moral distinctions:

…either as an Anatomist or as a Painter; either to discover its most secret Springs & Principles or to describe the Grace & Beauty of its Actions. I imagine it impossible to conjoin these two Views. Where you pull off the Skin, & display all the minute Parts, there appears something trivial, even in the noblest Attitudes & most vigorous Actions: Nor can you ever render the object graceful or engaging but by the cloathing the Parts again with Skin & Flesh, & presenting only their bare Outside. An Anatomist, however, can give very good Advice to a Painter or Statuary: And in like manner, I am perswaded, that a Metaphysician may be very helpful to a Moralist; tho’ I cannot easily conceive these two Characters united in the same Work. Any warm Sentiment of Morals, I am afraid, would have the Air of Declamation amidst abstract Reasonings, & wou’d be esteem’d contrary to good Taste. And tho’ I am much more ambitious of being esteem’d a Friend of Virtue, than a Writer of Taste; yet I must always carry the latter in my Eye, otherwise I must despair of ever being servicable to Virtue. (Letter of 17 September, 1739)

An attitude that is perhaps reflected in the epigram of Book III:

Duræ semper virtutis amator, Quære est virtus, et posce exemplar honesti.

A lover of austere virtue, you should at least ask now what Virtue is and demand to see Goodness in her visible shape. (Lucan, Civil Wars 9.562-3)