Zōon Politikon’s Doppelgänger: Comparing the Political Existence of Man in the Political Philosophies of Aristotle and Aquinas

Writing more than 1650 years after Aristotle’s death,  Thomas Aquinas inhabited a world that would have been absolutely foreign to Aristotle. Whereas Aristotle lived before the age of monotheistic religion, Aquinas was a Catholic priest of the Dominican Order. Whereas Aristotle still lived in an age of city-states (poleis), Aquinas lived in an age of empire. Whereas Aristotle spoke Greek, Aquinas’ mother-tongue was Latin. Given these vast cultural, historical and political gulfs, it seems obvious that the Thomistic re-articulation of the Aristotelian definition of man as a “political animal” (zōon politikon) (Aristotle 1998a, 1253ª1-6; 1253a7-20; 1278ᵇ14-29), in which man came to be defined as a “social and political animal” (animal sociale et politicum)  (Aquinas 1987a, I.1), would differ vastly in terms of meaning relative to its predecessor. This paper sets out to prove the opposite. Through a comparative analysis which shows that the zōon politikon and the animal sociale et politicum have almost identical meanings, this paper argues that the significance of any differences between them are marginal in light of their considerable similarities.

Aristotle’s doctrine of the four causes is a scientific framework which facilitates the development of reliable, scientific explanations of natural and conventional phenomena in terms of their genesis and development. However one evaluates the doctrine, it’s clear that an inquiry into the material, formal, efficient and final causes of a given pair of entities would provide an ideal standard from which to undertake an evaluation of their similarities or differences. For this reason,  the strategy of this paper is to compare the meaning of Aristotle’s and Aquinas’ definitions of man by asking: What are they made made out of? What are they to be? What produces them? What are their purposes? In turn, this inquiry into the four causes of the zōon politikon and the animal sociale et politicum sets the stage for an evaluation of the relative significance of any similarities or differences between them.

To consider what man is made up of is no facile exercise since the assertion that the form of a given phenomena is only intelligible as something articulated through matter is the central Aristotelian critique of Platonism. The form of a substance refers to the inner source of developmental change which determines the ideal shape of what a given substance is to be  after  its “coming-into-being has been completed” (Aristotle 1998b, 1252ᵇ25-3). For example, the form of a frog which is contained in the tadpole expresses the tadpole’s potential to become a frog. The observation that an architect applies “the general idea of a house to the shape of this or that house” also expresses this point (Aquinas 1987b, 95. 2). Insofar as the architect constructs the house out of building materials according to a mental blueprint, she is like a sculptor whom shapes matter in order actualize the form of an envisioned statue (Aquinas 1987b, 93.1). The fact that matter can be arranged and transformed such that it becomes something else illuminates the potential of things which exist “by nature” to be transformed through the developmental and creative processes that culminate in the actualization of a particular form.

This same logic can be used to understand the nature of man’s existence as a political and/or social animal. Specifically, the “self-evident proposition” that “man is a rational being […] by its nature” expresses the intricate relationship between matter (potentiality) and form (actuality) articulating the zōon politikon and animal sociale et politicum (Aquinas 1987b, 94. 2). Matter (blood, flesh and bone) and form are amalgamated in man, a composite substance consisting of synthesis of matter (body) and form (soul), whose nature is to become a  “rational being” (Aristotle 1998b, X.8).

To illuminate the psychic contours of the the zōon politikon’s and animal sociale et politicum’s rational being, Aristotle and Aquinas distinguish between human and animal life. (Aristotle 1998b, 1253ª7-20; Aquinas 1987a, I.1). Although man is not the only political animal, since other animals  also exhibit a high-level of social organization (e.g, naked mole rats and bats), man’s existence is more political of necessity than other eusocial animals as a result of man’s unique capacity for reason (logos [Aristotle] or ratio [Aquinas]) (Aristotle 1998a, 1253ª7-20). Unlike other animals that possess instinctual knowledge of those things necessary for survival, man is a rational-animal whom must use its distinctly human faculties (reason, intelligence, speech) and live in groups to survive (Aquinas 1987b, I.1).  Unlike non-rational animals whom can use their voice to signify their perceptions of “what is pleasant or painful […] to each other” (Aristotle 1987b, 1253ª7-20), man’s range of communication encompasses and extends well beyond the communication of the experience of pleasure or pain (Aquinas 1987a, I.1). Man’s unique capacities for reason and intelligence allows for the emergence of the faculty of reasoned-speech through which the rational-animal can articulate their perceptions of what is “good or bad, just or unjust”  (Aristotle 1998b, 1253ª7-20; Aquinas 1987a, I.1). The capacity to use intellect and speech to perceive and articulate evaluative judgements concerning justice are the complementary and indeed inseparable functions characterizing man’s psychic essence as a rational being. Such abilities not only distinguish man from the rest of the animal kingdom, they reflect the purposeful character of nature as a whole which “operates for the best” (Aquinas 1987a, I.2) and thus “makes nothing pointlessly” (Aristotle 1998b, 1253ª7-20).

The capacities for “universal reason” and speech are essential elements of human nature which reside in the most unqualifiedly valuable part of man: its soul (Aquinas 1998b, 1286ª15-20, 1323ᵇ12-21; Aquinas 1987a, I.1-2; I.12). Man’s soul consists of two parts, an appetitive non-reasoning part and a reasoning part (Aristotle 1998b, 1339ª14-20; Aquinas 1987a, I.1-2). The reasoning part of man’s soul is further divided into two parts which correspond to the capacities for practical reason and theoretical reason (what Aquinas calls “speculative reason”) (Aristotle 1998b, 1339ª14-20; Aquinas 1987b, 93.4). Aristotelian and Thomistic political philosophy not only subordinates body to the soul, appetites to reason, and practical reason to theoretical reason, they view the hierarchy characterizing these elements as natural and therefore just because they accord with relations of rule observed in the natural world wherein “the worse  part is always for the sake of the better” (Aristotle 1998b, 1253ª15-1255ª5,1339ª14-20; Aquinas 1987a, I.1-2). In other words, from the standpoint of the ethical life of the rational-animal, the prioritization of soul over body, reason over non-reason, speculative reason over practical reason is always choice-worthy since to attain what is highest is natural for man (ibid.).

Aristotle and Aquinas thus have virtually identical conceptions of the material and formal causes of the zōon politikon and the animal sociale et politicum. Much like how the form of an oak tree is contained within an acorn, the form of the rational being is contained within the political animal and represents the idealized nature that man can realize when its “coming-into-being has been completed” through the virtuous use of its distinctly human capacities for intelligence, reason and speech. However, Aristotle and Aquinas also share similar conceptions regarding the three efficient causes of man’s genesis.

In both the Aristotelian and Thomistic philosophies of nature, God is the efficient cause of of the universe which contains the cosmos and the natural world (Aristotle 1998a, 1323b15-30; Aristotle 1998b, 10.8; Aquinas 1987b, 93.1). Although Aristotle and Aquinas acknowledge that things which exist “by nature” as well as various man-made artifacts arise as the direct result of other external efficient causes (such as the sexual union of man and woman), the key point is that they share in the view that an unmoved-mover is the external efficient cause of man’s genesis in the last analysis (Aquinas 1987b,  94.2; Aristotle 1998b, 1253ᵇ12-21). Specifically, both theorists trace the beginnings of everything to God, the self-sufficient and incorporeal entity whom possesses perfect happiness because it pursues the highest form of activity: the contemplation of His own being (Aristotle 1998a, 10.8). But apart from these external efficient causes, Aristotle and Aquinas also possess virtually identical conceptions of internal efficient cause of the rational-animal’s genesis.

Man’s nature as a rational-animal renders its political and social existence as a sort-of “natural necessity” (Aquinas 1987b, I.1; Aristotle 1998b, I.2 1252ª25-35). Unlike other eusocial animals, man lacks the anatomical appendages that would facilitate self-defense and nourishment (claws, fur, wings, teeth, horns, stingers). Man also lacks the instinctual knowledge about the natural environment that might otherwise facilitate less social modes of living (ibid.). As a result of such “deficiencies,” men must use their uniquely human faculties of intellect, reason and speech as well as their bodies to continuously create and re-create an environment which is adapted to the life of a political and social animal through the use of technology and science. Given that man cannot use his reason to invent such tools in insolation, it is necessary for men to “live in society so that one person can help another and different men can employ their reasons in different ways” (Aquinas 1987a, I.1). Man’s capacity to use language to communicate can thus be understood as a function of this fact that men can scarcely survive in isolation just as fish can scarcely live without gills.  This is why Aquinas writes the fact that it is necessary for man to live in society “is most clearly demonstrated by the fact that man uses words to communicate his thoughts fully to others” (ibid.). At the species level, they must associate with one another to obtain the necessities of life because as rational-animals they lack any capacity for solitary existence; therefore, it is “natural” for men to live in association with his fellows  and man’s capacities for reason and speech can be understood as natural tools because they facilitate this task (Aquinas 1987b, I.1).

In this sense, the household and family, which are “naturally constituted to satisfy [the] everyday needs” pertaining to nourishment and procreation, emerge not from deliberate choice but rather for “the sake of survival” and thus also exist by nature (Aristotle 1998b, 1252ª25-35,  1253ᵇ10-15; Aquinas 1987a,  I.1). The city-state (polis [Aristotle] or civitas [Aquinas])  also comes into existence for the “sake of living” although it serves a higher purpose. Specifically, the city-state is natural  because it provides for “whatever is needed for life,” such as “common defense and mutual aide against enemies,” by virtue of the fact that it encompasses all other associations (such as the household) (Aristotle 1998b, 1252ª1-10, 1252ᵇ25-30, 1280ª24-31; Aquinas 1987a, I.1). Through the institutions of law and education, which are (ideally) designed to inculcate the habits necessary for the development of dispositions conducive to communal and virtuous living, the city-state also neutralizes the negative affects that inevitably arise as men use their uniquely human capacities (reason, speech, and intelligence) to articulate and pursue their private goods (Aquinas 1987a,  I.1; Aristotle 1998a, I.3 1252ª30-35; Aristotle 1998b, X.9 ). Hence, Aquinas drawing on Aristotle observes that

As the Philosopher [Aristotle] says: “Man is the noblest of animals if he is perfect in virtue, but if he departs from law and justice he is the worst.” For unlike other animals man possesses the weapons of reason which he can use to satisfy his passions and base instincts (1987b, 95.1).


The implication here is decidedly Platonic. The institutions of the city-state have an educative function, they seek tame the negative consequences that can arise through the use of reason for corrupt ends. By cultivating the habits through which the human faculties can be perfected and used as tools of virtue and practical reason, they help to prevent the degeneration of man into the “most unrestrained and savage of animals”  (Aristotle 1998b, 1253ª 20-40).

As captured by the expression “[n]ature makes nothing incomplete or pointless,” the city-state can thus be understood as an association which realizes the ends of nature in so far as it facilitates the gradual perfection of the zōon politikon and the animal sociale et politicum which naturally develop in the direction of their final purpose (Aristotle 1998b, 1256ᵇ19-21; Aquinas 1987b, 97.1). Yet although each category of being realizes the purpose of nature as a whole by actualizing its particular purpose,  an observable hierarchy of ends exists in the natural world which terminates at the highest good–i.e., the self-sufficient end which is desired for its own sake–such that the realization of subordinate ends for the sake of master ends as well as the rule of the naturally inferior by the naturally superior accords with nature (Aristotle 1998b, I.1-5). However, although Aristotle and Aquinas agree that  perfect happiness is the highest end of man, they diverge with respect to the precise nature of that happiness (Aristotle 1998a, X.7; Aquinas 1987b, 91.4).

The purpose of zōon politikons political life  is eudaimonia (successful living), a disposition that arises from the cultivation of good character through the ongoing pursuit of action willfully undertaken in accordance with the virtue proper to the life of a rational-animal, i.e., reason, for the sake of living the good life (Aristotle 1998a,  X.6-10). Because it creates the conditions where more than one individual can live successfully, Aristotle regards the polis as the highest and most godlike end to attain in the sphere of politics (Aristotle 1998a, I.1-2). However, whereas Aristotle regards the polis as the most authoritative community by virtue of the fact that it exists for the purpose of living happily and nobly and thus “aims […] at the good that has the most authority of all”  (Aristotle 1998b, 1252ª2-7, 1280ᵇ40),  Aquinas regards the polis (or civitas) as a mere intermediate end of the animal sociale et politicum whose final purpose, the “enjoyment of God,” is attainable through a life “lived in accordance with virtue” (Aquinas 1987a, I.14). The animal sociale et politicum thus has two ends: a temporal end in this life which can be realized in and through the civitas as well as a spiritual end in the afterlife. The apparent distinction between Aristotle’s and Aquinas’ conceptions of man seems to turn on the diverging purposes (teloi) of the zōon politikon and the animal sociale et politicum. Whereas the good life of the former consists in the well-living (eudaimonia) that occurs in the polis through the development of good character, a condition that arises as one willingly undertakes rational activity in accordance with the highest virtue (Aristotle 1998a,  X.6-10), the good life of the latter consists of “the final happiness (beatitudio) in the enjoyment of God which awaits him after death” (Aquinas 1987a,  I.14).

The temporal and spiritual ends of the animal sociale et politicum reflects the synthesis between revelation and reason characterizing Thomistic political philosophy. As the objective foundation of “truth and right” (morality),  the divinely revealed law which “cannot err” because it was given to man by God, allows men to resolve moral dilemmas with certitude, supports and justifies the authority of eternal law, natural law and thus human law, forbids sin and reveals eternal bliss (beatitudio) to man as its final end (Aquinas 1987b, 91.4). One of the major consequences of this synthesis is the endowment of the animal sociale et politicum  with certain rights and obligations as a subject of divine law.

The logic here is straightforward. Since natural law reflects the rule of reason, which in turn reflects the “rational plan of divine wisdom,” it provides an objective standard from which to evaluate the justice of existing human laws and political regimes (Aquinas 1987b, 93.1). Political regimes and human laws which exist for the sake of the common good are just from the objective standard of natural law since by directing men to their appropriate end through the pursuit of the common good (i.e., through the pursuit of peace through unity) they reflect “the order of divine providence which directs everything in the best way” (ibid.). By contrast, political regimes and human laws which exist for the sake of the private interests of the ruler are unjust (and indeed evil) from the objective standard of natural law because they contravene “divine goodness” by turning men away from their appropriate ends (Aquinas 1987b, 96.4; 1987a, I.2). As a subject of divine and natural law, the animal sociale et politicum thus acquires a very limited right of revolution/rebellion within the context of intolerably unjust regimes  as well as a limited right to civil disobedience in relation to unjust human laws (a point which I elaborate further elsewhere) (Aquinas 1987a, I.6).

However, it would be incorrect to conclude that, in light of its endowment with such rights and duties, the animal sociale et politicum’s existence is significantly different than the zōon politikon’s  given that the conditions under which the invocation of these rights and duties would be recognized as legitimate are narrow.  Aquinas is clear that human law which contravenes natural law, either by 1) infringing the “human good” (such as what occurs when a law serves the private interests of the ruler) or by 2) contravening divine law, does not bind conscience. However, the rational-animal is nevertheless compelled to obey unjust human law which infringes the common good where disobedience could give rise to scandal or disorder. This constraint would not be altogether unreasonable were it not for the fact that a decision regarding “what is or what is not useful to the city” in terms of the common good is the sole prerogative of the ruler  (Aquinas 1987b, 96.6). Moreover, although the existence unjust human law which contravenes divine law gives rise to a positive duty to disobey (Aquinas 1987b, 96.4), the scope of this duty is also decidedly narrow given that divine law primarily consists in ceremonial laws concerning proper worship  (e.g., rituals concerning the proper sacraments) and the Ten Commandments (Aquinas 1987b, 100.1; 1987b, 96.4). The right of revolution is even more tightly circumscribed.  Here Aquinas appeals to the principle of lesser evils which dictates that the lesser of two evils should be chosen where one must choose between two unappealing choices.  According to this principle, it’s better to tolerate life under a moderately unjust regime even when that regime is tyrannical than to instigate revolution (Aquinas 1987a I.5-6). Where life under an unjust regime has become intolerable, Aquinas counsels the rational-animal to proceed through the established channels to limit the ruler’s powers (or depose of him altogether) or to appeal to god where this is impossible (ibid.).

Hence, although the animal sociale et politicum acquires a number of rights and duties by virtue of their subjection to divine law, the significance of such endowments are radically diminished by the narrow scope of their application. A reflection on the zōon politikon’s divinely ordained supernatural end, a good which exists beyond the well-living facilitated by the polis, also neutralizes the significance  of the animal sociale et politicum’s divinely acquired rights and duties (Aristotle 1998a,  I.5, X.6-9).

I’ve already suggested that the zōon politikons purpose is eudaimonia (successful living), a disposition that becomes possible in the polis whose institutions provide free-men with the leisure to cultivate good character through the ongoing pursuit of action undertaken in accordance with the virtue proper to the life of a rational-animal (Aristotle 1998a, X.6-10). This life and its corresponding form of happiness, however, is not the best life and thus form happiness possible for the zōon politikon (ibid.). Rather, it represents the mean between the worst life and the best life which Aristotle   counsels the virtuous political scientist to aim at if only because it represents what is practically possible for free-men under certain ideal circumstances to achieve.

The “life of philosophy” is superior to the “vulgar life” pursued for the sake of pleasure and the “political life” pursued for the sake of honor and civic virtue because, as the result of activity undertaken in accordance with the highest virtue–i.e., contemplative reason as the best and most divine of the human faculties–it gives rise to perfect happiness (Aristotle 1998a, I.5, X.7). Although the goods of the vulgar life and the political life are indispensable, as the ends of the former are subordinate to the latter which in turn are mere means to the life of philosophy, both ways of being lack the self-sufficiency and leisureliness possessed by the philosophic life and are thus mere means to contemplative reason, an activity which is characterized as divine because it reflects “the activity of God, which surpasses all others in blessedness” (Aristotle 1998a, X.7-8).

We thus see in the “good man,” whom by definition pursues a life of contemplation, a set of possibilities that run more-or-less parallel to the narrowly circumscribed rights to civil disobedience and revolution the animal sociale et politicum is endowed with.  While the good man does not possess a right to civil disobedience or revolution, indeed this would go against Aristotle’s overarching goal of casting political science as discipline which seeks to preserve constitutions, he can also appeal to the objective moral standards provided by nature to determine the justice of particular laws and political regimes and also to consider how to act in the face of natural injustices. Aristotle’s assertion that the virtues of the good man and of the good citizen are not “unqualifiedly the same” suggests that the good man in an unjust regime would necessarily be a bad citizen whom would not abide its unjust laws as a good man (Aristotle 1998b, 1277ª5-15). Since any action contrary to nature is “ignoble and inimical to virtue,” a good man would neither tolerate being ruled by a “natural slave” nor being forced to  live a “life of a vulgar craftsmen” (Aristotle 1998b, 1329ᵇ39-40) especially given the impossibility of atoning for any deviations from virtue (Aristotle 1998b, 1325ᵇ1-10).

The comparison of the four causes of the zōon politikon and animal sociale et politicum  illuminated an intricate relationship between the formal and final causes of the rational-animal. Man’s potential to realize his nature by becoming a fully-constituted rational being, a condition which qualifies him as a citizen and thus as a “natural ruler,” is a function of his ability to act in accordance with his particular virtue (reason) for the sake of living well  (Aristotle 1998b, I.5). The existence of “natural slaves” whom “share in reason to the extent of understanding  […] but do not have it,” serves as a reminder that those things which are said to exist “by nature” do not always realize their potential (ibid.). In this sense, the zōon politikon and the animal sociale et politicum are not significantly different articulations of the political existence of man because they each give rise to a form of political life governed by the same exclusionary logic. Natural slaves, vulgar craftsmen and women–in short, all of those whom are regarded as incapable of becoming rational beings due to some (presumed) deficiency in their cognitive faculties–are included in the  polis/civitas as partial members of the political community (“qualified citizens”). However, although such beings furnish the necessary conditions of political life, they are not regarded as genuine parts of the  polis/civitas  because they lack the cognitive faculties needed to live a life of politics (bios). Hence, natural slaves, vulgar craftsmen and women are not only debarred from “unqualified citizenship” and thus relegated to the sphere of “mere life.” Since happiness only extends as far as contemplation does (Aristotle 1998a, X.6), they are also debarred from the “happiness that accompanies virtue” as well   (Aristotle 1998b, 1328ᵇ25-1329ª39).  A parallel logic of exclusion operates in Thomistic political philosophy such that “defective” beings are subject to eternal law, natural law, divine law and human law and excluded from participating in the form of life which allows man to realize his purpose in this life and the next.

On the surface the differences between the zōon politikon and the animal sociale et politicum appear vast given the latter’s endowment with various rights and duties as a subject of divine law. By  comparing the Aristotelian and Thomastic definitions of the political being of man through the  lens of the doctrine of the four causes, this paper has argued that these definitions of man are virtually similar in meaning. By highlighting the limitations placed on the animal sociale et politicum’s rights to civil disobedience and revolution, the zōon politikon’s obligations as a good man in an unjust regime, as well as the logic of exclusion which would prevent certain lives from realizing the ends of man by relegating them to the sphere of mere life, this paper has argued that any difference between these definitions of man are largely insignificant relative to their similarities.



Aquinas, Thomas. 1987a. “On Kingship or the Governance of Rulers.” In St Thomas Aquinas on Political Ethics, Translated and Edited by Paul E. Sigmund, 14-29. New York: Norton and Company.


Aquinas, Thomas. 1987b. “The Treatise on Law.” In St Thomas Aquinas on Political Ethics, Translated and Edited by Paul E. Sigmund, 44-59. New York: Norton and Company.


Aristotle. 1998b. Politics. Translated by C.D.C. Reeve. Indianapolis: Hackett Publishing Company.


Aristotle. 1998a. Nicomachean Ethics. Translated by David Ross. New York: Oxford University Press.


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