Sunday, April 11, 2010

Natural Right, Natural Law, and Positive Law: Aristotle’s Influence on St. Thomas Aquinas


Since Thomas Aquinas, most arguments concerning natural right and natural law find their way back to Aristotle. Indeed, Aristotle pioneered a new concept of rights that were never discussed before his time. Whereas Plato bound the individual to his duty within the organ of the state, Aristotle argued that the individual deserved the right to enjoy an equality based society (Miller 87). Each individual had rights that existed within nature by definition (natural law). In addition to the discussion of natural law, Aristotle is credited for giving a detailed account of positive law as well.

Many common interpretations of Aristotle’s theory on natural right, natural law, and positive law are seen through the eyes of Aquinas; however, this approach has drawn much criticism. There is no question that Aquinas was heavily influenced by Aristotle, but there are several convincing arguments that question whether an accurate view of Aristotle is seen through the lens of Aquinas’ interpretation; in other words, “we must be wary of reading back into Aristotle Aquinean doctrines” (Shiner 188).

In this paper I intend to examine whether the Aquinean interpretation of Aristotle’s concept of natural right, natural law, and positive law is adequate to quell harsh criticism. I will do this by first addressing Aristotle’s concepts of natural right, natural law, and positive law. Second, I will explain how Aquinas defined natural right, natural law, and positive law. Third, I will show how Aquinas was influenced by Aristotle, and how – although Aquinas was influenced by Aristotle – he varied from Aristotle’s idea. I will conclude that while Aristotle is credited for helping to form the foundation of natural right, natural law, and positive law, these legal ideas cannot fit perfectly into the Aquinean interpretation without some adaptation.
Aristotle: Natural right, natural law, and positive law.

While the difference between natural law and positive law is a relatively easy distinction, there are often common misunderstandings between Aristotle’s concept of natural rights and natural law. The differences are often subtle, but there are differences nonetheless. To understand these I will include a variety of definitions that are associated to Aristotle’s understanding of natural right, natural law, and positive law, and then I will show how these theories fit together.

Natural Right

There are many competing theories concerning what Aristotle meant by natural rights. While some claim that Aristotle argues that a natural right is a type of inherent or “inalienable right” (as expressed in the American Declaration of Independence), others argue that a natural right comes into existence through the state. There is even a third theory that defines natural rights through an interpretation of natural justice and says that rights are “‘founded on the nature of man’, in distinction from merely conventional rights” (Miller 88). Bernard Yack defines Aristotle’s concept of natural right as “the idea that for every particular situation there exists one inherently just state of affairs against which we can measure the justice of our actions and opinions” (Yack 216).

While one argument denies that Aristotle has a distinct theory for natural rights and another argues that Aristotle has a working theory of natural rights – neither side disagrees on any substantive issue of interpretation (Miller 88-9). This said, I will argue that Aristotle had no concept of a natural right in connection with an “inalienable right,” but that, for Aristotle, the state, as a natural entity, determines men’s natural rights in establishing justice: “But justice is the bond of men in states, for the administration of justice, which is the determination for what is just, is the principle of order in political society” (Pol. 1253a37-9). Through just action, the state determines the natural right of the individual in maintaining order in political society. Because man is given natural rights through the state, this does not contradict Aristotle’s claim that man has rights that exist by nature – for the polis itself is a natural entity.

Natural Law

To Aristotle, the law is a type of justice (Pol. 1255a21-3). In defining natural law, Aristotle wrote that the “Universal law is the law of nature. For there really is, as every one to some extent divines, a natural justice and injustice that is binding on all men, even on those who have no association or covenant with each other” (Rhet 1373b6-9). The natural law is that which defines what is inherently just. However, in saying this, we encounter another problem. Bernard Yack argues that
Nature provides us with a standard to determine which individuals should participate in political communities. It has equipped human beings (or at least some human beings) with capacities that lead them to develop communities in which they rely on one another’s judgments bout the intrinsic merits of their actions. It has not, however, equipped them with a final standard against which to measure those judgments (Yack 217).

In one sense, it appears that Aristotle argues that nature itself directs the individual toward a moral imperative; however, Yack argues instead that Aristotle is not defending the existence of natural, inherently correct standards of justice. “[Aristotle] is, instead, arguing that the need for citizens to make and argue about judgments of the intrinsic justice of their actions is something that develops naturally within political communities” (Yack 216). Therefore, to Yack, natural law is the naturally occurring principle that originates within the polis, when the state inherently questions the intrinsic justice of its actions in the political community.

Positive Law

Aristotle argues that it is necessary to make a complete classification of just and unjust actions, and we do this “by observing that [actions] have been defined relatively to two kinds of law” (Rhet. 1373b1-3). We already know that one of these kinds of law is the natural law, but Aristotle will now define his positive (particular) law. “Particular law is that which each community lays down and applies to its own members: this is partly written and partly unwritten” (Rhet. 1373b4-6). The positive, or ‘particular’, law is that law that is expressly defined by the community. This law may be a written rule, or it may be a social expectation.

Everything Together

I have already argued that the state determines the natural right of the individual in maintaining order in political society, but is this accurate? Is this Aristotle’s intended argument? If man is by nature a political (social) animal (Pol. 1253a1-2), then what else comes to man by nature? As Yack argued above, nature provides a standard for determining how individuals should participate in political communities, and nature has equipped some human beings to develop communities; however, nature has not provided a final standard of moral judgment (Yack 217).
As the state defines the ultimate standards of just judgment (natural right), the state will continue to establish justice through law (natural law). However, not all social questions are answerable through an appeal to justice. Natural justice, for instance, cannot answer whether it is more just to drive on one side of the road than another, such an instance is a matter of conventional law – or, rather, positive law. Customs, traditions, and other written rules that are not specifically identified with natural law or justice are matters of positive (conventional) law and justice.

Aquinas and Natural Right, Natural Law, and Positive Law

Natural Right

Rather than considering the topic of a ‘right’, Aquinas wrote primarily concerning the term jus. A person can translate jus through Latin to mean a ‘right’; however, the political concept and use of ‘right’ was not in Aquinas’s lexicon (Lisska 228).
The Aquinean version of natural right – as contrasted with the modern philosophical concept of rights – is given through an objective/subjective distinction. “Aquinas’s account of jus entailed that a matter of fact was determined to hold; from that factual situation, moreover, a certain relation in terms of justice comes about”; in other words, “jus means, so Aquinas suggests, ‘that which is right’, which in turn means ‘that which is just’. Thus, jus refers to an objective state of affairs” (Lisska 229). This is distinguished from the modern concept of a right that “refers to a subjective ‘claim’ which a person might assert regarding something due to the person” (Lisska 229).

In Aquinas’s own words he explains that “jus – which is the same as the just – is a certain work which is proportionate to another according to some method or mode of equality” (Summa Theologiae, I-II q. 57, a.2). In short, Aquinas’s use of jus was not an external relation of two or more persons on the basis of things, but is the basis of external relations (Lisska 231).

Natural Law

According to Aquinas, every creature that has an end also has a nature whose fulfillment is in their nature. This is to say, for example, that man, who is made to find the good, finds happiness in the fulfillment of his nature. Man makes moral judgments to naturally achieve an overall good. Aquinas repeats Aristotle’s concept that man is a social animal; however, Aquinas did not speak of a social contract, but that we are born into social networks and political systems. The moral rule – or natural law – consists in behaving well in these networks and systems (McInerny).

Positive Law

For Aquinas, the positive law is the human law. The positive law must find some root within the natural and justified law; otherwise, Aquinas harkens back to Augustine who argues in De Libero Arbitrio (1.5): “It is the case that a law, which is not just, is not a law at all” (lex inuista non est lex). Man may admonish each other and establish rules of conduct to maximize justice according to the rules of reason; however, once a positive law is found in contradiction to justice (natural law), then that human law is null-and-void.

Aristotle’s Influence on Aquinas and Their Differences

Christopher Martin once noted concerning Aristotle’s influence on Aquinas that “St. Thomas is an Aristotelian. His basic concepts and categories are those of Aristotle, and when they are developed beyond the point at which Aristotle left them, they are developed in an Aristotelian manner” (Martin 4). There are many similarities between Aristotle’s concepts of natural right, natural law, and positive law; however, it is important to acknowledge the differences. Wrote Paul E. Sigmound,
In this description of the natural law Aquinas takes a number of Aristotelian concepts and combines them in a way which is different from the way that Aristotle himself used them. Whether or not he was faithful to the spirit of Aristotle may be argued, but a comparison of Aquinas discussion of natural law with the relevant passages in Aristotle’s Nicomachean Ethics and Politics reveals that Aquinas has combined quite disparate elements in Aristotle… into a new synthesis that makes the determination of natural ends a central consideration in the development of Aquinas’s theory of natural law (Sigmound 69).
Differences in Aristotle and Aquinas

Between the two philosophers, Aristotle is more positive than Aquinas. Whereas, for Aquinas, the moral imperative and sense of justice within natural right and natural law exists in a universal ethereal realm, Aristotle’s concepts of natural right and natural law are rooted in a systematic process naturally dictated from the governing body. Whereas Aquinas’s version of positive law requires a strict adherence to an ethereal moral and just code in natural law, Aristotle’s sense of justice is lawfulness.

For Aristotle, there is no sense of an unjust law that is not a law (lex inuista non est lex), for the just person is lawful – even if the law he is following is unjust. To Aristotle, “there are such things as unjust laws, and so lawfulness cannot provide a standard of what is just. Even if we obey the law, we may be doing what is unjust, because the law itself may be unjust” (Kraut103). This interpretation of Aristotle’s rejects the non-est-lex concept behind Aquinas’ relationship between natural law and positive law – for Aquinas believes that once the moral law is known, any human laws in violation of the natural moral law are invalid and non-binding (as though they never existed).


While it is tempting to interpret Aristotle in terms of “natural law” and “positive law” – because of Aristotle’s talk concerning the “unwritten law” and “natural justice” – these concepts are not the same types of reason. Natural law and positive law are concepts born out of medieval legal theory – namely, these concepts find philosophical refuge in the words of Thomas Aquinas. While Aquinas was unarguably influenced by Aristotle, we cannot juxtapose Aquinean natural law with Aristotle’s natural justice (Shiner 188).

This paper has superficially covered certain necessary points to show that Aristotle’s connection between ‘law’, ‘convention’, and ‘nature’, are not synonymous with Aquinas’s concept of natural law and positive law. Aristotle’s views on ethics, law, and politics are primarily organic – with the citizens and state, and their enacted laws and social decisions – and are a part of the “natural” world (Shiner 189).

Works Cited

Finnis, John. Natural Law and Natural Rights. Oxford: Clarendon, 1986. Print.

Kraut, Richard. Aristotle: Political Philosophy. Oxford England: Oxford UP, 2002. Print.

Lisska, Anthony J. Aquinas's Theory of Natural Law: an Analytic Reconstruction. Oxford:
Clarendon, 1996. Print.

Martin, Christopher. The Philosophy of Thomas Aquinas. London: Routledge, 1988. Print.

McInerny, Ralph. "Aquinas, Saint Thomas." Stanford Encyclopedia of Philosophy. Web. 06 Apr. 2010. .

Miller, Fred D. Nature, Justice, and Rights in Aristotle's Politics. Oxford: Clarendon, 1995. Print.

Sigmound, Paul E. "Thomistic Natural Law and Social Theory." Calgary Aquinas Studies (1978). Print.

Yack, Bernard. "Natural Right and Aristotle's Understanding of Justice." Political Theory 3rd ser. 18 (1990): 216-37. JSTOR. Web. 2 Mar. 2010. .

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