The Question: How can I tell what is just and what is unjust? Presumes the higher: from whence comes the just and the unjust, what causes these differences, what is the source of all “thou shalt”? The answer to the latter question is therefore the decisive one for any ethics. The philosophy that only recognizes what follows from reason can therefore also look nowhere for this source of the ethos than in reason. In this consists natural law.
The conception of the origin of the ethos
The Platonic Idea of the Good, through which what corresponds with it is good, that which conflicts with it is evil, is a source of ethos apart from reason. It has an original independent existence. And Plato could not even raise the question, why is the good good, and what is that anyway? The newer ethics, on the other hand, is based on this question: what does it mean, I shall, is it something good or bad? I can deny all of that, even cancel these ideas and still exist and think without contradiction. I will only consider the “I shall,” the “good and evil” to be something, if apart from them my thinking itself would cease to exist. The good must therefore be logically deduced and must be defined, that is, it must be composed from pure thought-determinations and can be decomposed again into it. With Kant, for example, only the form of all thought itself (necessity and universality); with Hegel, likewise a product which the empty thought determination of being and the law of thought (dialectic) together bring about without any other ingredient.
History of the conception of the origin of the ethos
The Christian world recognized a cause of ethos independent of reason before it philosophized: in the will of God and in the content thereof, the divine holiness, which is of specific determinacy, positive, susceptible to and in need of no further (logical) deduction. To remove this cause was therefore the precondition, the first step that natural law had to make to clear space for itself. The beginnings of this were already given in the philosophy of the Middle Ages: in the lex aeterna, which the scholastics set over God, in holy nature which is in Him prior to any decisions, from which they believed they needed to derive the ethos (convenientia cum sanctitate divina antecedenter ad voluntatem divinam). By this, freedom of decision and fixation in God was abolished, and it was only required to explain reason as this: that which by necessity is determinative of Him and the world. This occurred by the assertion that the differences of right and wrong would stand according to reason, even if there were no God. Because then God cannot possibly be the cause of them, neither His sanctitas nor His voluntas – otherwise without Him the effects would lapse as well – but only reason. This assertion, which was adopted by the founder of natural law, Grotius, (although he by no means was its author), was taken under his wing by Leibniz against adversaries, and emphatically pronounced: as the laws of geometry would have to be found necessary even if one denied God, so also the laws of justice. And the deviating regulations which according to the Bible (which Leibniz acknowledged) God issued at various times, form no hindrance to this, because these exemptions are no less necessary consequences of reason than the rule; God Himself is only praised because He is righteous, and acts ut omni satisfaciat sapienti.
Wolff sets the law the source of which is the will of God, as positive over against the lex naturalis which has a ratio sufficiens in the nature of man, a classification that can still be found in most textbooks of standing law. As can be seen, it is not the intention here that, as was indicated, good and evil exist by themselves (perseitas honestatis et turpitudinis); but that good and evil are such by the laws of thought. This view was indeed contradicted by prominent natural law teachers. Following Pufendorf, there is no good and evil without the impositio of a suzerain, and this is God; man did not even have the socialis and rationalis natura in a manner ex immutabili quadam necessitate but rather ex beneplacito Divino. Thomasius protested against the distinctions of the scholastics – comparing their lex aeterna with the matter of pagan philosophers – and also against this assertion of Grotius, and declares that his principle of reason should be the benchmark (principium cognoscendi), but by no means the cause of the ethos (principium obligationis). But all of this only exists in words, without application and consequence. The treatment proceeds in such a manner as if everywhere the opposite view were accepted. And this could not be otherwise, if reason is to be the standard of the just, regarding which no doubt prevails amongst the collective caretakers of this doctrine. For now, what is just is what it contains in itself, not what a cause outside of itself requires, and the effect as from itself regardless of what it sees [unabhängig sie anschaute]. It is not merely the eye, but light and color themselves. What reason is, could not suffice to find the differences between right and wrong, if there were anything else outside it which caused the differences. The assertion that God is the cause of the ethos is therefore canceled by the other: reason is the (positive) standard thereof. Certainly an association could lie in God having given us reason, and that therefore He wills what follows from it. But in that case, did God only create the pure determinations of thought and the concept of our nature, stripped of any specific life, and not our specific moral quality [Bestimmtheit]? Should what unfolds in history, which He in fact likewise directs, not be quite as validated? And how can we arbitrarily attribute to Him that He wishes to allow the urge to morality produce its requirements in no other way than the results of logic, given that the one produces deeds, the other simply takes up and holds fast to objects? Therefore, it is not just individual statements by which Pufendorf, Thomasius and those professing to follow them, come into conflict with themselves. So Pufendorf requires that every suzerain, from whom all obligations proceed, not only has the power but also justus causas et rationes. The impositio as final cause of obligation thus itself has a higher cause of obligation over it, rational laws, a contradiction that Leibniz rebukes. So Thomasius praises the benefits of natural law in order to have a law common with pagans and atheists. The ratio “etsi daretur Deum non esse” therefore also has force with him.
– But not just that; its systems as a whole are driven by the rationalist principle. In practice they everywhere bind the will of God, which they make into the cause of the ethos, by reason. He shall not be subject to the lex aeterna and his own sanctitas. But, it prescribes to Him that what follows from the urge to sociability etc., and this alone is what He shall will, while He shall not will other things outside this. Therefore, with them as well as with their opponents, He plays no other role than a Deus ex machina. He has to pick up everything that reason can no longer achieve. He must invest moral duty with its real power over people, institute entitlement, and be the cause of such obligations for which one can provide no ratio, for example, the prohibition of incest. With such treatment, controversy is really quite vain; though initially the subject of the most careful debate, during the course of that debate it also becomes increasingly drab, while God increasingly disappears, until finally Kant expressly declares reason to be the cause of the ethos. Since him, the relation of God to duty is no longer discussed, and it may well be surprising to see that controversy once again prompted here with importance. –
Thus, from the start of abstract philosophy, the opposite mode of conception is everywhere connected with it. But already here, the effectuating element in the scientific treatment is reason alone. There only need be unequivocal communication to banish entirely even the appearance of that conflicting element. –
Reason, which the ethos is to follow, now however requires a basic concept from which it is inferred, which, as goes without saying, must still remain after all abstraction. According to the subjective-rationalistic standpoint of natural law, this concept is the existence of the thinker, human nature. In reality, this nature is always something determinate, determined by individuality, environment, fate, time, matter, in short, by history. But in such a determinacy, it has no logical necessity. Inseparable from the concept of man are solely the characteristics of sensibility and thought. A man without moral feeling, even if he has never yet existed, is at least still conceivable; but a man without physical existence or without the capacity for thinking would be a logical contradiction. The sensorial-rational (i.e., thus thinking) nature of man is therefore the basic concept of abstract ethics. It is then actually premised by all natural law preceptors. But initially one did not know how to make any immediate use of it, and by necessity set up the system itself on any instinct of the human being, that one hoped to attain in deduction, for example, the instinct to sociability. The presumed concept of thinking nature was only utilized in order to justify as law, the rational inference from the instinct. What must here attract attention is that any system of natural law is built exclusively on such a instinct and does not make the attempt to derive it from all the instincts of human nature. This has to do with the abstract treatment. The manifold instincts and feelings are really connected in our nature; but they have no logical unity, no concept that is common to all, yet individually in each. But rationalism urges just such a simple principle. It contradicts as a principle the living fullness, but no less also the merely composite. Hence, as long as there is life force in it, syncretistic process does not arise, but only at the time of its exhaustion, where the original confidence to achieve simplicity is abandoned. To take an isolated instinct as ground, therefore lay of necessity in the character of the natural law; what was arbitrary was whether this one or that. Therefore exchange took place between all possible kinds, sociability, fear, happiness, perfection, etc. In this manner, the list of human instincts was run through, and the natural law schools follow this thread. The development took no rest until at length Kant secured that basic concept and summed it up in its complete abstraction: thinking nature as mere consequence; the sensorial as the restriction contained in any of its manifestations, of that pure consequence. From now on, the concept of a being that thinks but is limited by sensoriality (finite) is the principle. Only this has a logical necessitation, it is the last remnant that is left standing after abstracting from the existence of man. And from the concept of thinking nature, it is also only possible to infer – as required – by mere reason. Any other instinct than that of consistency itself, for example for happiness, acts outwardly and is energized from the outside. In order to say what it requires, both the consequence of action in the world and the repercussions of the external object on one’s own condition must be observed.
This provides the concept from which nothing more can be abstracted (the necessary beginning) and from which now the entirety of ethics must arise, merely from logical reasoning; as Wolff previously expressed it: “Principium ex quo continuo ratiocinationis filo deducuntur omnia” [[The beginning of the continuous thread of reasoning can be deduced from it].
History of the basic concept
In the series of ethical systems, Hobbes is customarily the one picked out as opposing rather than promoting the development of natural law. But certainly unjustly. It in no way differs from the others, since he elevates the instinct of fear from human nature, instead of some other instinct, and deduces his results from this, to which he certainly has the same right. It follows from the conception of a fearing being that protection is sought for life and limbs – “pax quaerenda.” It does not follow from it that contracts are kept outside of the state; for this compliance indeed provides no certainty that does not likewise infringe the other. Therefore, for Hobbes the state of nature is without rights, and one takes offense at this. But it follows from the instinct of fear that one produce a civil condition in which the supreme rule must be “pacta servanda.” Therefore, Gros unjustly accuses him of confusing what people do with what they should do. This is because to Hobbes that utter arbitrariness is really nothing more than the minor premise, while he already has the major premise, which is what they should do: “protect themselves” – as elsewhere: “please themselves” – from which the state follows as conclusion. Equally unfounded is Thomasius’s objection that the pacta presuppose a law. This law dictates human nature as fear. Even Hobbes is not empirical. If he was, he would have made the multiplicity of instincts in human nature, which experience demonstrates, into the principle. Because he is not empirical but abstract, and only for that reason chooses the one of fear only, and has everything emerge from it, as reason would have it, “necessitate quadam non minore, quam qua fertur lapis deorsum” [a kind of necessity, not less than what is said of a stone downwards]. So in every respect he belongs to the natural law development – he stands or falls on its foundations and is far from opposing it – is only a variation on the theme – consistent with the others in principles, requirements, and procedures – only distinguished from them by an entirely incidental assumption. –
Abstraction from relations
Turning now to the individual ethical requirements as conscience makes each known, their diversity is linked to the diversity of circumstances in which one operates. In industry one feels obligated to diligence, in trade to honesty, in social interaction to benevolence; a particular course of action is called for by the family, a particular one for the state. So it would be natural to seek the reason for the difference in these circumstances. To this end it would not suffice to be regarded merely as a different material, but as another source. Each must be conceded a peculiar moral objective that has its origin in itself; but then the unity for these various objectives would have to be sought outside man. Therefore rational philosophy immediately annihilates these relationships, in order to recognize them again only if they contain its fundamental concept of ethics. This abstraction stands in relation to the condition of the state of nature. It has been set up in different ways, as a historical fact, as a presumption, fiction, finally, understanding itself, as a scientifically necessary abstraction. The impulse to its adoption is the same in all these ways: I can imagine myself without the state, it is therefore not a priori required by reason; I must now assume that the state was not in existence, in order to see whether my concept as a thinking being leads me back to it. In the same way one can oppose the state of nature to the condition of the family, to that of social interaction (mutual contact), and has also done so, even when not done expressly. For the fact that, for example, the need and the objective of agriculture regarding a complex of estates or the dissolution thereof should decide nothing, the freedom of the individual everything, presupposes that instead of the actual relations of agriculture, one takes the abstraction thereof, the state of nature, as starting point. –
Consequences of this abstraction
Since the real existence of these conditions is given up, their real requirements are also, and they can only apply, and to that degree apply, if that inference yields them. Thus, the shapes of the moral world no longer impose laws on people, they rather receive them first from the concept of their existence, and therefore of necessity are entirely different than what is required by the moral world’s own nature.
Namely, when man conceives himself released from any association and still perceives a rule over himself, this rule can only be enacted for him as an isolated case, he is its exclusive subject. Only what he is capable of, only what still makes sense, when one looks separately at his action and fulfillment, is his goal. And it must be satisfied by him: when it is fulfilled, when no blame for it attaches to him. A general condition the achievement of which also depends on the participation of others, cannot be demanded of him, thus cannot be the object of the rule. Thus, for example it can only command: “Thou shalt be prepared for the state!” not: “The state shall exist!” Otherwise he would not be summoned as an individual but as part of a totality. The Greek ethos is directed to an order of the world. It is to be established to satisfy that, without considering how people’s actions are constituted. Here, however, the quality of this action is what is required. The result, and what is constructed by the same in the world, is only additional and not what is originally willed. Nearly all of the earlier systems of natural law begin with the concepts of action, its kinds, its attribution, etc. Hence with the Greeks, the duty of the citizen is discovered from the ethos of the state; but with the modern versions, the duty of the state is imagined from the duty of man without the state. This has supreme influence on the content of the ethos. Because with the former, requirements must arise for man which could never be made for him if one thinks of him individually. With the latter, however, the state itself is robbed of its peculiar duties because the individual cannot or may not meet them. The meaning of punishment, for example, cannot be retribution; because which people are entitled to administer justice? That it therefore likewise does not accrue to the state, is then self-evident. The existence of social ranks [Ständen] must be abandoned as an ethical requirement prior to any investigation, because it is not a matter of my action. If every rank, solely pursuing its orientation, in this achieves the pinnacle, but not without the hardness of one-sidedness – when the warrior is brave but brutish, the priest pious but shiftless, the scholar highly educated but effeminate – then this view would rightly deprecate the imperfection of men in such conditions; but it would not notice that which also is yet admirable in the same, the fullness and power of the whole. Therefore, the content of ethics in its entirety consists merely in commands over the isolated actions of individuals.
Content of the ethos
What these acts might be, should indeed, according to the requirement, arise from the basic concepts. But since, as will be demonstrated in the issue, such an abstraction is not sufficient for positive results, the interest of the entire orientation is herein also immediately operative. Thus, the goal of the commanded actions – is only humans. Either rationally to strive for his own satisfaction – as Hobbes, Thomasius – or, since virtue has devotion in it, to strive for the satisfaction of other people, their welfare, their freedom, etc. Apart from the beings who resemble him, his abstracting reason and his interest offer him no object. Unity, the development of the strength of the state, the symmetry and beauty of life, faith, devotion, honor recede into the background or disappear entirely. They do not provide well-being to the individual. Kant consequently removed the duties towards God from ethics. The ancients and many of the moderns maintain them. The obligations towards Him, who in terms of His concept is the absolute cause of all being and obligation, thus obtain their sanction by a second absolute, the nature of man, and appear alongside other obligations, although they, if they exist, are only those that this makes into obligations. This is no different than when a Kantian wishes to treat the duties toward the moral imperative itself among those toward one’s neighbor, parents, children, and spouses. – –
Now reason still finds a goal outside human existence by abstraction, and it is itself, the form of thinking. To satisfy this in action is its own fulfillment. It is conceived partly as a second task in addition to the satisfaction of other people, partly as the epitome and ground of all other tasks. But its concept is none other than the uniformity of action according to principles, regularity, immutability, not being affected by changing emotions.
This negative virtue of never contradicting itself is found in Spinoza’s view of the rule of the soul over the emotions, in the pax interna of Thomasius, which consists in discouraging the passions, and at its most conscious, finally, with Kant in the supreme rule of ethics: act according to a law which is a universal law, through which a contradiction with itself cannot ever arise.
 For the development of abstract philosophy in general, and therefore for this entire approach, it is of the highest importance that reason be held in the truly intended sense of pure thought, and not have attributed to it any specific content (e.g., a design [Absicht] or attribute of God supplied up-front), which of course solves many problems, but also abandons the basic requirement, which is to accept nothing without logical necessity. Now the threat of such tacit assumption is greatest in ethics. For a long-standing custom that leaves no room for doubt, of deriving morality from reason, has lent to these words the signification of morality; and in none of them does morality not resonate in its tone, making one perhaps wonder that the derivation of obligation from reason, which is precisely derivation from morality, can be doubted here. This is further supported by the current confusion of language in philosophy and the usage adopted by many since Jakobi, of conceiving reason to be the immediate perception of everything divine, holy, good, just, thus precisely the opposite of discursive reasoning [vermittelnden Denken].
The principle upon which natural law and the entirety of rational philosophy is based, is pure thought. It does not wish to proceed from morality and justice, but only to derive them from it. It is also recumbent, merely existing thought, that is, the epitome of the pure determinations and laws of what it is, not of what it produces through its activity.
What is proper to the rationalistic treatment can be explained from this, and apart from it could not arise. Reason in those other meanings would lead to a legal philosophy of an entirely different character. It is stated even with the teachers of early natural law that by reason they understand thinking, e.g. Pufendorf nat jus. l. 1, c. 1. §. 2. Thomas jurispr. divin. l. I, c. 1. §. 38, who refers to a statement of Descartes: homo dum intelligit, cogitat, dum vult cogitat, dum sentit cogitat. And though subsequently even important men, such as Leibniz, quite often attribute moral laws that are independent of thought, to thought, as contained in the ratio; though they occasionally understand active observation [Betrachtung] and not logical development as ratio; then this is merely a lack of consistently clear awareness in their work. There is since Kant, who highlighted precisely this clear awareness, no more of this wavering among rigorous philosophers, although now non-philosophical writers are using all the meanings of reason in order to make one among them into a principle, namely as argumentation on grounds [Raisonnement aus Grunden], like Weiland in the Wolffian school.
 Prolegomena, de jure belli et pacis, c. 11.
 Observationes de principio juris c. 13.
 Monita ad Puf. princ. c. 4.
 Instit. jur. nat. Pars I, c. 2. §. 39.
 Jus nat. et gent. l. I, c. 2. §. 6. de officio hom. et civis l. 1, c. 2. §. 2.
 Inst. juris pr. divin. l. I, c. 1. §. 31. Dissert. prooemialis §. 39.
 Fundam. jur. nat. l. I, c. 6.
 E.g., Wolff Pars I, c. 3. §. 43. loc. cit.
 De off. hom. et civ. l. I, c. 2. §. 5.
 Dissert. prooemial., at the end.
 Wolff loc. cit. lib. I, c. 2. §. 41.
 Thom. inst. juris pr. divin. l. I, c. 1. §. 84.
 Compare Gundling, Darjes, Nettelbladt, Höpfner, with earlier generations.
 Hoffbauer (Untersuchungen über die wichtigsten Gegenstände des Naturrechts [Studies regarding the main objects of natural law]), prompted by Kant, thought that he had to go farther. The abstractum of man is still too concrete for him, and so he arrives at the concept of a rational being, which is not like this, and therefore is not exactly human. The original and acquired rights that are derived from this concept of the rational being thus form the pure natural law, while those derived from the concept of man form the applied natural law.
 E.g., Fichte, Naturrecht, Part II, p. 129.