No mathematician ever thought that his definition of a line corresponded to an actual line. As little did any political economist ever imagine that real men had no object of desire but wealth, or none which would not give way to the slightest motive of a pecuniary kind. But they were justified in a.s.suming this, for the purposes of their argument; because they had to do only with those parts of human conduct which have pecuniary advantage for their direct and princ.i.p.al object; and because, as no two individual cases are exactly alike, no _general_ maxims could ever be laid down unless _some_ of the circ.u.mstances of the particular case were left out of consideration.
But we go farther than to affirm that the method _a priori_ is a legitimate mode of philosophical investigation in the moral sciences: we contend that it is the only mode. We affirm that the method _a posteriori_, or that of specific experience, is altogether inefficacious in those sciences, as a means of arriving at any considerable body of valuable truth; though it admits of being usefully applied in aid of the method _a priori_, and even forms an indispensable supplement to it.
There is a property common to almost all the moral sciences, and by which they are distinguished from many of the physical; this is, that it is seldom in our power to make experiments in them. In chemistry and natural philosophy, we can not only observe what happens under all the combinations of circ.u.mstances which nature brings together, but we may also try an indefinite number of new combinations. This we can seldom do in ethical, and scarcely ever in political science. We cannot try forms of government and systems of national policy on a diminutive scale in our laboratories, shaping our experiments as we think they may most conduce to the advancement of knowledge. We therefore study nature under circ.u.mstances of great disadvantage in these sciences; being confined to the limited number of experiments which take place (if we may so speak) of their own accord, without any preparation or management of ours; in circ.u.mstances, moreover, of great complexity, and never perfectly known to us; and with the far greater part of the processes concealed from our observation.
The consequence of this unavoidable defect in the materials of the induction is, that we can rarely obtain what Bacon has quaintly, but not unaptly, termed an _experimentum crucis_.
In any science which admits of an unlimited range of arbitrary experiments, an _experimentum crucis_ may always be obtained. Being able to vary all the circ.u.mstances, we can always take effectual means of ascertaining which of them are, and which are not, material. Call the effect B, and let the question be whether the cause A in any way contributes to it. We try an experiment in which all the surrounding circ.u.mstances are altered, except A alone: if the effect B is nevertheless produced, A is the cause of it. Or, instead of leaving A, and changing the other circ.u.mstances, we leave all the other circ.u.mstances and change A: if the effect B in that case does _not_ take place, then again A is a necessary condition of its existence. Either of these experiments, if accurately performed, is an _experimentum crucis_; it converts the presumption we had before of the existence of a connection between A and B into proof, by negativing every other hypothesis which would account for the appearances.
But this can seldom be done in the moral sciences, owing to the immense mult.i.tude of the influencing circ.u.mstances, and our very scanty means of varying the experiment. Even in operating upon an individual mind, which is the case affording greatest room for experimenting, we cannot often obtain a _crucial_ experiment. The effect, for example, of a particular circ.u.mstance in education, upon the formation of character, may be tried in a variety of cases, but we can hardly ever be certain that any two of those cases differ in all their circ.u.mstances except the solitary one of which we wish to estimate the influence. In how much greater a degree must this difficulty exist in the affairs of states, where even the _number_ of recorded experiments is so scanty in comparison with the variety and mult.i.tude of the circ.u.mstances concerned in each. How, for example, can we obtain a crucial experiment on the effect of a restrictive commercial policy upon national wealth? We must find two nations alike in every other respect, or at least possessed, in a degree exactly equal, of everything which conduces to national opulence, and adopting exactly the same policy in all their other affairs, but differing in this only, that one of them adopts a system of commercial restrictions, and the other adopts free trade. This would be a decisive experiment, similar to those which we can almost always obtain in experimental physics. Doubtless this would be the most conclusive evidence of all if we could get it. But let any one consider how infinitely numerous and various are the circ.u.mstances which either directly or indirectly do or may influence the amount of the national wealth, and then ask himself what are the probabilities that in the longest revolution of ages two nations will be found, which agree, and can be shown to agree, in all those circ.u.mstances except one?
Since, therefore, it is vain to hope that truth can be arrived at, either in Political Economy or in any other department of the social science, while we look at the facts in the concrete, clothed in all the complexity with which nature has surrounded them, and endeavour to elicit a general law by a process of induction from a comparison of details; there remains no other method than the _a priori_ one, or that of "abstract speculation."
Although sufficiently ample grounds are not afforded in the field of politics, for a satisfactory induction by a comparison of the effects, the causes may, in all cases, be made the subject of specific experiment. These causes are, laws of human nature, and external circ.u.mstances capable of exciting the human will to action. The desires of man, and the nature of the conduct to which they prompt him, are within the reach of our observation. We can also observe what are the objects which excite those desires. The materials of this knowledge every one can princ.i.p.ally collect within himself; with reasonable consideration of the differences, of which experience discloses to him the existence, between himself and other people. Knowing therefore accurately the properties of the substances concerned, we may reason with as much certainty as in the most demonstrative parts of physics from any a.s.sumed set of circ.u.mstances. This will be mere trifling if the a.s.sumed circ.u.mstances bear no sort of resemblance to any real ones; but if the a.s.sumption is correct as far as it goes, and differs from the truth no otherwise than as a part differs from the whole, then the conclusions which are correctly deduced from the a.s.sumption const.i.tute _abstract_ truth; and when completed by adding or subtracting the effect of the non-calculated circ.u.mstances, they are true in the concrete, and may be applied to practice.
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 circ.u.mstances which it a.s.sumes, in order to trace their effects, should embody all the circ.u.mstances that are common to all cases whatever, and likewise all the circ.u.mstances that are common to any important cla.s.s of cases. The conclusions correctly deduced from these a.s.sumptions, 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 circ.u.mstances of that case; not only examining to which of the sets of circ.u.mstances contemplated by the abstract science the circ.u.mstances of the case in question correspond, but likewise what other circ.u.mstances may exist in that case, which not being common to it with any large and strongly-marked cla.s.s of cases, have not fallen under the cognizance of the science. These circ.u.mstances 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 circ.u.mstances of the particular case are known to us sufficiently in detail, and that our attention is not unduly diverted from any of them.
This const.i.tutes 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 const.i.tutes any deviation from the _a 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-a.s.signable 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 _a 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 circ.u.mstances 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 circ.u.mstances, and so adding _pro hac vice_ a supplementary chapter or appendix, or at least a supplementary theorem, to the abstract science.
Having now shown that the method _a 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 _a 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 a.s.sured _a priori_ that we have taken into account all the material circ.u.mstances.
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 circ.u.mstances 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 circ.u.mstances 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 circ.u.mstances 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 circ.u.mstances 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 pa.s.s 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 antic.i.p.ations and the actual fact is often the only circ.u.mstance 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 circ.u.mstances by which the result is really determined. Such oversights are committed by very good reasoners, and even by a still rarer cla.s.s, 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 cla.s.ses of cases, and which belong to all place and all time; while it often happens that circ.u.mstances 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 _a 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 circ.u.mstances, 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 lat.i.tude 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 circ.u.mstances.
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.
Such, then, are the respective offices and uses of the _a priori_ and the _a posteriori_ methods--the method of abstract science, and that of specific experiment--as well in Political Economy, as in all the other branches of social philosophy. Truth compels us to express our conviction that whether among those who have written on, these subjects, or among those for whose use they wrote, few can be pointed out who have allowed to each of these methods its just value, and systematically kept each to its proper objects and functions. One of the peculiarities of modern times, the separation of theory from practice--of the studies of the closet, from the outward business of the world--has given a wrong bias to the ideas and feelings both of the student and of the man of business. Each undervalues that part of the materials of thought with which he is not familiar. The one despises all comprehensive views, the other neglects details. The one draws his notion of the universe from the few objects with which his course of life has happened to render him familiar; the other having got demonstration on his side, and forgetting that it is only a demonstration _nisi_--a proof at all times liable to be set aside by the addition of a single new fact to the hypothesis --denies, instead of examining and sifting, the allegations which are opposed to him. For this he has considerable excuse in the worthlessness of the testimony on which the facts brought forward to invalidate the conclusions of theory usually rest. In these complex matters, men see with their preconceived opinions, not with their eyes: an interested or a pa.s.sionate man"s statistics are of little worth; and a year seldom pa.s.ses without examples of the astounding falsehoods which large bodies of respectable men will back each other in publishing to the world as facts within their personal knowledge. It is not because a thing is _a.s.serted_ to be true, but because in its nature it _may_ be true, that a sincere and patient inquirer will feel himself called upon to investigate it. He will use the a.s.sertions of opponents not as evidence, but indications leading to evidence; suggestions of the most proper course for his own inquiries.
But while the philosopher and the practical man bandy half-truths with one another, we may seek far without finding one who, placed on a higher eminence of thought, comprehends as a whole what they see only in separate parts; who can make the antic.i.p.ations of the philosopher guide the observation of the practical man, and the specific experience of the practical man warn the philosopher where something is to be added to his theory.
The most memorable example in modern times of a man who united the spirit of philosophy with the pursuits of active life, and kept wholly clear from the partialities and prejudices both of the student and of the practical statesman, was Turgot; the wonder not only of his age, but of history, for his astonishing combination of the most opposite, and, judging from common experience, almost incompatible excellences.
Though it is impossible to furnish any test by which a speculative thinker, either in Political Economy or in any other branch of social philosophy, may know that he is competent to judge of the application of his principles to the existing condition of his own or any other country, indications may be suggested by the absence of which he may well and surely know that he is not competent. His knowledge must at least enable him to explain and account for what _is_, or he is an insufficient judge of what ought to be. If a political economist, for instance, finds himself puzzled by any recent or present commercial phenomena; if there is any mystery to him in the late or present state of the productive industry of the country, which his knowledge of principle does not enable him to unriddle; he may be sure that something is wanting to render his system of opinions a safe guide in existing circ.u.mstances.
Either some of the facts which influence the situation of the country and the course of events are not known to him; or, knowing them, he knows not what ought to be their effects. In the latter case his system is imperfect even as an abstract system; it does not enable him to trace correctly all the consequences even of a.s.sumed premises. Though he succeed in throwing doubts upon the reality of some of the phenomena which he is required to explain, his task is not yet completed; even then he is called upon to show how the belief, which he deems unfounded, arose; and what is the real nature of the appearances which gave a colour of probability to allegations which examination proves to be untrue.
When the speculative politician has gone through this labour--has gone through it conscientiously, not with the desire of finding his system complete, but of making it so--he may deem himself qualified to apply his principles to the guidance of practice: but he must still continue to exercise the same discipline upon every new combination of facts as it arises; he must make a large allowance for the disturbing influence of unforeseen causes, and must carefully watch the result of every experiment, in order that any residuum of facts which his principles did not lead him to expect, and do not enable him to explain, may become the subject of a fresh a.n.a.lysis, and furnish the occasion for a consequent enlargement or correction of his general views.
The method of the practical philosopher consists, therefore, of two processes; the one a.n.a.lytical, the other synthetical. He must _a.n.a.lyze_ the existing state of society into its elements, not dropping and losing any of them by the way. After referring to the experience of individual man to learn the _law_ of each of these elements, that is, to learn what are its natural effects, and how much of the effect follows from so much of the cause when not counteracted by any other cause, there remains an operation of _synthesis_; to put all these effects together, and, from what they are separately, to collect what would be the effect of all the causes acting at once. If these various operations could be correctly performed, the result would be prophecy; but, as they can be performed only with a certain approximation to correctness, mankind can never predict with absolute certainty, but only with a less or greater degree of probability; according as they are better or worse apprised what the causes are,--have learnt with more or less accuracy from experience the law to which each of those causes, when acting separately, conforms, --and have summed up the aggregate effect more or less carefully.
With all the precautions which have been indicated there will still be some danger of falling into partial views; but we shall at least have taken the best securities against it. All that we can do more, is to endeavour to be impartial critics of our own theories, and to free ourselves, as far as we are able, from that reluctance from which few inquirers are altogether him to expect, and do not enable him to explain, may become the subject of a fresh a.n.a.lysis, and furnish the occasion for a consequent enlargement or correction of his general views.
The method of the practical philosopher consists, therefore, of two processes; the one a.n.a.lytical, the other synthetical. He must _a.n.a.lyze_ the existing state of society into its elements, not dropping and losing any of them by the way. After referring to the experience of individual man to learn the _law_ of each of these elements, that is, to learn what are its natural effects, and how much of the effect follows from so much of the cause when not counteracted by any other cause, there remains an operation of _synthesis_; to put all these effects together, and, from what they are separately, to collect what would be the effect of all the causes acting at once. If these various operations could be correctly performed, the result would be prophecy; but, as they can be performed only with a certain approximation to correctness, mankind can never predict with absolute certainty, but only with a less or greater degree of probability; according as they are better or worse apprised what the causes are,--have learnt with more or less accuracy from experience the law to which each of those causes, when acting separately, conforms,--and have summed up the aggregate effect more or less carefully.
With all the precautions which have been indicated there will still be some danger of falling into partial views; but we shall at least have taken the best securities against it. All that we can do more, is to endeavour to be impartial critics of our own theories, and to free ourselves, as far as we are able, from that reluctance from which few inquirers are altogether exempt, to admit the reality or relevancy of any facts which they have not previously either taken into, or left a place open for in, their systems.
If indeed every phenomenon was generally the effect of no more than one cause, a knowledge of the law of that cause would, unless there was a logical error in our reasoning, enable us confidently to predict all the circ.u.mstances of the phenomenon. We might then, if we had carefully examined our premises and our reasoning, and found no flaw, venture to disbelieve the testimony which might be brought to show that matters had turned out differently from what we should have predicted. If the causes of erroneous conclusions were always patent on the face of the reasonings which lead to them, the human understanding would be a far more trustworthy instrument than it is. But the narrowest examination of the process itself will help us little towards discovering that we have omitted part of the premises which we ought to have taken into our reasoning. Effects are commonly determined by a _concurrence_ of causes.
If we have overlooked any one cause, we may reason justly from all the others, and only be the further wrong. Our premises will be true, and our reasoning correct, and yet the result of no value in the particular case. There is, therefore, almost always room for a modest doubt as to our practical conclusions. Against false premises and unsound reasoning, a good mental discipline may effectually secure us; but against the danger of _overlooking_ something, neither strength of understanding nor intellectual cultivation can be more than a very imperfect protection.
A person may be warranted in feeling confident, that whatever he has carefully contemplated with his mind"s eye he has seen correctly; but no one can be sure that there is not something in existence which he has not seen at all. He can do no more than satisfy himself that he has seen all that is visible to any other persons who have concerned themselves with the subject. For this purpose he must endeavour to place himself at their point of view, and strive earnestly to see the object as they see it; nor give up the attempt until he has either added the appearance which is floating before them to his own stock of realities, or made out clearly that it is an optical deception.
The principles which we have now stated are by no means alien to common apprehension: they are not absolutely hidden, perhaps, from any one, but are commonly seen through a mist. We might have presented the latter part of them in a phraseology in which they would have seemed the most familiar of truisms: we might have cautioned inquirers against too extensive _generalization_, and reminded them that there are _exceptions_ to all rules. Such is the current language of those who distrust comprehensive thinking, without having any clear notion why or where it ought to be distrusted. We have avoided the use of these expressions purposely, because we deem them superficial and inaccurate. The error, when there is error, does _not_ arise from generalizing too extensively; that is, from including too wide a range of particular cases in a single proposition. Doubtless, a man often a.s.serts of an entire cla.s.s what is only true of a part of it; but his error generally consists not in making too wide an a.s.sertion, but in making the wrong _kind_ of a.s.sertion: he predicated an actual result, when he should only have predicated a _tendency_ to that result--a power acting with a certain intensity in that direction. With regard to _exceptions_; in any tolerably ably advanced science there is properly no such thing as an exception. What is thought to be an exception to a principle is always some other and distinct principle cutting into the former: some other force which impinges against the first force, and deflects it from its direction. There are not a _law_ and an _exception_ to that law--the law acting in ninety-nine cases, and the exception in one. There are two laws, each possibly acting in the whole hundred cases, and bringing about a common effect by their conjunct operation. If the force which, being the less conspicuous of the two, is called the disturbing force, prevails sufficiently over the other force in some one case, to const.i.tute that case what is commonly called an exception, the same disturbing force probably acts as a modifying cause in many other cases which no one will call exceptions.
Thus if it were stated to be a law of nature, that all heavy bodies fall to the ground, it would probably be said that the resistance of the atmosphere, which prevents a balloon from falling, const.i.tutes the balloon an exception to that pretended law of nature. But the real law is, that all heavy bodies _tend_ to fall; and to this there is no exception, not even the sun and moon; for even they, as every astronomer knows, tend towards the earth, with a force exactly equal to that with which the earth tends towards them. The resistance of the atmosphere might, in the particular case of the balloon, from a misapprehension of what the law of gravitation is, be said to _prevail_ over the law; but its disturbing effect is quite as real in every other case, since though it does not prevent, it r.e.t.a.r.ds the fall of all bodies whatever. The rule, and the so-called exception, do not divide the cases between them; each of them is a comprehensive rule extending to all cases. To call one of these concurrent principles an exception to the other, is superficial, and contrary to the correct principles of nomenclature and arrangement. An effect of precisely the same kind, and arising from the same cause, ought not to be placed in two different categories, merely as there does or does not exist another cause preponderating over it.
It is only in art, as distinguished from science, that we can with propriety speak of exceptions. Art, the immediate end of which is practice, has nothing to do with causes, except as the means of bringing about effects. However heterogeneous the causes, it carries the effects of them all into one single reckoning, and according as the sum-total is _plus_ or _minus_, according as it falls above or below a certain line, Art says, Do this, or Abstain from doing it. The exception does not run by insensible degrees into the rule, like what are called exceptions in science. In a question of practice it frequently happens that a certain thing is either fit to be done, or fit to be altogether abstained from, there being no medium. If, in the majority of cases, it is fit to be done, that is made the rule. When a case subsequently occurs in which the thing ought not to be done, an entirely new leaf is turned over; the rule is now done with, and dismissed: a new train of ideas is introduced, between which and those involved in the rule there is a broad line of demarcation; as broad and _tranchant_ as the difference between Ay and No. Very possibly, between the last case which comes within the rule and the first of the exception, there is only the difference of a shade: but that shade probably makes the whole interval between acting in one way and in a totally different one. We may, therefore, in talking of art, un.o.bjectionably speak of the _rule_ and the _exception_; meaning by the rule, the cases in which there exists a preponderance, however slight, of inducements for acting in a particular way; and by the exception, the cases in which the preponderance is on the contrary side.
THE END.
NOTES:
[8] We say, the _production_ and _distribution_, not, as is usual with writers on this science, the production, distribution, and _consumption_.
For we contend that Political Economy, as conceived by those very writers, has nothing to do with the consumption of wealth, further than as the consideration of it is inseparable from that of production, or from that of distribution. We know not of any _laws_ of the _consumption_ of wealth as the subject of a distinct science: they can be no other than the laws of human enjoyment. Political economists have never treated of consumption on its own account, but always for the purpose of the inquiry in what manner different kinds of consumption affect the production and distribution of wealth. Under the head of Consumption, in professed treatises on the science, the following are the subjects treated of: 1st, The distinction between _productive_ and _unproductive_ consumption; 2nd, The inquiry whether it is possible for _too much_ wealth to be _produced_, and for too great a portion of what has been produced to be applied to the purpose of further _production_; 3rd, The theory of taxation, that is to say, the following two questions--by whom each particular tax is paid (a question of _distribution_), and in what manner particular taxes affect _production_.
[9] The physical laws of the production of useful objects are all equally presupposed by the science of Political Economy: most of them, however, it presupposes in the gross, seeming to say nothing about them.
A few (such, for instance, as the decreasing ratio in which the produce of the soil is increased by an increased application of labour) it is obliged particularly to specify, and thus seems to borrow those truths from the physical sciences to which they properly belong, and include them among its own.
[10] The _science_ of legislation is an incorrect and misleading expression. Legislation is _making laws_. We do not talk of the _science_ of _making_ anything. Even the _science of government_ would be an objectionable expression, were it not that _government_ is often loosely taken to signify, not the act of governing, but the state or condition of _being governed_, or of living under a government. A preferable expression would be, the science of _political society_; a princ.i.p.al branch of the more extensive science of society, characterized in the text.
[11] One of the strongest reasons for drawing the line of separation clearly and broadly between science and art is the following:--That the principle of cla.s.sification in science most conveniently follows the cla.s.sification of _causes_, while arts must necessarily be cla.s.sified according to the cla.s.sification of the _effects_, the production of which is their appropriate end. Now an effect, whether in physics or morals, commonly depends upon a concurrence of causes, and it frequently happens that several of these causes belong to different sciences. Thus in the construction of engines upon the principles of the science of _mechanics_, it is necessary to bear in mind the _chemical_ properties of the material, such as its liability to oxydize; its electrical and magnetic properties, and so forth. From this it follows that although the necessary foundation of all art is science, that is, the knowledge of the properties or laws of the objects upon which, and with which, the art dons its work; it is not equally true that every art corresponds to one particular science. Each art presupposes, not one science, but science in general; or, at least, many distinct sciences.