Essays on some unsettled Questions of Political Economy

by John Stuart Mill

Of this character is the science of Political Economy in the writings of its best teachers. To render it perfect as an abstract science, the combinations of circumstances which it assumes, in order to trace their effects, should embody all the circumstances that are common to all cases whatever, and likewise all the circumstances that are common to any important class of cases. The conclusions correctly deduced from these assumptions, would be as true in the abstract as those of mathematics; and would be as near an approximation as abstract truth can ever be, to truth in the concrete.

When the principles of Political Economy are to be applied to a particular ease, then it is necessary to take into account all the individual circumstances of that case; not only examining to which of the sets of circumstances contemplated by the abstract science the circumstances of the case in question correspond, but likewise what other circumstances may exist in that case, which not being common to it with any large and strongly-marked class of cases, have not fallen under the cognizance of the science. These circumstances have been called disturbing causes. And here only it is that an element of uncertainty enters into the process—an uncertainty inherent in the nature of these complex phenomena, and arising from the impossibility of being quite sure that all the circumstances of the particular case are known to us sufficiently in detail, and that our attention is not unduly diverted from any of them.

This constitutes the only uncertainty of Political Economy; and not of it alone, but of the moral sciences in general. When the disturbing causes are known, the allowance necessary to be made for them detracts in no way from scientific precision, nor constitutes any deviation from the à priori method. The disturbing causes are not handed over to be dealt with by mere conjecture. Like friction in mechanics, to which they have been often compared, they may at first have been considered merely as a non-assignable deduction to be made by guess from the result given by the general principles of science; but in time many of them are brought within the pale of the abstract science itself, and their effect is found to admit of as accurate an estimation as those more striking effects which they modify. The disturbing causes have their laws, as the causes which are thereby disturbed have theirs; and from the laws of the disturbing causes, the nature and amount of the disturbance may be predicted à priori, like the operation of the more general laws which they are said to modify or disturb, but with which they might more properly be said to be concurrent. The effect of the special causes is then to be added to, or subtracted from, the effect of the general ones.

These disturbing causes are sometimes circumstances which operate upon human conduct through the same principle of human nature with which Political Economy is conversant, namely, the desire of wealth, but which are not general enough to be taken into account in the abstract science. Of disturbances of this description every political economist can produce many examples. In other instances the disturbing cause is some other law of human nature. In the latter case it never can fall within the province of Political Economy; it belongs to some other science; and here the mere political economist, he who has studied no science but Political Economy, if he attempt to apply his science to practice, will fail. [^[11]]

As for the other kind of disturbing causes, namely those which operate through the same law of human nature out of which the general principles of the science arise, these might always be brought within the pale of the abstract science if it were worth while; and when we make the necessary allowances for them in practice, if we are doing anything but guess, we are following out the method of the abstract science into minuter details; inserting among its hypotheses a fresh and still more complex combination of circumstances, and so adding pro hác vice a supplementary chapter or appendix, or at least a supplementary theorem, to the abstract science.

Having now shown that the method à priori in Political Economy, and in all the other branches of moral science, is the only certain or scientific mode of investigation, and that the à posteriori method, or that of specific experience, as a means of arriving at truth, is inapplicable to these subjects, we shall be able to show that the latter method is notwithstanding of great value in the moral sciences; namely, not as a means of discovering truth, but of verifying it, and reducing to the lowest point that uncertainty before alluded to as arising from the complexity of every particular case, and from the difficulty (not to say impossibility) of our being assured à priori that we have taken into account all the material circumstances.

If we could be quite certain that we knew all the facts of the particular case, we could derive little additional advantage from specific experience. The causes being given, we may know what will be their effect, without an actual trial of every possible combination; since the causes are human feelings, and outward circumstances fitted to excite them: and, as these for the most part are, or at least might be, familiar to us, we can more surely judge of their combined effect from that familiarity, than from any evidence which can be elicited from the complicated and entangled circumstances of an actual experiment. If the knowledge what are the particular causes operating in any given instance were revealed to us by infallible authority, then, if our abstract science were perfect, we should become prophets. But the causes are not so revealed: they are to be collected by observation; and observation in circumstances of complexity is apt to be imperfect. Some of the causes may lie beyond observation; many are apt to escape it, unless we are on the look-out for them; and it is only the habit of long and accurate observation which can give us so correct a preconception what causes we are likely to find, as shall induce us to look for them in the right quarter. But such is the nature of the human understanding, that the very fact of attending with intensity to one part of a thing, has a tendency to withdraw the attention from the other parts. We are consequently in great danger of adverting to a portion only of the causes which are actually at work. And if we are in this predicament, the more accurate our deductions and the more certain our conclusions in the abstract, (that is, making abstraction of all circumstances except those which form part of the hypothesis,) the less we are likely to suspect that we are in error: for no one can have looked closely into the sources of fallacious thinking without being deeply conscious that the coherence, and neat concatenation of our philosophical systems, is more apt than we are commonly aware to pass with us as evidence of their truth.

We cannot, therefore, too carefully endeavour to verify our theory, by comparing, in the particular cases to which we have access, the results which it would have led us to predict, with the most trustworthy accounts we can obtain of those which have been actually realized. The discrepancy between our anticipations and the actual fact is often the only circumstance which would have drawn our attention to some important disturbing cause which we had overlooked. Nay, it often discloses to us errors in thought, still more serious than the omission of what can with any propriety be termed a disturbing cause. It often reveals to us that the basis itself of our whole argument is insufficient; that the data, from which we had reasoned, comprise only a part, and not always the most important part, of the circumstances by which the result is really determined. Such oversights are committed by very good reasoners, and even by a still rarer class, that of good observers. It is a kind of error to which those are peculiarly liable whose views are the largest and most philosophical: for exactly in that ratio are their minds more accustomed to dwell upon those laws, qualities, and tendencies, which are common to large classes of cases, and which belong to all place and all time; while it often happens that circumstances almost peculiar to the particular case or era have a far greater share in governing that one case.

Although, therefore, a philosopher be convinced that no general truths can be attained in the affairs of nations by the à posteriori road, it does not the less behove him, according to the measure of his opportunities, to sift and scrutinize the details of every specific experiment. Without this, he may be an excellent professor of abstract science; for a person may be of great use who points out correctly what effects will follow from certain combinations of possible circumstances, in whatever tract of the extensive region of hypothetical cases those combinations may be found. He stands in the same relation to the legislator, as the mere geographer to the practical navigator; telling him the latitude and longitude of all sorts of places, but not how to find whereabouts he himself is sailing. If, however, he does no more than this, he must rest contented to take no share in practical politics; to have no opinion, or to hold it with extreme modesty, on the applications which should be made of his doctrines to existing circumstances.

No one who attempts to lay down propositions for the guidance of mankind, however perfect his scientific acquirements, can dispense with a practical knowledge of the actual modes in which the affairs of the world are carried on, and an extensive personal experience of the actual ideas, feelings, and intellectual and moral tendencies of his own country and of his own age. The true practical statesman is he who combines this experience with a profound knowledge of abstract political philosophy. Either acquirement, without the other, leaves him lame and impotent if he is sensible of the deficiency; renders him obstinate and presumptuous if, as is more probable, he is entirely unconscious of it.