The Method of a Truly Normative Legal Science

CHAPTER CONTAINS an argument to the effect that the proper method for legal science depends on what one takes to be the nature of science, the nature of the law and the kind of questions that are addressed in legal science. It starts from three assumptions, namely that

(a)  science is the collaborative pursuit of knowledge;

(b)  the law consists of those norms which ought to be enforced by collective means; and

(c)  the proper standard to determine what ought to be done is what maximises the long-term happiness of all sentient beings (the H-standard).

On the basis of these assumptions the following positions are argued:

  1. Legal science, in the sense of a description of the law, is not impossible for the reason that it is a normative science.
  2. In abstract the method of all sciences, including legal science, is to create a coherent set of positions that encompasses ‘everything’, and therefore also beliefs about the law.
  3. The proper method for a normative legal science consists primarily of the methods of sociology, psychology and economics, because the ultimate question to be answered is the collective enforcement of which norms satisfies the H-standard. The more traditional hermeneutic methods only play a role to the extent that they establish positive law that contributes to happiness by providing legal certainty.


In this chapter I will outline a method for a truly normative legal science. With ‘truly normative’ I mean that this legal science provides the answer to some version of the question ‘what should we do?’ I will argue that the issue of the method for legal science hangs together with views on the nature of science, on the nature of law, on the justification of alleged knowledge, and – as I will argue – in the end with almost everything. The second section of this chapter will be devoted to an argument that the method for a normative science is essentially the same as that of a science that deals with ‘facts’. In this first section I discuss a number of assumptions that are needed to get the argument started. The precise status of these assumptions will be clarified in section III, which deals with the method of normative legal science in particular. Section IV summarises the argument of this chapter.

A.  The Nature of Science

If we want to know what the proper method for legal science is, we should at least have some idea of what we mean by ‘science’.1 Science has to do with the pursuit and accumulation of knowledge.2 Moreover, it aims to systematise this knowledge. How this systematisation takes shape depends on the object of the knowledge. In the case of historical sciences, the system derives from the way in which facts and events explain each other. In the case of physical sciences, the system consists in the laws that are formulated and that are used to explain and predict events and facts, and in the way in which laws are derived from each other. In mathematics, the system consists in the axiomatisation of a subdomain and in the derivation of theorems from these axioms.

A third characteristic of science, which explains other important characteristics, is that science is a social phenomenon. It is impossible to be the only scientist in a field, at least in the long run. Science is a cooperative enterprise aimed at the acquisition, accumulation and systematisation of knowledge. The advantage of science over individual acquisition of knowledge is that scientists can build on the results of their colleagues. To quote Newton: ‘If I have seen further it is only by standing on the shoulders of giants.’3

Let us assume that science is a way in which people collaborate in the pursuit and systematisation of knowledge. If such collaboration is to be possible, several conditions must be met. First it must be assumed that the aspired knowledge is, at least approximately, the same for everybody involved in the cooperation. If everybody would have his or her own ‘truth’, it would be impossible for one person to build on the results of other persons.4 This demand would, in the eyes of many, exclude aesthetics and astrology from the arena of science. Very often the assumption that truth is the same for everybody is made on the basis of another assumption, namely that knowledge describes a world which is mind-independent and therefore the same for everybody (ontological realism). A true description of this independent world would be the same for everybody too. It is possible, however, to assume a truth that is the same for everybody without endorsing ontological realism. Mathematical truth would, according to many, be a case in point.

B.  Science and Method

A second precondition for the possibility of cooperative knowledge pursuit is that there exists, at least to a large extent, agreement on what count as good reasons for adopting or rejecting a potential piece of knowledge.5 Here is where method comes into the picture. For what is a scientific method?

In one sense of the word, it is a way of going about doing science. It is a kind of procedure that is to be followed if the results are to count as ‘scientific’.6 An example of such a procedure would be the empirical cycle as described by De Groot7 or the Herculean method described by Dworkin in the chapter ‘Hard Cases’ from Taking Rights Seriously.8

In another sense, a scientific method indicates what count as good reasons for adopting or rejecting a potential piece of knowledge. Take, for instance, the mathematical thesis known as the Goldbach conjecture,9 that all even numbers bigger than two can be written as the sum of two prime numbers. One mathematician would count on proof to establish the truth of this thesis, while another mathematician would take a large collection of random even numbers, check whether they can be written as the sum of two primes, and decide from that sample that the conjecture is almost certainly true. If they consider their own method as the only legitimate one, these two mathematicians cannot cooperate in the pursuit of knowledge on number theory.

The adoption of a particular method in this second sense boils down to agreement on what count as such good reasons. Since such an agreement is a precondition for science as collaborative knowledge acquisition, a shared method is almost by definition a precondition for science.10

Reasons in general, and therefore also reasons for accepting or rejecting a particular piece of potential knowledge, are facts that are relevant for what they are reasons for or against.11 The adoption of a method is a choice for what counts as relevant. It is also a choice concerning the kind of data that must be collected in order to argue for or against a potential piece of knowledge. For instance, on a hermeneutic method for legal science, the relevant data for a particular legal conclusion might be that this conclusion is supported by the literal interpretation of a statute, which is adopted as an authoritative text. Therefore, a legal researcher should consult this text, and apply, possibly amongst others, a literal interpretation to it.12

The proper way of going about legal research method in the first sense is, to a large extent,13 determined by method in the second sense of the recognition of particular kinds of data as relevant for the issue at stake. It is this second sense of ‘method’ that will be at stake in the rest of this chapter. Science in the sense of collaborative knowledge acquisition is practically impossible without such a method.

C.  Method and the Object of Knowledge

The idea of a method is often connected to disciplines such as law, physics, mathematics, biology, medicine, history, sociology or psychology. In the following I will continue to write about the methods of a discipline, but this is, in a strict sense, incorrect. Which facts count as reasons for or against a conclusion depends on the type of conclusion and therefore on the research question at issue. One discipline may deal with several kinds of research questions and then different methods are relevant in answering these questions. Legal science is a case in point. The question as to what the criminal law of a jurisdiction is – the traditional doctrinal question – differs, for instance, from the question how the contents of the criminal law developed in the course of time – the legal historical question. It is improbable that the same kinds of facts would be relevant to answer these two questions. So, if within a discipline different kinds of research questions are being asked, the issue of method should be focused on a type of research question, rather than on the discipline as a whole.14 For the following discussion of the method of legal science, I will focus on the description of the (contents of the) law of a particular jurisdiction at a particular place and time.15

The methods of a scientific discipline are normally chosen because the participants in the discipline assume that these methods lead to the kind of knowledge pursued in their discipline. A good example is formal logic. One of the questions with which formal logic deals is what the theorems of a particular logical system are. Logicians believe that this question has one correct answer. Moreover, each potential theorem either is or is not a theorem of the system at issue. Logicians cooperate in identifying the valid theorems and by giving reasons (proofs) why the proposed theorems are valid. Moreover, the alleged theorems and the accompanying proofs are published, to share the results with other logicians who can build upon them, and who are also enabled to check whether the alleged theorems have been proven. Logicians consider proofs to be relevant because they assume that proofs lead to conclusions which are true, not only for the person who gave the proof, but also for all other logicians. In fact, they even attempt to prove that proofs lead to true results by showing that a particular proof theory is ‘sound’. There exists an independent test, in the shape of model theoretic semantics, which determines whether a particular theorem is true, and a particular logical calculus is sound (a recommendable characteristic) if its proofs lead to theorems that are true according to the semantics.16

The point of this example is that scientific disciplines tend to assume that there is truth to be had and also that the methods they employ are normally suitable to discover this truth. Formal logicians assume that proofs lead to true theorems; theorists of the physical sciences assume that the cycle of hypothesis formulation, empirical testing of hypotheses, and improving the hypotheses on the basis of the test results, leads to ever better (in the sense of more true) theories,17 and moral philosophers assume that mutual adaption of concrete moral intuitions and general moral principles lead to ever better moral theories.18

The methods of scientific disciplines are often based on implicit theories concerning the nature of the discipline’s objects and the suitability of these methods for obtaining knowledge about objects with that nature. As mathematical theorems are different from physical laws, it takes different data to argue for the truth of theorems than for the existence of physical laws. Changing insights into the nature of a discipline’s knowledge object may lead to changes in method. If, for instance, the law is not (anymore) considered to be an answer to the question of what to do, but rather a body of rules, rights and principles that happen to exist at a particular time and place, we might stop arguing about the contents of the law by pointing out the consequences of particular rules, and revert to the study and interpretation of authoritative texts or the behaviour of leading jurists.

A discipline and its methods are part of a wider body of (hypothetical) knowledge, which includes views on the nature of the discipline’s knowledge objects and theories on how and why particular data are relevant to establish knowledge about such objects. In connection with the proper method of legal science, this would mean that the view concerning this method hangs together with a view on the nature of the law, and a view on which data are relevant to determine the truth – if there is any to be had – of potential pieces of legal knowledge.

At this point I want to mention the possibility that legal ‘science’ does not aim at the pursuit of knowledge about something at all. Many lawyers are involved in keeping the law of a particular jurisdiction in good shape. This is done by describing the law as it is, incorporating recent changes caused by, for instance, new legislation and case law, into the body of legal knowledge, by evaluating the existing law and by proposing changes to it, or even – if one is in the position to do so – by bringing about the desired changes.19 This is an important task of legal ‘science’, and it is benefited by an academic level of dealing with the law, but it is not science in the sense of the word used here of cooperative knowledge acquisition. It is rather a form of highly qualified maintenance of the legal system. There may be some overlap in method with ‘real’ legal science, but maintenance of the legal system is a different discipline from legal science and I will not deal with it here.

D.  Three Views on the Nature of Law

In most disciplines, a method reflects a view of the discipline’s knowledge domain. For instance, in physics it used to be assumed that nature obeys certain ‘laws’ and that these laws manifest themselves in observable phenomena. Observations can be used to induce hypotheses about the laws and to test the laws through predictions of new observations.20 The proper method is therefore to use observations to induce laws from (empiricism), or to falsify predictions (critical rationalism). In mathematics the idea is that the domain consists of a set of theorems that somehow ‘follow’ from the discipline’s axioms. The appropriate method is then to deduce the theorems from the axioms (or to prove, if that is possible, that a potential theorem cannot be proven). Similarly, one would expect the method of legal science to reflect a view about the law.21

i. Purely Procedural Law

It is possible to distinguish at least three fundamentally different views on the nature of the law. One view is that questions about the contents of the law, even ‘easy’ questions, have no true answers and that the law consists merely of a set of acceptable argument forms, such as an appeal to legislation, to case law, to legal principles, human rights, legal doctrine, and the standard canons for legal interpretation and legal reasoning. Legal argument is not aimed at finding the contents of the law, because there is no such a thing. It is aimed at convincing one’s auditorium of a particular legal position. Some arguments are more authoritative than others22 and should therefore be more convincing, but what counts in the end is not whether the correct position was defended – because the correct position does not exist – but which argument was most convincing in the sense of being effective. The law would be, to use Rawls’ phrase, purely procedural,23 with the not unimportant clause that the procedures that constitute the law, the acceptable argument forms and the materials to which they refer – legislation, treaties, case law and custom – to a large extent constrain the possible outcomes.24 The law for a concrete case, or for a case type, would be the outcome of a battle of arguments.25

Legal science in the sense of collaborative knowledge acquisition requires the possibility of agreement. If the law is purely procedural, this possibility can only exist if the nature of the legal procedure constrains the possible outcomes of a battle of arguments to such an extent that only one outcome is viable.26 However, then the law is not purely procedural anymore, because most legal discussions would have only one possible outcome if played by the procedural rules, and then the contents of the law are fixed, more or less in the same way as mathematical theorems are fixed by the axioms and the rules of the proof system. If the law is purely procedural, however, that is if the procedural rules in combination with the contents of the legal sources do not determine the outcomes of legal argument battles, there is no basis for agreement on the contents of the law27 and legal science in the sense of collaborative pursuit of knowledge is impossible.

ii. Law as Social Fact

A second view of the law holds that the law exists as a matter of social fact, independent of what individuals may believe about it, but dependent on what sufficiently many sufficiently important members of a social group think about the contents of the law and think about what others think about it.28 A special variant of this view is that of law as institutional fact, according to which most of the law exists thanks to rules that specify what counts as law.29

This view of law as social fact has two advantages. First, it explains why the law appears to be a matter of fact, independent of what individual persons think of it, and that the contents of law depend on a particular jurisdiction. Second, it explains why lawyers tend to argue about the law as if it already exists and as if two conflicting legal positions cannot both be true.

The view of law as social fact has also an important disadvantage, namely that there would be less law than seems at first sight. If law exists as a matter of social fact, there cannot be more law than is fixed by social reality. In particular there cannot be law about which knowledgeable lawyers fundamentally disagree.30 And yet, such disagreements seem to occur frequently. Does this mean that these lawyers do not disagree about the law, but rather about how the law should be expanded to cover the case at issue? If this is the case, why do these lawyers not clearly separate the two discussions, one about the law that actually exists and the other about the most desirable way to create new law? Somehow the arguments about the contents of the law and what would be desirable legal solutions for types of cases seem to conflate. Is this a matter of methodological confusion, of pious deceit, or is something else the case?

iii. The Normative View of the Law

The third view of the law assumes that something else is the case. According to this view, the law is essentially an answer to the question what to do, and more in particular what to do by means of rules31 which should be enforced collectively, usually by means of state organs.32 Notice that according to this third view, the law is, not what is actually enforced collectively, but what ought to be enforced collectively. To state it in an overly simplified way: the law is an ought, not an is.33 Therefore, I will call this the normative view of the law. On this normative view there is principally no difference between the law as it is, and the law as it should be.34 Moreover, the law would be a branch of morality, if morality is taken as that set of standards that indicate what would be good and right things to do all things considered and taking the interests of all human (sentient) beings into account.35

The obvious advantage of the normative view is that it explains how discussions on the contents of the law often deal with what is desirable. The equally obvious disadvantage is that it seemingly fails to explain how the law is the same for everybody, why law appears to be primarily national law, and how the law is related to such matters of fact as the contents of legislation and of case law, judicial decisions, and social practices such as the canons for interpretation and legal reasoning. This disadvantage does not need to be real, however. The ‘positive’ law, which exists as a matter of social fact, is an important – in fact by far the most important – factor that determines the law in the sense of rules that should collectively be enforced. It is highly desirable that the law can function properly in regulating human society and for that purpose it needs to be stable, the same for everybody, and easily recognisable.36 In practice this means that the law must by and large be positive law.37 The difference with the view of the law as social fact is, however, that positive law is ‘real’ law (‘real law’ in the sense of the law that should be enforced by collective means) not because that is the social practice, but because, and to the extent that, the positive law ought to be enforced collectively.

Moreover – and this has immediate implications for the method of legal science – the positive law is only ‘real’ law to the extent that it contributes to the recognisability of law and to legal certainty. This means that if the ‘positive’ law can only be established by means of some contestable interpretation, it cannot fulfil its coordinating function anymore and loses its presumptive force as law.


In this contribution I intend to outline a method for legal science as a description of existing law,38 on the assumption that the normative view of the law is correct. Legal science would then be a normative science, aiming at the collective pursuit and systematisation of normative knowledge, in particular knowledge which rules should (here and now) be enforced collectively.

This view of legal science has some similarities with, but should nevertheless be distinguished from the view, promoted by Smits, that legal science is normative in the sense that it deals with the question of what the law should be.39 Although Smits is not very explicit about the nature of the law,40 it seems that he considers the law to be a set of rules, etc that exist in social practice. Legal science should, according to Smits, indicate what this practice should be. In my opinion, the ‘real’ law, as distinguished from the merely positive law, is itself an answer to a normative question and legal science as description of this ‘real’ law aims at providing this answer. Despite this difference, the view of Smits on the nature of legal science has an important similarity to my view, because we both assume that legal science deals by and large with the question which rules we should have, or should enforce by collective means.

The method that I apply to formulate the proper method for legal science is to argue why the proposed legal method contributes to the pursuit of knowledge about which norms should be enforced collectively. In particular it is not an analysis of the method used in contemporary legal doctrine. This method is, as is correctly pointed out by Van Hoecke,41 essentially hermeneutic. From the fact that a hermeneutic method is in fact used in the development of legal doctrine, it does not follow that this is the proper method, however. In this sense, I am not a methodological naturalist.42 As I will argue in section II. E., the method that is actually used in doctrinal legal science is no more than a starting point in the process of deciding which methodological positions stand up to critical scrutiny.

A.  Why Normative Science Seems Problematic

It is a popular view that normative science is not well possible.43 The reason is generally some form of non-cognitivism concerning normative (and evaluative) issues. It is customary to distinguish between the realms of is and ought and to be an ontological realist with respect of the realm of the is, and to be a non-realist with respect to the ought. With regards to is-matters, there would be a mind-independent reality which is the same for everybody44 and which makes every factual proposition true or false.45 With regard to ought-matters, such a mind-independent reality would be lacking. To state it bluntly: whether we agree about it or not, there would be a true answer to every question of fact, while there is no such true answer concerning normative questions. What ought to be done would not be a matter of facts that are the same for everybody, but a matter of taste, or of choice, which may have a different outcome for different persons, even if they are all fully rational. There is no common ground which can function as a foundation for agreement and where there is no ground for agreement, so runs the argument, there is no room for science.

The same issue can also be approached from a logical point of view.46 To justify an ought-conclusion by means of a deductively valid argument, at least one of the premises must be an ought-sentence too. Moreover, for a successful justification, the premises of the justificatory argument must be either true, if they are factual, or justified. Since presumably normative premises cannot be true, they must be justified, but this justification requires an argument with at least one normative premise, which must be justified . . . etc. However long the justificatory argument chain is made, it never touches solid ground in the form of premises which have all truth values. This line of argument has become so familiar that attempts to base normative conclusions on solely factual premises are discarded without much discussion as committing the ‘naturalistic fallacy’.47 I will argue that this familiar line of argument against the possibility of a normative science either is much weaker than is usually assumed, or hits purely ‘factual’ science just as hard as it hits normative science. The central piece of my argument is a theory about the nature of justification.

B.  Positions

There are many different things which can be justified, such as beliefs, actions, decisions, verdicts, etc. On first impression one might think that these different objects of justification require different forms of justification, but this impression is only correct to a limited degree.

All forms of justification can be reduced to variants on justification of behaviour (including forbearance). This is obvious for actions, and since decisions and verdicts can be brought under the category of actions (taking a decision, or giving a verdict with this particular content), it should be obvious for decisions and verdicts too. The same counts for using rules.

It is somewhat less obvious for beliefs, but the justification of a belief with a particular content can be interpreted as the justification of accepting this belief content. Accepting something can, for justificatory purposes, be treated as a kind of mental action. And just as it is possible to accept belief contents, it is possible to accept goals, values and principles.

It is even possible to continue along this line, by treating the justification of the different forms of actions as the justification of accepting ‘that these actions are the ones that should be performed (under the circumstances)’.48 In this way, all forms of justification can be treated as the justification of accepting ‘something’. As a catch-all term for things that can be mentally accepted, I will from now on use the word ‘position’.

Building on this definition, I will use the expression ‘position set’ for the set of all positions accepted by a person.

C.  Local and Global Justification

In the literature on legal justification, justification has sometimes been pictured as a deductively valid argument.49 In such an argument the conclusion (what is justified) must be true given the truth of the premises. The idea behind this kind of justification is that the ‘justifiedness’ of the premises is transferred to the conclusion, analogous to the way in which the truth of the premises is transferred to the conclusion in more traditionally conceived deductive arguments.

It seems to me that this picture is mistaken in at least two ways. First, because it suggests that ‘being justified’ is a characteristic of positions that is similar to truth, only somewhat ‘weaker’. Second, because it overlooks the essentially global nature of justification. In a deductively valid argument, the conclusion must be true if the premises are true. This means that the truth of the conclusion is guaranteed by the truth of the premises, and that nothing else is relevant for this truth.50