At the beginning of Book IV Aristotle’s discussion takes a more practical turn. The political theorist, he maintains, must investigate four kinds of constitutions:
1. The ideal or absolutely best conceivable, without regard to actual circumstances.
2. The best attainable in the circumstances that prevail.
3. Constitutions inferior to 1 and 2, which evidently may be worth putting into practice and preserving.
4. An all-purpose constitution which would suit all states. He must also appreciate that there are several different kinds of each of the main constitutions (that there are, e.g., several different varieties of democracy), and that each variety requires different laws. This programme of study is embarked upon in chapter iii.
To attain (1) and (2) would be the concern of a ‘utopian’ political theorist such as Plato: the Republic presumably describes, in his view, the first kind of constitution, the Laws the second (but note the wider horizons of Laws 739ab ff.). Aristotle, however, evinces a certain impatience with utopianism: he is prepared to offer help to constitutions far removed from the ideal – and, interestingly enough, not by sudden or radical constitutional change, nor by demanding a fresh start, but by ‘Fabian’ gradualism and piecemeal ‘social engineering’, and with the consent of the inhabitants of the state concerned. The whole chapter is a salutary reminder that in spite of all Aristotle’s theoretical discussion, and his keen interest in the utopias he describes in Book II, his Politics has an essentially practical purpose.
1288b10 In all the skills and sciences which do not operate piecemeal but give complete coverage to some class of objects, it is the task of a single skill or science to investigate what suits each individual class. For instance, what kind of training is advantageous for what kind of body, and what training is best? For the best must necessarily suit the body which is best endowed and best equipped. It is a further task of gymnastic to investigate what single form of training for everyone will serve the greatest number. And even if a man has no ambition to acquire the condition or the knowledge1 appropriate for athletic contests, it is none the less the business of the teacher or gymnastic trainer to impart that2 degree of ability too. We see the same principle at work in medicine, shipbuilding, clothing and every other skill.
1288b21 So it is clearly true also that it is the task of one and the same science to consider the best constitution, what it is and what it would be like if it were constructed exactly as one would wish, without any hindrance from outside. Another of its tasks is to consider what constitution is suited to what persons, because for many the best is perhaps impossible to attain; so the good lawgiver and the genuine statesman will have to bear in mind both the ‘absolutely best’ constitution and the ‘best in the circumstances’. There is also a third, which starts from an assumption – I mean he must be able to consider also a constitution which is given, both how it could come into being, and how once in being it may last longest. I am speaking particularly of a state which happens to operate neither the best constitution (being without provision even for its basic needs), nor the one possible in the actual circumstances, but a worse. Besides these there is a fourth he must recognize – the constitution which will suit pretty well all states. This is why the majority of those who give their views on constitutions, however well they may do it in other respects, fall down on questions of utility. For we must consider not only the best constitution but also the possible, and likewise also that which is easier and more within the reach of all states.
1288b39 But there are of course some today who concentrate on the search for the highest constitution, which needs ample resources; others talk rather about some common3 constitution, yet dismiss entirely the constitutions that actually exist and simply give their approval to the Lacedaemonian or some other. But what is needed is the introduction of a system which the people involved will be easily persuaded to accept, and will easily be able to bring in, starting from the system they actually have. Hence it is a no less difficult task to put a constitution back on its feet than to create one from the start, just as relearning a lesson is no less hard than learning it in the first place. Thus it is another of the duties of a statesman, in addition to those stated, to be able to render assistance to actually existing constitutions, as noted before.4 But he cannot do this without knowing how many forms of constitution there are Some people think that there is only one democracy and only one oligarchy. This is not true, and therefore one should not forget how many differences there are between constitutions and how many different ways there are of combining them.
1289a11 This same practical wisdom enables one to discern both which laws are best, and which of them suit each constitution. For one ought to lay down laws to fit constitutions (as indeed is always done), not constitutions to fit laws. A constitution is the arrangement which a state adopts for the distribution of offices, and for the determination of sovereignty in the constitution and of the end which the particular association aims at realizing. Laws distinguishable from descriptions of constitutions are those according to which the rulers shall rule and shall watch out for those that transgress them. This makes it quite clear that even for the purpose of laving down laws it is necessary to start with a grasp of the varieties of constitutions and the definition of each, because it is impossible for the same laws to be good for all oligarchies and all democracies, since there is more than one form of each, both of oligarchy and of democracy.