There is no more fitting image for the importance of reason in the Age of Enlightenment than that of the court of justice. Immanuel Kant used this image several times. He calls his Critique of Pure Reason "the true court of justice for all disputes". Enlightenment is expected from reason. However, it is "very inconsistent" to dictate to it what the outcome should be. The biggest and most important questions, whether there is freedom, God and a future life, can be disputed and clarified. This dispute has no end, because reason must constantly subject itself to criticism and recognise its limits in the process. It is the boundaries between concrete knowledge and speculation that must not be crossed in court.
Instead of knowing the right answers to those ultimate questions, we have to be content with the belief that freedom, God and immortality exist. The court is always in session and the results of the Enlightenment remain open and controversial. The alternative would be a "war", a natural, violent, bloody and deadly confrontation over claims to be enforced by some against others, as was and still is the case in many religious wars. Instead, everything should be negotiated calmly in an open process before the court of reason.
In the image proposed by Immanuel Kant, reason is the final authority in all negotiations. However, it must not decide dogmatically, but should critically examine which decision "free citizens" could agree with. Whatever claims to be valid must stand up to the self-critical demands of reason before the public forum. The consent of free citizens that Kant has in mind must not be confused with the consensus proposed by modern consensus theorists, because although the consensus should be rational and ethically demanding, it should also be valid and binding for all. The court would not be definitively closed, but reason would be self-confident rather than self-critical, autocratic and instructive rather than modest and reserved.
Kant's enlightening, self-critical reason is neither a consensus rationality nor the thinking capacity proposed by Descartes, which wants to recognise everything clearly and definitely. Few people have seen these differences more clearly than the British philosopher Onora O'Neill, who combines Kant's conception of the court and his idea of public debate to form a whole. In her view, the unifying element is the Categorical Imperative, which tests all maxims and rules, both personal and political and legal, to see whether they are contradictory and can really be wanted by everyone.
The self-commitment to act in such a way that the maxim can become a generally applicable law excludes coercion, fraud, enslavement, exploitation and any kind of instrumentalisation. Anyone and everyone who follows the maxims of unprejudiced self-thinking, thinking in the same place as everyone else and freedom from contradiction can reliably examine every conceivable maxim and then agree to a law that applies to everyone. To do this, however, everyone must have understood what is at stake. These are the maxims of the personal and public use of reason, which are intended to serve general enlightenment. They are primarily maxims of autonomy and only then maxims of reason. This, too, is a thought of Kant's that Onora O'Neill adopts as her own.
Conscience as a court of law
Kant uses the metaphor of the court not only for reason, but also for conscience, which he calls an "inner court in man". This is an individual court that does not meet in public and is not transparent, which has nothing in common with the court of reason and must not have anything in common either. The comparison is illuminating. Through his conscience, every defendant and judge is one person and this is not compatible with a court of law. For this reason, conscience must think of an "other (than man...)" as judge, an "ideal person... which reason creates for itself". And this "being having power over everything" is called "God". However, since God is an idea for Kant, and reason must not come into contradiction with itself, as we have just heard, the only thing that remains is belief in a supreme being, and the duties that are tested by the Categorical Imperative can be obeyed "as divine commandments". Ultimately, God exercises his powerful role within the framework of a metaphor. This will tend to disappoint those who believe in him, and those who do not believe in him will find the metaphor of the court altogether suspect.
The religion of reason that Kant proposes is a belief in the law, a belief in the moral law that rational beings impose on themselves in their autonomy. St Paul's insight that no one is justified by the law (Gal 2:16) was certainly not unknown to Kant, but he does not take it seriously as a statement of a historical religion. In his Critique of Judgement, he even proposes a moral proof of God. This consists of reason bowing before itself and pledging allegiance to its own commandments, in recognition of the divine character of reason itself, so to speak. Reason as God within us is honoured by ourselves. We look up to reason as an ultimate authority that is higher and greater than each and every one of us humans. The cause of enlightenment is not furthered by this exaltation of reason within us. If it were a game, it would have to be "everything back to square one".
Principles of reason
The comparison of the two court images points to a danger that threatens the court of reason when reason becomes uncritical. Faith in reason, with its moral and rational-religious flavour, exaggerates reason. Kant's faith in reason will not be discussed further here. Instead, it is now a matter of examining the extent to which what claims to be valid can stand up in the court of reason. How far does this image of reason stand up? What actually is reason?
We call 'reason' an activity of thinking, but not just any thinking, but thinking according to rules, according to standards that should themselves be reasonable. When we say that reasoning should be logical, we mean that the rules of reasoning are logically binding. In a process of justification, something reasonable, reliable and true can only emerge in the end if the justification uses the best possible, most reliable standards and logically transparently deduces from principles according to rules. As an intellectual activity, reason uses standards of all kinds, principles, rules and norms, but is not itself a principle, rule or norm.
This is important to know because the activity of reasoning and the instruments of this activity must be kept apart, otherwise the result of justification cannot be valid. It is not possible for reason to be the activity of thinking and at the same time its instrument and rule. The activity would always be in agreement with itself because - as Kant formulates it for conscience - it would be the accused and judge in one person. A controlled, verifiable activity is only possible if there is a difference between the activity of reason and its examination by rules.
The first important logician, Aristotle, showed with his syllogistic how reason should act in order to achieve valid results. The form of arguments and their application must be separated. What this means is shown by the example of the first syllogistic form of argument: if the upper proposition "all men are mortal" is valid and the lower proposition states "Socrates is a man", then the conclusion "Socrates is mortal" is also valid. The validity of the conclusion depends on the correct application of the rule of inference, but is not identical with this rule.
We are talking about inferring, deducing, deriving something from superordinate clauses, which we can also call 'principles'. Of course, the superordinate clauses and principles themselves must be valid. The most important principle for Aristotle was the principle of contradiction. One of the formulations says: "That ... the same thing in the same relation (...) cannot possibly occur and not occur at the same time" (Metaphysics, 1005b 19). The flower of a plant cannot simultaneously belong to the plant and not belong to it (my example). Aristotle calls this principle the most certain of all. It applies without restriction, but cannot be justified. Today we know a number of other formulations of this principle, e.g. that a sentence cannot be true and false at the same time. This makes sense, although there is no proof or justification for it. The principle of contradiction applies without deduction. Aristotle and many other philosophers discovered it, or rather found it to be correct and important. They did not invent it. Basically, all principles are valid without derivation. They are found at some point and found to be irrefutably correct and indispensable. Principles cannot be constructed because the construction would in turn presuppose principles that would in turn have to apply. This would lead to an endless regress of justifications.
Let us take as an example of a principle one that is perhaps more familiar to us than that of contradiction, the principle of human dignity. It can be found in the first sentence of the German Basic Law. It says: "Human dignity is inviolable." Because dignity is a principle, the second sentence states: "It is the duty of all state authority to respect and protect it." The principle of human dignity is also valid without justification, without deduction. Many theorists do not want to recognise this and try to justify it. This cannot succeed because any justification of a principle would in turn presuppose at least one other principle that would have to be used to prove its validity. Such a principle would also have to be valid and would have the same problem that it could only be justified with another principle.
Aristotle saw that reason not only derives knowledge from principles, but also proceeds inductively, relying on standards that actually have to be found and confirmed first. The mortality of man is not a principle, but an experiential certainty, in fact the only certainty we know that is independent of our thinking (in contrast to the Cartesian certainty of 'I think', which is a product of thinking).
Politics and jurisprudence also need standards that should originate from the real world, because they should also prove to be suitable there. What is just must be demonstrated in the real world and not in a theory. There is also not just one standard of justice, but at least two, one based on equality and one based on the merit that everyone earns for themselves. These two standards do not even have a common denominator. Depending on the political system, they apply until further notice, one in an egalitarian, the other in an elitist system. Nor do we have a principle for the best form of government. Although democracy aims to be the best form of government, it has very different manifestations with different electoral systems, divisions of power and supervisory bodies. Human dignity is a principle of our democracy. However, it is not a sufficient condition for a democratic order. Much more is needed for this.
For our question about reason as a court of validity, Aristotle's insight is important that whenever we want to prove that something is so and not otherwise, we always start with "original and undemonstratable things", i.e. with propositions for which there can be no proof because they are valid without derivation. This information seems indecisive and uncertain. Can Aristotle not offer us more certainty in the search for valid knowledge?
He visualises this search in such a way that the first step is to find the principles from which we can draw conclusions. They are the first - not justifiable - causes of 'scientific knowledge'. Of course, before we take the first step, we have previously learnt and acquired prior knowledge and sensory perception. Aristotle is a good observer. However, he is also aware that there are two types of prior knowledge, namely that which, like perception and what we have learnt, is more or less earlier in time and is closer or further away from us individually. And then there is also that which is "earlier per se" and furthest removed from experience, the principles from which we draw conclusions. In the order of knowledge, the former is the concrete individual, the latter the most general, the earliest. The most general, the earliest are principles of our thinking. They apply "unmediated", without further preconditions, without derivation.
Truth and validity
Aristotle did not recognise the image of reason as a court of law. He would also reject this image because he was a good observer and knew that knowledge cannot be a product of self-regarding, omnipotent reason, but is based on experience, on perception and observation of what happens in nature. He is convinced that what can be justified as valid establishes a connection between what actually exists and what we can judge with the means of our rational thinking and judgement. This can be something general, such as regularities in nature, for the cognition of which the image of the court of reason is appropriate to begin with. It can also be something special that manifests itself in this way and no other, but cannot be generalised. I call this 'exemplary validity'.
Before I say more about this kind of validity, I want to address the very obvious question of whether truth is not the best measure of what is or should be true. What is more plausible than the assumption that what is true should also be valid? Truth and validity are indeed connected, but how? It would be wrong to believe that truth could be a measure of what is valid. On the contrary, truth itself is the result of a proof of validity.
The best witness to the goal of proving the validity of propositions is Gottlob Frege. His aim is to recognise scientific truth on the basis of logical laws. He developed laws of thought based on arithmetic. He wanted to find out "what the justification of truth is based on at its deepest level". Strict, complete proofs on the basis of "primal truths" and "primal laws" should ensure the validity of the truth of propositions. These premises are not a product of logic. They must be assumed, presupposed, discovered. Truth is then the goal and not the starting point of the proof of validity.
Frege designed the modern, mathematics-orientated, formal logic, which bears little resemblance to Aristotle's syllogistic logic. Nevertheless, both have one thing in common. Both are based on principles that are not part of logic itself, but rather are superior to it. They are valid without derivation, in principle. This means that Frege's proof of the validity of scientific truths also has non-derived foundations that are similar in form to those of Aristotle. The validity of truth is proven logically. However, the bases of validity are presupposed. They lie outside the court of reason, similar to all the courts of law that we know.
The exemplary validity
When we think of what is valid, we think first of the law, then perhaps of bets, certainly of promises, but hardly of reason. We have also gradually moved away from the image of the court of reason and are now coming to the court in which the law rules. Frege's logic can only help us to a certain extent, because although the court is also about truth, the validity of law is of a completely different nature to the validity of truth. It is true that laws apply, but the laws themselves are not true. So what makes them valid? Legal theorists have different answers to this question. Carl Schmitt, who today is considered to be burdened by his role in National Socialism, distinguished between three types of validity of the law, depending on what the validity is derived from: a norm, a decree or a political order. He tended to favour decision. The element of judgement is undoubtedly important for the validity of the law. However, as a decision can also be arbitrary, violent and unreasonable, decisionism is rejected by many today. Jürgen Habermas has proposed an alternative which, although it does not call upon the court of reason, does call upon the reason of non-violent discourse conducted with arguments. Only at the end of the rational discourse should a decision be made. This model could be called 'rational decisionism'.
These models and others leave open the question of what idea underlies what is valid, be it as a right, a promise, a bet or an exchange rate. My proposal is that what is valid establishes a connection between what is and what should be. Let's take the laws of environmental protection as an example. The destruction of the environment is what is - and what should be is an end to this destruction in order to preserve the environment. The connection between what is and what should be is established by the laws of environmental protection. Another example is promises. When we promise someone something, this promise exists. What should be is its fulfilment. We are obliged to fulfil it. The obligation applies because it establishes a connection between the expression of the promise and its fulfilment. It remains valid until the promise is fulfilled.
The connection between what is and what should be is always different. There is no universal basic structure, no validity in general, only the idea of a connection, which is always different. The context can always look different, adapted to what is. If we know more about the causes of environmental destruction, we can also better achieve the goal of protecting the environment with the help of existing laws. Legislation to protect the environment can always be improved.
This idea is familiar from Kant's Critique of Judgement. There, Kant develops what he calls the "beauty judgement". The power of judgement plays a role in this judgement. It playfully combines reason and imagination, concepts and ideas. There is no predominance of concepts and not simply the overwhelming impression of ideas, but a play between these two forces. The result is valid when we all come to the same conclusion. The exemplary validity of our judgement is a "subjective-general" one. It presupposes a number of things. The most important is what Kant calls "common sense". The common sense contains an ought, as Kant says.20
When we judge, we should be able to agree with how others judge. Applied to the validity of human dignity, we understand the significance of public spirit. If we assume that it is a question of judging a possible violation of this principle, we can only reach a common judgement if we can make use of the common sense, which contains all the prerequisites for our ability to judge, the cultural, religious, scientific, social and political ones. On this basis, we can then arrive at an exemplary, exemplary judgement that is universally valid or at least can be universally valid. However, it is only this judgement and not all possible others whose validity is at stake.
It is interesting that at the end of his critical work, Kant no longer makes use of the Court of Reason. Now one could object that exemplary validity is a basic figure of aesthetic judgement. This is true, but this power of judgement is the basic model of judgement in general. Whatever one thinks about the history of judgement, exemplary validity can be applied to all possible, very different contexts of validity. We do not need the court of reason to gain insight into what is valid.
