Thought experiments featuring angels have for long found their place in philosophy. Medieval philosophers, for example, have used thought experiments involving angels to discuss the possibility of having cognitive access to the essence of things and to clarify the relation between thought and language.Footnote 4 In legal and political philosophy, scenarios involving angels or other morally-driven subjects appear occasionally, at least since Aristotle.Footnote 5 Within this context, perhaps the most famous occurrence is Madison’s claim that ‘if men were angels, no government would be necessary’.Footnote 6
Closer to our time, what became known as the ‘society of angels thought experiment’ has received a fair amount of attention in contemporary analytical jurisprudence. Several legal philosophers – including prominent figures such as Hart,Footnote 7 Raz,Footnote 8 Finnis,Footnote 9 and GardnerFootnote 10 – have presented variations of this thought experiment while discussing the role of coercion in law. In this discussion, the thought experiment is supposed to both work as a counterexample to the claim that legal systems are necessarily coercive and to provide support for the view according to which non-coercive legal systems are possible. Here is how the thought experiment goes:
(Society of Angels): Imagine a society of morally perfect angels. Despite being morally perfect, the angels in this society can still make use of a legal system to coordinate numerous aspects of their public lives and resolve whatever disputes may arise. Nonetheless, the angels in this society need not be coerced to cooperate with one another and to achieve their social goals. Hence, the angelic legal system need not resort to coercion to properly work.Footnote 11
It is worth noting that the society of angels thought experiment is not itself an argument for the claim that non-coercive legal systems are possible;Footnote 12 it is simply a description of a scenario where a non-coercive legal system exists. The scenario, of course, is used in an argumentative context. Namely, it is used to provide a reason in support of the claim that a non-coercive legal system is possible.
Yet, it is not entirely clear what it means to say that the thought experiment provides a reason in support of the claim that a non-coercive legal system is possible. There are least two worries. The first concerns the relevant meaning of ‘possible’. The second relates to our justification for believing that the scenario depicted by this thought experiment is possible in the relevant sense. I deal with the first worry in the following subsection and with the second in sequence.
What Kind of Possibility?
Joseph Raz is probably the most well-known user of a variation of the society of angels thought experiment. He claims that ‘[e]ven a society of angels may have a need for legislative authority to ensure co-ordination’Footnote 13 and that courts would be useful in such scenario.Footnote 14 Raz’s remarks on the thought experiment can help us find the relevant notion of possibility for the discussion.
Raz asks rhetorically whether a non-coercive legal system is possible. But his answer is prefaced with a caveat: the relevant notion of possibility at stake is not human possibility. For Raz, and for many others, a non-coercive legal system is ‘humanly impossible’.Footnote 15 With this Raz most likely means that a non-coercive human legal system is nomologically impossible;Footnote 16 it is impossible given the biological and psychological dispositions of human beings.
Though humanly impossible – Raz continues – a non-coercive legal system is ‘logically possible’.Footnote 17 It is so because, according to Raz, it is plausible to conceive ‘other rational beings who may be subject to law, who have, and who would acknowledge that they have, more than enough reasons to obey the law regardless of sanctions’.Footnote 18 From this, it can be inferred that Raz presents the thought experiment as a reason for the logical possibility of a non-coercive legal system.
Even though Raz explicitly states that the relevant notion of possibility is logical, we should not interpret his statement literally. A given proposition is logically possible if, and only if, it is not a logical falsity. Thus, we can identify logical possibilities and impossibilities just by looking at the logical form of propositions. That an object is square and not square at the same time is a logical impossibility. But that Usain Bolt is a cake is a logical possibility – the proposition ‘Usain Bolt is a cake’ is not a logical falsity.Footnote 19 As we can see, logical possibilities are too permissive. For that reason, despite being true, the claim that a non-coercive legal system is logically possible is trivial and probably uncontentious. There are, therefore, good reasons to neither interpret Raz’s claim nor the discussion revolving around the claim that legal systems are necessarily coercive as being about the logical possibility of a non-coercive legal system. This possibility is too broad to be of any theoretical significance.
The best way to interpret Raz’s and similar claims – I’ll argue – is interpreting them as claims of metaphysical possibility.Footnote 20 Something is metaphysically possible if, and only if, it is consistent with the most fundamental metaphysical principles and categories that structure reality.Footnote 21 When we ask, for example, if it is metaphysically possible for Usain Bolt to be a cake, we want to know if, given how reality is fundamentally arranged, a circumstance where Usain Bolt is a cake is genuinely a case where Usain Bolt, and not someone or something else, obtains. That is, whether whatever it takes for being Usain Bolt is compatible with what it takes to be a cake.
Metaphysical possibility differs from both nomological and logical possibilities. It is broader than nomological possibility, but not as broad as logical possibility.Footnote 22 That is, there are metaphysical possibilities which aren’t nomological possibilities, and logical possibilities which aren’t metaphysical possibilities. For example, it is metaphysically possible for Usain Bolt to run faster than the fastest of cheetahs even though it is nomologically impossible.Footnote 23 And it is metaphysically impossible for Usain Bolt to be a cake, although it is logically possible. It is difficult to find uncontroversial examples of mere metaphysical possibility. Despite this difficulty, intuitive examples such as the one where Usain Bolt is a cake help us to make sense of the notion.
We’ve seen that construing the claim that a non-coercive legal system is possible as a claim about logical possibility makes the relevant discussion trivial and uninteresting. That doesn’t happen when we construe it as a claim about metaphysical possibility. In fact, doing so helps us better understand the broader discussion in which the debate about whether legal systems are necessarily coercive is a part.
The debate over whether legal systems are necessarily coercive is often assumed to be part of a broader inquiry about the nature of law.Footnote 24 And, arguably, questions about the nature of something aren’t questions about the way in which we think and speak about something; ‘questions about the nature of some thing are paradigmatically metaphysical questions’.Footnote 25 They are, in other words, questions about the object-level: questions about things, as they occur in reality; not questions about how we represent or conceptualise things, questions about the representational-level. Now, if we see – as I think we should – the debate about legal systems being necessarily coercive as a debate about the metaphysics of legal systems, it becomes clear why the notion of metaphysical possibility is the relevant one. If we are interested in the metaphysics of legal systems – in the nature of law, as it were – we need to find out if the kind of thing we happen to call ‘legal systems’ could have been non-coercive and still remain the same kind of thing.
Nevertheless, not all legal philosophers who discuss the nature of law in general, and the necessity of coercion to legal systems in particular, see themselves as engaged in metaphysical debates. Quite the opposite. As Plunkett and Shapiro have recently suggested, and as confirmed by many works in the methodology of legal philosophy,Footnote 26 ‘many [legal] philosophers (…) harbor deep suspicion about metaphysics and don’t spend much (if any) time working on it.’Footnote 27
Instead, many legal philosophers prefer to see both the debate about the nature of law, and the debate about the necessity of coercion to legal systems, as conceptual debates. They are interested, for example, in investigating if our concept of legal system, as we have it, applies to a non-coercive institution such as the one imagined in the society of angels thought experiment.Footnote 28 Thus, for those philosophers, the relevant sense of possibility for the discussion is not metaphysical; it is conceptual.
The notion of conceptual possibility is elusive and is used by philosophers in different ways.Footnote 29 Most common among legal philosophers is the following notion of conceptual possibility: something is conceptually possible if, and only if, it is consistent with our conceptual framework; with how we currently and ordinarily represent the world.Footnote 30 Following this interpretation, a non-coercive legal system is conceptually possible, if, and only if, our concept of legal system extends to a non-coercive system.
From what I’ve said above, we can see that the relevant sense of possibility for the discussion about the society of angels thought experiment hangs on a broader debate about the proper object of a theory about the nature of law. Adjudicating between these two conceptions of the object of a theory about the nature of law (conceptual and metaphysical) is beyond the scope of this paper. However, let me clarify why it strikes me as more plausible, or at least more interesting, to see metaphysical possibility as the relevant sense of possibility for the society of angels thought experiment.Footnote 31
First, it is pertinent to point out a mistake in a reason for preferring the conceptual approach sometimes found in the works of legal philosophers. Some have favoured the conceptual approach in virtue of thinking that it fares better with two interrelated assumptions about legal systems they consider sound: the assumption that legal systems are social constructs and the assumption that social constructs are nothing but what people collectively think and speak about them.Footnote 32 The thought is that if legal systems, as social constructs, are entirely constituted by mind dependent facts about our linguistic or conceptual practices and behaviour, then all the truths about legal systems, including truths about what is necessary and possible about legal systems, would be found in our thought and talk about legal systems. If that is the case – the argument goes – then relying on the notion of conceptual possibility seems to make more sense.
This is a non-sequitur. From the assumption that legal systems are entirely constituted by the sort of mind dependent facts mentioned (an assumption that is much more controversial than some legal philosophers would have us believe),Footnote 33 it doesn’t follow that the notion of conceptual possibility is better suited than metaphysical possibility. Both notions would elicit exactly the same results in this scenario: they would be explanatorily equivalent. This is because, in this scenario, whatever is metaphysically true of legal systems is co-extensive with what is conceptually true of it: legal systems are the sort of thing that is entirely constituted by the way people think and speak about it.
Ironically, the very move that was supposed to get rid of metaphysical talk about legal systems ends up with a notion of conceptual possibility that is explanatorily on par with the notion of metaphysical possibility. What is more, the very assumption that legal philosophers rely on to establish the priority of conceptual modality – i.e., the assumption that legal systems are entirely constituted by facts about our thought and talk – is metaphysical. To substantiate it, legal philosophers would have no other option but to engage in the very kind of metaphysical discussion they wanted to eliminate with the adoption of the conceptual approach. All suggests that the aversion some legal philosophers have to metaphysical discussions and the notion of metaphysical possibility is uncalled for. If that is the case, there seems to be no clear advantage in preferring the conceptual approach. But there are costs.
The most obvious one is being revisionist about a methodology that most philosophers arguably rely on when they make other types of claims about legal systems. For example, philosophers have claimed that typical legal systems are pervasively coercive,Footnote 34 that typical legal systems coordinate behaviour,Footnote 35 that some of its norms are unjust, etc. These claims are meant to be taken as claims about typical legal systems; as claims directly about the kind of institutions that exist and apply to us. These aren’t claims about how we think or speak about typical legal systems; claims about our representation of typical legal systems. It strikes me that this is also how most people would see these claims.
If this is so, then why assume that things should be radically different when we discuss features that are necessary to legal systems? More to the point, why assume that when discussing the necessity of coercion to legal systems we should no longer see this as a discussion about legal systems but instead as a discussion about our representation of legal systems?
These worries disappear if we adopt the metaphysical approach. Adopting the metaphysical approach has the advantage of making discussions about necessary features of legal systems methodologically continuous to the kind of discussion philosophers usually have when discussing features of typical legal systems. In other words, the metaphysical approach doesn’t call for a reorientation in the methodology most philosophers already rely on to discuss more common questions such as ‘Are typical legal systems pervasively coercive?’.
The society of angels thought experiment gives us a reason for believing in the possibility of a non-coercive legal system. If I’m right about what I’ve said in this subsection – and to make modal discussions about legal systems methodologically continuous to other common philosophical discussions about them – we should treat the society of angels thought experiment as giving us a reason to believe in the metaphysical possibility of a non-coercive legal system.
Yet, nothing I mentioned in this subsection clarifies how we can be justified in believing that the scenario depicted in the society of angels thought experiment is in fact metaphysically possible. This is the subject of the next subsection.
Knowing Possible Legal Systems
Knowledge of metaphysical possibility is a central topic in modal epistemology. Some philosophers argue that we know what is metaphysically possible through our ability to conceive scenarios. According to this account, if something is conceivable, it is metaphysically possible: conceivability entails metaphysical possibility.Footnote 36 Others reject the conceivability account and defend that our knowledge of metaphysical possibilities is just a special case of our knowledge of counterfactuals.Footnote 37 According to this account, the way in which we know if something is metaphysically possible is not different from the way in which we know the truth of common counterfactual propositions – e.g., ‘If it had rained, the game would have been cancelled’.
Adjudicating between different approaches to the epistemology of modality is not something I intend to do in this paper. For the present purposes, I’ll only show how we can (at least) justifiably state that a non-coercive legal system, as depicted in the society of angels thought experiment, is metaphysically possible. I’ll do so while trying not to take a stake in deep controversies in modal epistemology.
My claim is that background knowledgeFootnote 38 and ordinary experience can help us to justify the belief that a non-coercive legal system (as depicted by the thought experiment) is possible. Here is how it can help. First, background knowledge and experience set an initial baseline for what is metaphysically possible: whatever is actual is metaphysically possible. If a thought experiment has features that are actual, we can infer that at least those features are metaphysically possible.
Second, background knowledge and experience can be used as defeasible guides to analyse the plausibility of metaphysical possibility claims. It is plausible to assume, based on our background knowledge, that the English legal system could have had fewer rules than it actually does. But it is not plausible to assume that it could have had no rules at all. That would clash with our experience and background knowledge about the role and the structure of legal systems. Yet, it is a defeasible guide because proximity to what we know cannot be a conclusive reason; we are fallible and have limited knowledge. Our experience and background knowledge may be proven wrong by stronger considerations, such as a sound theory about the nature of legal systems. But in the absence of such considerations, and given all we currently know and have experienced about legal systems, we wouldn’t be justified in believing that a rule-less legal system is metaphysically possible.
Having said that, here are some considerations that illustrate how background knowledge and ordinary experience can help us to justify the claim that a non-coercive legal system, as depicted in the society of angels thought experiment, is metaphysically possible.
First, we know that the degree of coerciveness of legal systems can vary from system to system and within the same system at different time frames. These variations can be drastic (as when a military coup or a radical change in the political orientation of a government takes place) or mild (as when the legal system abolishes a particular kind of punishment). This means that we know that legal systems can adjust (and usually tend to adjust) the use and the availability of coercive mechanisms to respond to particular circumstances and needs. Which means that it is metaphysically possible for a legal system to drastically reduce its degree of coerciveness when coercion proves unnecessary for that legal system to work (or for any other reason).
We also have background knowledge about what sorts of activities fall within the scope of legal systems. We know that actual legal systems don’t merely punish, deter crimes, or compel people to do things against their will. As pointed out by philosophers and social scientists, a significant part of the activities performed by legal systems have little to do with coercion.Footnote 39 Legal systems play an important role in solving coordination problems and in disseminating information about people’s empirical and normative expectations.Footnote 40 Legal systems regulate contracts, wills and marriage, separate private from public, design tax schemes, regulate the allocation of public goods, and do things like the determination of frequencies of radio and TV, the form of traffic signs, the processes involved in elections and in the transition of governments, assign roles and role obligations, and so on. We know, therefore, that non-coercive activities are a non-trivial part of what legal systems are used for.
A feature of the thought experiment that may give rise to some doubts is moral perfection.Footnote 41 We need not, however, worry too much about it. A detailed account of moral perfection is unnecessary for the thought experiment to run. All that is needed is that moral perfection entails that angels would cooperate with one another when cooperation prevents the occurrence of morally bad outcomes and when cooperation helps angels to achieve morally good outcomes. This can be grounded on our background knowledge and ordinary experience: morally good people are cooperative when cooperation helps them in achieving a morally better state of affairs; a fortiori, morally perfect people would also be cooperative in the same circumstances.
Now, take both the fact that angels are cooperative and the fact that legal systems tend to reduce their degree of coerciveness where coercion is proven unnecessary for the system to work. From these facts, it is plausible to conclude that a normative institutional system in a society of angels could have a null degree of coercion. The difficult part, however, is moving from this conclusion to the claim that the system present in the society of angels is indeed a legal system.
What can grant some plausibility to this claim is the large overlap between the social needs that the system in the society angels helps to fulfil (and is purported to fulfil) and the social needs actual legal systems do fulfil. A society of angels might still have the need to create rules to allocate property, to regulate contracts, wills, taxation, to solve small and large coordination problems related to public goods, political processes, the organization of common space (including the organisation of traffic, zoning, signals, etc), assigning roles, allocating risk, settling disputes, and many other non-trivial activities that fall within the scope of the activities performed by actual legal systems.
Given the proximity between the institutional system present in the society of angels and our legal systems, there is a reason to believe that angels have a legal system, and not a different kind of institution. The thought experiment, however, shouldn’t be taken as a silver bullet to decide the question of whether non-coercive legal systems are metaphysically possible. The reason one can extract from the thought experiment is defeasible and it must be weighed against countervailing considerations.
Insofar as it is used to provide a defeasible reason for the metaphysical possibility of a non-coercive legal system, the angelic thought experiment is in good order. Some philosophers, however, are suspicious about this thought experiment and have attempted to undermine it. The next section discusses the main objections presented against the angelic thought experiment.