If, therefore, Political Economy be a science, it cannot be a collection of practical rules; though, unless it be altogether a useless science, practical rules must be capable of being founded upon it. The science of mechanics, a branch of natural philosophy, lays down the laws of motion, and the properties of what are called the mechanical powers. The art of practical mechanics teaches how we may avail ourselves of those laws and properties, to increase our command over external nature. An art would not be an art, unless it were founded upon a scientific knowledge of the properties of the subject-matter: without this, it would not be philosophy, but empiricism; [Greek: empeiria,] not [Greek: technae,] in Plato's sense. Rules, therefore, for making a nation increase in wealth, are not a science, but they are the results of science. Political Economy does not of itself instruct how to make a nation rich; but whoever would be qualified to judge of the means of making a nation rich, must first be a political economist.
2. The definition most generally received among instructed persons, and laid down in the commencement of most of the professed treatises on the subject, is to the following effect:—That Political Economy informs us of the laws which regulate the production, distribution, and consumption of wealth. To this definition is frequently appended a familiar illustration. Political Economy, it is said, is to the state, what domestic economy is to the family.
This definition is free from the fault which we pointed out in the former one. It distinctly takes notice that Political Economy is a science and not an art; that it is conversant with laws of nature, not with maxims of conduct, and teaches us how things take place of themselves, not in what manner it is advisable for us to shape them, in order to attain some particular end.
But though the definition is, with regard to this particular point, unobjectionable, so much can scarcely be said for the accompanying illustration; which rather sends back the mind to the current loose notion of Political Economy already disposed of. Political Economy is really, and is stated in the definition to be, a science: but domestic economy, so far as it is capable of being reduced to principles, is an art. It consists of rules, or maxims of prudence, for keeping the family regularly supplied with what its wants require, and securing, with any given amount of means, the greatest possible quantity of physical comfort and enjoyment. Undoubtedly the beneficial result, the great practical application of Political Economy, would be to accomplish for a nation something like what the most perfect domestic economy accomplishes for a single household: but supposing this purpose realised, there would be the same difference between the rules by which it might be effected, and Political Economy, which there is between the art of gunnery and the theory of projectiles, or between the rules of mathematical land-surveying and the science of trigonometry.
The definition, though not liable to the same objection as the illustration which is annexed to it, is itself far from unexceptionable. To neither of them, considered as standing at the head of a treatise, have we much to object. At a very early stage in the study of the science, anything more accurate would be useless, and therefore pedantic. In a merely initiatory definition, scientific precision is not required: the object is, to insinuate into the learner's mind, it is scarcely material by what means, some general preconception of what are the uses of the pursuit, and what the series of topics through which he is about to travel. As a mere anticipation or ébauche of a definition, intended to indicate to a learner as much as he is able to understand before he begins, of the nature of what is about to be taught to him, we do not quarrel with the received formula. But if it claims to be admitted as that complete definitio or boundary-line, which results from a thorough exploring of the whole extent of the subject, and is intended to mark the exact place of Political Economy among the sciences, its pretension cannot be allowed.
"The science of the laws which regulate the production, distribution, and consumption of wealth." The term wealth is surrounded by a haze of floating and vapoury associations, which will let nothing that is seen through them be shewn distinctly. Let us supply its place by a periphrasis. Wealth is defined, all objects useful or agreeable to mankind, except such as can be obtained in indefinite quantity without labour. Instead of all objects, some authorities say, all material objects: the distinction is of no moment for the present purpose.
To confine ourselves to production: If the laws of the production of all objects, or even of all material objects, which are useful or agreeable to mankind, were comprised in Political Economy, it would be difficult to say where the science would end: at the least, all or nearly all physical knowledge would be included in it. Corn and cattle are material objects, in a high degree useful to mankind. The laws of the production of the one include the principles of agriculture; the production of the other is the subject of the art of cattle-breeding, which, in so far as really an art, must be built upon the science of physiology. The laws of the production of manufactured articles involve the whole of chemistry and the whole of mechanics. The laws of the production of the wealth which is extracted from the bowels of the earth, cannot be set forth without taking in a large part of geology.
When a definition so manifestly surpasses in extent what it professes to define, we must suppose that it is not meant to be interpreted literally, though the limitations with which it is to be understood are not stated.
Perhaps it will be said, that Political Economy is conversant with such only of the laws of the production of wealth as are applicable to all kinds of wealth: those which relate to the details of particular trades or employments forming the subject of other and totally distinct sciences.
If, however, there were no more in the distinction between Political Economy and physical science than this, the distinction, we may venture to affirm, would never have been made. No similar division exists in any other department of knowledge. We do not break up zoology or mineralogy into two parts; one treating of the properties common to all animals, or to all minerals; another conversant with the properties peculiar to each particular species of animals or minerals. The reason is obvious; there is no distinction in kind between the general laws of animal or of mineral nature and the peculiar properties of particular species. There is as close an analogy between the general laws and the particular ones, as there is between one of the general laws and another: most commonly, indeed, the particular laws are but the complex result of a plurality of general laws modifying each other. A separation, therefore, between the general laws and the particular ones, merely because the former are general and the latter particular, would run counter both to the strongest motives of convenience and to the natural tendencies of the mind. If the case is different with the laws of the production of wealth, it must be because, in this case, the general laws differ in kind from the particular ones. But if so, the difference in kind is the radical distinction, and we should find out what that is, and found our definition upon it.