An Enquiry Concerning Human Understanding

Hume begins by defining his terms and setting the foundation for what’s to come. His first step toward gaining insight into the workings of the human mind is to distinguish what he calls moral philosophy from any other kind of science; moral philosophy, as he defines it, is specifically concerned with human nature. The use of the word “science” in his writing is not synonymous with how it is used in a modern context, but simply means a field of knowledge.

Hume divides moral philosophy into two sections. The first views mankind as primarily geared up for action: It looks at human action and virtue as that which is best able to define and perfect human nature. This approach privileges stories and poetry. It is appealing to the average person in that it is easy to understand and excites the emotions. The contrasting approach to philosophy is one that the average person generally neglects and denigrates because it is opaque and difficult to understand. It is concerned not with action, but with precision and depth.

This latter approach is extremely difficult; only a few can appreciate or attempt it. This, however, is precisely what Hume sets out to do. Even though the conclusions of an abstract thinker are often considered “unintelligible” (4), they are the means to true wisdom and knowledge. Those who practice abstract thinking are considered to be simple philosophers, contributing nothing to society the way that an entertainer or teacher or someone more practical would. The benefits of this more difficult path, however, will greatly surpass any other philosophical approach because of commitment to precision and accuracy. Hume gives the example of someone studying anatomy. He says that it’s the anatomist’s attention to detail that allows an artist to paint such delicate and accurate figures, on account of the knowledge gained of the human body’s proportions and makeup.

Every human industry and activity will benefit from the precision and detail that comes from the more difficult mode of philosophy and will allow them to come nearer to perfection. Hume feels that his work will naturally spread throughout society and bring benefits to all, even where its effects are not expected or detected. The human mind will be more perfectly and truthfully outlined and described in his own work; the “task of ordering and distinguishing” the various powers of the mind will be the task at hand (9).

Hume distinguishes between ideas and impressions. Often the two are conflated and confused in common speech and thinking, but they are quite different. Impressions, argues Hume, are the origin of all our ideas. They exist most vividly in contrast with the dull shadow of our ideas, which we see in his example of being burned versus the memory of being burned—the former is an impression, and the latter is an idea.

People usually think that ideas are much greater than impressions due to their potentially infinite and limitless quality—one can think of anything, imagine anything, remember anything. According to Hume, it is the opposite. No idea will ever be as forceful as an impression. Every single idea that a person has originates from an impression, an experience that they had. One can only imagine heat because they experienced it first; it has natural priority.

Hume shows that every single idea one has is always connected to all one’s other ideas, for “even in our wildest and most wandering reveries” there is some connecting thread (16). There are three categories of connection. First, the category of resemblance, where one thing resembles another thing in some accidental quality—color, sound, smell. The second category is that of contiguity, where we think of one thing because it has proximity to another, like thinking of one’s garden and then thinking of the flowers within that garden. The third category is that of cause and effect, where every effect is thought to spring intrinsically and necessarily from a prior cause. In succeeding chapters, Hume will argue against ancient philosophers who held that cause is superior to effect.