An Analysis of St. Thomas Aquinas's Position on the Relationship Between Justice and Legality.

• Author: Chng, Kenny

I INTRODUCTION

St. Thomas Aquinas, the Angelic Doctor, was renowned for his genius. His masterful exposition of Christian theology, drawing upon Aristotle's philosophy to form a solid intellectual foundation for Christian ideas, has formed the core of the Catholic Church's teaching for almost a thousand years. Beyond Christianity, Aquinas has also exerted a major influence on legal philosophy. As the foremost expositor of natural law theory, natural law theorists to the present age owe a great debt to Aquinas's discussion of law in his Treatise On Law. However, one aspect of Aquinas's legacy has generated an inordinate amount of contention--his view of the relationship between justice and legality. Is an unjust law a law at all? Modern natural law theorists taking contradictory positions all claim to be faithful to Aquinas's ideas on the matter. Some, taking a view that has been described as "strong natural law theory", argue that Aquinas believed that the injustice of a law renders it legally invalid. Others, taking the position of "weak natural law theory", argue that Aquinas perceived an unjust law as legally defective but still a law in a secondary sense. Even legal positivists, the traditional opponents of natural law theory, have proposed interpretations of Aquinas's thoughts on the matter. They cannot all be correct.

This paper is directed at investigating what really Aquinas's position was on the relationship between justice and legality. It will do so by taking a detailed look at Aquinas's Treatise On Law, the broader context of the Summa Theologiae ("the Summa") within which the Treatise is situated, and Aquinas's methodological and definitional approaches. The outline of the paper is as follows. First, it will describe the different positions that modern natural law theorists have taken on the relationship between justice and legality, with a view to identifying the key conceptual differences between strong and weak natural law theory. Second, it will briefly describe how Aquinas's thought on this issue has been interpreted by modern legal theorists, to illustrate the extent of disagreement between interpreters of Aquinas. Third, it will provide an overview of Aquinas's arc of argument in his Treatise On Law, to provide context for the subsequent deep-dive into Aquinas's thought. Fourth, the paper will formulate a set of questions to be resolved, corresponding to the key conceptual differences between strong and weak natural law theory, and will then evaluate Aquinas's text, context, and methodology to determine how Aquinas's thought bears on these questions.

II NATURAL LAW POSITIONS ON THE RELATIONSHIP BETWEEN JUSTICE AND LEGALITY

While natural law theorists have offered a variety of interpretations of the relationship between justice and legality over the ages, two main schools of thought have crystallized--theorists have termed these schools "strong natural law theory" and "weak natural law theory". (1) The focus of this section will be to identify the key differences between these two schools of thought as a foundation for the subsequent analysis of Aquinas's thought.

It will be useful to first set out the common ground between both schools of thought, before articulating their differences. All natural law theorists affirm that law's legality depends in some way on its moral content. (2) Put another way, in the natural law view, the substantive justice of a law has an impact on its legality. (3) Different natural law theorists have different views on the degree of this impact, but all natural law theorists unanimously affirm the existence of such an impact. This affirmation sets natural law theory apart from legal positivism. Legal positivists, in contrast, affirm that the legality of law is independent of its moral content--the issues of law's morality and its legality are distinct analytical inquiries, and one can achieve a comprehensive and accurate account of law without reference to its moral content. (4)

The key difference between strong and weak natural law theory lies in their conception of the precise impact of morality on legality. The strong natural law view interprets the morality of law as an "existence condition" for law, akin to how having three sides is a necessary requirement for a triangle. (5) Just as a shape comprising more than three sides cannot be a triangle, the character of legality cannot be possessed by a manifestly unjust norm. (6) As argued by Gustav Radbruch, a manifestly unjust law is not a law at all. (7) A law, despite being validly passed by a legitimate law-making authority, is not a law at all if it surpasses an extreme level of injustice. (8) Thus, a law that is substantively unjust is not just morally or legally defective--it cannot properly be called a law at all. Since unjust laws are not laws at all, on this view, they cannot possess any obligatory force.

It should be noted at this juncture that some influential legal positivists, such as John Austin, have cast the position of natural law theory on the relationship between morality and legality as an extreme version of strong natural law theory--that all promulgated laws are necessarily moral. (9) This conception of strong natural law theory is certainly not one that strong natural law theorists hold themselves, for good reason--such a proposition is easily disproven as an empirical matter. Strong natural law theorists do accept that legitimate law-making authorities can promulgate rules which are unjust, as an empirical fact about their law-making power. (10) However, strong natural law theorists would hold that even if validly promulgated, these unjust rules are not laws. (11)

Weak natural law theorists, on the other hand, interpret the morality of law as a "defectiveness condition" of law. (12) In other words, the injustice of a law makes the law defective as a law. (13) This should be carefully distinguished from the view that the injustice of a law makes a law morally defective--this would be a decidedly uninteresting proposition which cannot be meaningfully distinguished from the legal positivist position. (14) Rather, the weak natural law position is that the injustice of a law makes a law legally defective. Thus, in contrast with the strong natural law position, morality does not spell a necessary existence condition for a law, but goes toward whether a law is one in the fullest sense, or is merely a law in a secondary sense of the term. On this view, it is possible to identify true legal propositions in a legal system without regard to morality, by considering whether they have been "authoritatively issued" and whether they are "socially efficacious". (15) But if one seeks to evaluate whether these propositions are indeed laws in the full sense, the justice of these laws must be taken into account. (16) As a matter of law's obligatory power, the weak natural law view holds that unjust laws do lose obligatory force--they do not "bind in conscience". (17) However, in contrast to the strong natural law view, since these laws remain laws in a secondary sense, they are still capable of engendering obligatory force, albeit in a weaker sense. They can engender what John Finnis describes as legal-moral obligations, which are based on a recognition that an overall system of social ordering through law promotes security and stability, and thus can be a basis for a collateral moral obligation to obey an unjust law. (18)

With the positions thus laid out, four key differences between the strong and weak natural law positions can be identified.

First, the two positions take a different definitional approach to law. The strong natural law position sees a definition of law as the specification of a set of conditions that must be fulfilled--failing any of which, the precept in question is not a law at all. The weak natural law position applies the central case method in its definition of law. (19) It sees the criteria for a definition of law as a set of conditions which specify what law is in the fullest sense--and if certain conditions are not met, the precept in question can still be validly described as a law, but in a less central sense.

Second, as a consequence of their different definitional approaches to law, the two positions take a different view of the relationship between justice and legality. The strong natural law position views justice as a necessary condition for a norm to be a law, the absence of which means that a norm is not a law at all. In contrast, the weak natural law position views the justice of a law as a benchmark for determining whether it is a law in the focal sense. An unjust law remains a law, but is one in a less central sense.

Third, the two positions take different views on the effect of injustice on a law's obligatory force. The strong natural law position views injustice as removing all obligatory power from a putative law--if an unjust law loses legal character altogether, it cannot possess any obligatory power as a law. The weak natural law position, in contrast, accepts that an unjust law can nevertheless still engender collateral moral obligations as a valid law in a legal system providing a means of social ordering.

Fourth, the strong natural law position views the positing of a law--i.e. the promulgation of a law by legitimate law-making authority--as a necessary but insufficient condition for a precept to be identified as a law. In contrast, the weak natural law position views positing as a necessary and sufficient condition for a precept to be identified as a law, such that there can be true legal propositions which are immoral. (20)

III COMPETING INTERPRETATIONS OF AQUINAS

Was Aquinas a strong or weak natural law theorist? There is no express answer to this question that can be found in his writings, for the simple fact that these theoretical categories did not exist in his time. As such, theorists since Aquinas have offered competing interpretations of...