Human nature and Justice in Plato and Rawls

Introduction

Rawls and Plato are temporally and philosophically quite distant from one another. Yet there is something to be learned from a comparison of their political philosophies—specifically, Rawls’ justice as fairness and the theory of justice as developed in Plato’s Republic. In this essay, I compare the implications of the conceptions of human nature and human differences for Plato and Rawls’ normative theories of justice. I aim to show how their conceptions of justice flow from their conception of human nature, and what causes the diverging development of their theories of justice.

Every determinate difference is grounded in a similarity—so too for Rawls and Plato’s theories of justice. Both develop the contents of their conception of justice by describing a well-ordered society, that is to say, an ideally just socio-political order that is ideal precisely because it is structured and governed by the principle(s) of justice.

Now, to describe such a society requires an explanation of what human beings are like in order for such an idealized society to be possible. After all, if the question of justice concerns how we ought to live together, then it is not unreasonable to assume that this ‘we’ refers to us—that is, human beings. And since we are engaged in philosophy, asking what human beings are like is not a request for a thorough empirical report on every individual dead and living member of the human species in all its diversity. On the contrary, what is sought is the similarity underlying the differences among human beings; in other words, an account of human nature. Without relying on either a crude essentialism or a defining property, the least that can be said is that the concept of human nature refers to certain feelings, behaviors, or capacities that humans tend to share.[1]

But a distinction needs to be made when speaking of human nature: namely that between human nature in the sense of what humans beings are and in the sense of what they couldbe. As MacIntyre remarked in After Virtue, the end of ethics is to realize the good life by enabling the transition from the former —“untutored human nature” (to borrow his phrase)—to the latter—ideal human nature.[2]

As we shall see, both Plato and Rawls see a just society as a prerequisite for attaining the good life. The state provides the means (in Rawls’ case) or the guarantee (in Plato’s) for realizing one’s nature. But the difference between the two echoes MacIntyre’s diagnosis; namely that Enlightenment ethics rejected teleological morality and with it any substantial notion of human nature which serves as the guiding principle for ethics. This goes hand in hand with the birth of liberalism. In liberal thought, Sandel states, a just society is characterized by its refusal to base a political order on any single conception of the good life.[3] Perhaps counterintuitively, the aim behind such a refusal is to enable the realization of a characteristically modern conception of human nature: that of human beings as free and autonomous, having the capacity to define its own ends through the power of reason.

As we shall see, Plato and Rawls both view the capacity for reason as a politically significant aspect of human beings—but both also see that being human also consists of other sources of motivation; identity, morality, bodily desires, or otherwise. Both look at how humans are and how they could be. Plato gives an account of the motivational structure of the human psyche, and differentiates types of characters based on different configurations of this structure. Rawls invokes what he calls the Aristotelian Principle, which is to explain what most deeply motivates human beings when urgent and essential needs have been fulfilled. Both think that citizens need to foster a certain sense of justice. Both theories have an account of what it means/what is needed to flourish in the ideally just society. They agree that there is not one single life that is good for everyone. Rather, what constitutes the good life depends on a person’s natural assets/talents.

In this paper I shall argue that the divergence between Plato and Rawls’ conceptions of justice is a result of how Rawls values the capacity for rationality and what that entails. The fundamental difference between Plato and Rawls lies in the latter’s commitment to respect personal freedom; the freedom to choose one’s own life (within the constraints of right) compatible with the same freedom for everyone else. To demonstrate this, I shall first give a reading of the connection between human nature and justice in the Republic. In the second part, I shall draw the same connection within Rawls political liberalism.

Human nature and justice in the Republic

Justice, in the Republic, is the virtue of the soul (335c), and is assumed to be isomorphic to justice as the virtue of the city.[4] It is defined as having and doing one's own work, and not meddling with what is not one's own (433b). This conception of justice is arrived at by an appeal to nature.

The Greek Conception of Nature

For Plato, a just city is one that is ordered “according to nature” (428e). So what does nature mean here? The Greek conception of nature is not the same as the modern conception of nature as the realm of causality, which forms the object of the natural science. For the Greeks nature is a source of normative authority. Christine Korsgaard puts this difference succinctly, stating that “for Plato and Aristotle, being guided by value is a matter of being guided by the way things ultimately are.”[5] A thing’s nature, in the Greek view, is the “internal principle of growth that makes a thing what it is,”[6] that which ultimately explains a material thing’s activity.[7]

Human nature in the Republic

Plato, in the Republic, explains things’ natures in terms of function. A thing’s “work” or function (ergon) is that which only it can do, or which it can do best (352d-353a),[8] and everything that has a function has a corresponding virtue. Virtue or excellence is what makes a thing perform its function well (353c).

Applied to living beings, and thus also humans, nature refers to the soul (psuche). The function of a soul is living (353d), which it does by “directing and guiding the body.”[9] Foreshadowing the tripartite psychology of book IV, the work of “managing, ruling, and deliberating, and all such things”(353d) are also attributed to the soul.[10]

Plato applies “nature” (phusis) to humans in two ways. In the first, generic sense, human nature refers to common features not produced by intentional human agency.[11] We see the appeal to nature in this generic sense at the start of the construction of the ideal city. A society (i.e. city) is formed, Socrates says “because each of us isn’t self-sufficient but is in need of much.” (369b, my emphasis). Each human being needs a variety of goods in order to live, and none can fulfill all of these needs by themselves. Cities, then, are a product of human nature considered merely as the kind of living beings humans are. Nature in the second sense indicates an individual’s natural, i.e. inborn aptitude for a social function. When asking how the division of labor should be established, Socrates remarks that “[…] each of us is naturally not quite like anyone else, but rather differs in his nature; different men are apt for the accomplishment of different jobs.” (370a-b) Thus, for Plato, it seems that humans are naturally (i.e. functionally) equal, qua human, but inequal with regard to their natural aptitude for social functions. The division of labor, the structure of social cooperation, is drawn according to human nature in the second sense.

Because the aim is to construct the ideal city, each social function should be performed in the best possible way: each should perform only one task, because this is the best way to develop one’s proficiency in that task (the principle of specialization). The question, then, is to outline which natures are to be assigned to which classes. This brings us back to the principle of justice that underlies the above mentioned conception of justice as “the minding of one’s own business” (433a). This is established through the principle of specialization: one person, one task according to natural aptitude. (433a) Justice in the city—social justice—, consists of a harmony in which each class performs its function according to nature (433a).

The Tripartite Theory of the Soul

The psychology of book IV explains more determinately how humans can differ in their natures, and how this maps onto the division of labor of the ideally just city. Departing from the analogy between justice in the city and justice in the soul, city and soul therefore must be structurally isomorphic. And indeed, book IV presents the tripartite theory of the soul (434d-435c), which specifies the soul’s structural components. There are three parts of the soul: reason, spirit, and appetite.[12] Applying the principle of justice to the soul, the rank and function of each part are deduced: each part of the soul must perform the function it is naturally best suited for. The proper role of reason is to govern the soul, because reason, by nature, is able to determine what is truly beneficial for the whole and its parts (433e, 441e). The proper role of the spirited part, then, guided by normative reason’s knowledge, is to suppress the motivational force of appetitive desire when the latter threatens to meddle in reason’s business, i.e. to steer the soul. Finally, then, the proper role of the appetitive part is to obey the spirited part. Justice thus consists in this harmony amongst parts. Conversely, injustice in the soul occurs when appetite grows to overpower spirit and reason, breaking the hierarchical order.

Justice in the City and the Soul: moral psychology and political legitimacy

Analogous to these types of natures, the Republic’s conception of justice presents us with three distinct but complementary ideals of citizenship (taken broadly as membership in a political community),[13] corresponding to the three natures in their virtuous forms. The auxiliaries’ role is to support the rational guardians by enforcing their wisdom and procuring resources necessary for the producers. The auxiliaries must undergo a moral education that ensures they correctly discern between friend and foe and have the correct opinion about what is advantageous to the city. (book III) The producing class is driven by the appetitive part of the soul, which desires food, drink, sex, and wealth. Their task is to produce the material goods necessary for the city's survival. Justice in the soul for the producers means obeying the spirited part, which in turn is guided by the rational part. The wisdom-lovers become guardians and make the city wise, the honor-lovers become auxiliaries and make the city courageous, and the money-lovers[14] produce the necessities of life. Finally, the city is moderate because each class and its members knowingly and willingly accept the city’s hierarchy and their own place in it. The combined virtues embodied by the respective classes’ members constitute justice in both the city and in the souls of its citizens.

At the level of the city, this hierarchical view of reason’s role justifies the rule of the philosopher-kings, as they are seen as uniquely capable the virtue of wisdom, which consists in discerning the true, objective interests of the community as a whole, i.e. the Good. The auxiliaries and producers, lacking the capacity for philosophical reason, are relegated to roles that support the stability and functioning of the city. Plato's model of justice is thus inherently exclusionary, as it limits participation in political decision-making to those deemed capable of rational insight.

Thus, as we have seen, the principle of specialization is a perfectionist principle because it aims to organize society and its institutions in such a way as to maximalize the different forms of excellence that its citizens are capable of. A person’s place in society, what is demanded of them and owed to them according to justice, is determined by one’s natural assets. The ideal city is an epistocracy. Its form of government is instrumentally justified.

Having examined Plato's naturalistic approach to justice, we now turn to Rawls' contrasting view. We will explore how Rawls' conception of persons as free and equal shapes his theory of justice, and how this differs fundamentally from Plato's hierarchical model.

Human nature and justice in Rawls’ liberalism

When we ask the difference between two things, we could name an infinite amount of varieties. This question is thus implicitly about which differences are significant. What differences matter for justice as fairness? According to Rawls, citizens mainly differ in four respects. They differ in: moral and intellectual capacities and skills, physical capacities and skills, conceptions of the good, and last and least, tastes and preferences.[15] Contrary to Plato, however, such natural inequality is not a justification for a social hierarchy for Rawls. For Rawls, what matters is freedom and the commitment to reciprocity.

“What the theory of justice must regulate is the inequalities in life prospects between citizens that arise from social starting positions, natural advantages, and historical contingencies.”[16]

For Rawls, society is also aimed at providing the needs that different individuals, as citizens share. This conception of common need, as that which is to be fulfilled by social cooperation includes the material necessities of life. Indeed, like Plato, this is a result of our common humanity, in the sense of the kind of organisms we are. But Rawls’ conception of common need is more expansive.

This is because Rawls’ liberalism is a response to a historical problem, namely the fact of reasonable disagreement, which results in reasonable pluralism.[17] The fact of reasonable pluralism refers to the idea that free and equal people (an conception to which we shall return later), employing their reason in good faith and to the best of their ability,[18] will inevitably hold diverse and often conflicting comprehensive (ethical, political, metaphysical) doctrines which express a conception of the good life.[19] Posing this fact as the central problem of political philosophy is what fundamentally differentiates Rawls’ philosophy (and other liberalisms) from Plato’s or any other pre-modern political conception of justice. The essential difference between Plato and Rawls’ conceptions of justice then lies, as Rawls himself puts it, in the fact that Rawls’ liberalism acknowledges and aims to accommodate the fact of reasonable pluralism; instead of holding, like Plato, that there is only one conception of the good life which must serve as the organizing principle of society.[20]

At the root of the recognition of reasonable pluralism is a certain ideal of human beings. Namely, human beings as free and rational, and equal in virtue of that freedom and rationality.

Ideal human nature

Taking reasonable pluralism as both given and desirable entails a refusal to identify rationality with any particular conception of the good life. If the free exercise of reason results in pluralism, then rationality alone is an insufficient basis for adjudicating between competing rational claims for political authority.

Rawls aims to find justice for a democratic society consisting of free and equal citizens.[21] Part of such freedom is to be regarded by oneself and others as a self-authenticating source of valid claims.[22]

For Rawls, this basis of citizenship is the recognition of persons “as free and equal in virtue of their possessing the two moral powers to the requisite degree,”[23] whether this power is realized or not. In contrast to Plato, citizens need not be morally perfect in order to realize ideal justice.[24] Citizenship is not defined by standards of perfection, but by a minimum degree of capacities. In his conception of a well-ordered society, Rawls assumes that citizens have, “at least to the essential minimum degree, the moral, intellectual, and physical capacities that enable them to be fully cooperating members of society over a complete life.”[25] But this does not mean that everyone has to realize these powers to the same extent in order to have an equal claim to the basic rights and liberties. [26][27]

Citizens are thus considered equal in virtue of their capacities or potential to be a certain type of person.[28] He defines this ideal of the person (as free and equal) as possessing two moral powers: the capacity for a conception of the good and the capacity for a sense of justice. The first power, falling under the power of rationality, involves the ability to formulate, prioritize, and seek to fulfill a life plan that realizes one's fundamental values and goals.[29] The second power, related to reasonableness, involves the ability to propose and abide by fair terms of cooperation, recognizing the burdens of judgment that lead to reasonable disagreement.[30] These powers are essential for social cooperation and the development of moral and rational capacities in a just society.

The thin theory of the good

Nevertheless, Rawls, too, has a conception of what is good that is applicable to all citizens. Like Plato, Rawls argues that there is a relationship between the development of citizen’s capacities, the contribution of those developed capacities to social justice, and the simultaneous contribution of those developed capacities to individual happiness.

Rawls’ conception of citizens’ needs, that of primary goods, is derived from his conception of persons as free and equal, and of society as a fair system of cooperation over time.

Primary goods are the object of rational desire, regardless of other desires or conceptions of the good life. The basic underlying thought is that a particular minimum of resources and conditions is required for the pursuit of any rational life plan (consistent with the principles of justice). Rawls stipulates that citizens have a ‘higher-order interest’ in developing the moral powers. These interests are higher-order, according to Rawls, because a failure to fulfill them prevents the achievement of particular goals or interests.[31] Therefore, he argues “primary goods are things generally required, or needed, by citizens [regarded] as free and equal moral persons who seek to advance (admissible and determinate) conceptions of the good.”[32] In contrast to preferences and desires, he states, “[c]itizens’ needs are objective in a way that desires are not; that is, they express requirements of persons with certain highest-order interests who have a certain social role and status. If these requirements are not met, persons cannot maintain their role or status, or achieve their essential aims.”[33] This claim about what citizens need, therefore, is supposed to be independent of any particular conception of the good.

However, he explicitly wants to formulate these goods independently of a particular conception of the good. He therefore invokes a theory of a person’s good that is not tied to any particular comprehensive doctrine. He calls this the thin theory of the good. According to this conception, a person’s good is determined by the plan of life that is most rational for that particular individual. [34]A rational plan of life is long-term plan which allows for the harmonious satisfaction of interests.[35] It “allows a person to flourish, as far as circumstances permit, and to exercise realized abilities as much as he can.”[36] Happiness, then, is the successful execution of that rational life plan. Flourishing does not consist only in developing one’s capacity to fulfill a socially necessary task (e.g. becoming a philosopher-king, or guardian, or producer).

Rawls postulates an account of human nature,[37] which he calls the Aristotelian Principle. This, according to Rawls, is a principle of motivation that “characterizes human beings as importantly moved not only by the pressure of bodily needs, but also by the desire to do things enjoyed imply for their own sakes, at least when the urgent and pressing wants are satisfied.”[38] The principle states that human beings enjoy exercising their realized innate abilities, and more so the more this ability is developed.

This principle is supposed to give content to the formal definition of a person’s good, because its application is “always relative to the individual and therefore to his natural assets and particular situation.”[39] It states that “we prefer, other things equal, activities that depend upon a larger repertoire of realized capacities and that are more complex.”[40]

The contrast with Plato here is that the realization of innate talents is enjoyed for its own sake, and not for its contribution to a just social arrangement. The difference here, is that citizens themselves choose which natural talents to develop, instead of the state. For Plato, not everyone has the inborn potential for rationality necessary for governance. But such a view on rationality and political authority is antithetical to Rawls’ project:

“Justice as fairness is not a maximizing theory. We are not directed to look for differences in natural features that affect some maximand and therefore serve as possible grounds for different grades of citizenship.“ [41]

Rawls states that, since the distribution of natural assets is somewhat arbitrary, they must be viewed as a “social asset to be used for the common advantage.” [42] This aim is captured in Rawls’ second principle of justice: the difference principle. This principle states that social and economic inequalities are permissible only insofar (1) they are attached to positions and offices accessible to all (fair equality of opportunity) and (2) they benefit the least advantaged.[43]

Like the Aristotelian Principle, the tripartite theory is presented to account for our desires, as well as accounting for the diversity of patterns of desire. Citizens are classified based on the dominant motivational principle in their soul (reason, spirit, or appetite). Their psychological makeup makes them particularly fit for certain types of activity.

In the case of the Aristotelian Principle, the fact that we enjoy the development and exercise of our innate abilities means that we are more inclined to do so, absent any overriding factors. But the development of excellence cannot be at the cost of society as a whole. For Plato, ‘cannot’ expresses a logical impossibility. For Rawls, ‘cannot’ expresses a moral prohibition. For the latter, justice and the good must be endorsed by those who live under it. The content of justice, the content of the good; it must all spring from the reason possessed by all who wish to live with others on fair terms. This shape of Rawls theory of justice is a reflection of its respect for an ideal of human nature.

Conclusion

Rawls aims to develop principles of justice that abstract from individual differences, while Plato builds his ideal society around the perfection of those differences. The foundational divide between the two are their standards of justification employed in their theorizing. For Rawls, the rules that govern a basic structure must be justifiable to those affected by it. However, this justifiability-to criterium only applies insofar citizens are regarded as free and equal, independently of race, sex, gender, religion, socio-economic position etc. According to Rawls, natural differences are morally arbitrary, and therefore do not merit benefits.[44] For Plato, not so. In fact, for Plato, this is inherently impossible, since the brute fact of human diversity means that not everyone is able to develop the ability to contemplate the good. Views like Plato’s, according to Rawls, “hold that institutions are justifiable to the extent that they effectively promote that good.”[45]: the, to us, absurd prescriptions of the ideal city are justified because their purpose is to ensure bringing about a certain end, namely, to create virtuous citizens that uphold perfect justice. However, Rawls valuation of the power of autonomy is what separates his conception of justice from Plato’s. Formally, both agree that justice should allow for the realization of human nature(s). But since Rawls’ modern conception of human nature contains the property of being free, he cannot accept the idea that one’s natural talents is a basis for coercively assigning social and political offices. This small difference results in a wholly different constellation of institutions which constitute perfect justice.

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———. Political Liberalism. Expanded ed. Columbia Classics in Philosophy. New York: Columbia University Press, 2005.

———. “Social Unity and Primary Goods.” In Utilitarianism and Beyond, edited by Amartya Sen and Bernard Williams, 1st ed., 159–86. Cambridge University Press, 1982. https://doi.org/10.1017/CBO9780511611964.010.

Roughley, Neil. “Human Nature.” In The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta and Uri Nodelman, Winter 2023. Metaphysics Research Lab, Stanford University, 2023. https://plato.stanford.edu/archives/win2023/entries/human-nature/.

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  1. Joel Kupperman, Theories of Human Nature (Indianapolis: Hackett Publ. Company, 2010), 3ff. ↑

  2. Alasdair C. MacIntyre, After Virtue: A Study in Moral Theory, 3rd ed (London: Bloomsbury, 2011), 65. ↑

  3. Michael J Sandel, “The Procedural Republic and the Unencumbered Self,” 1985, 82. ↑

  4. That is to say, its best possible condition, “a certain health, beauty and good condition” (444e) ↑

  5. Christine M. Korsgaard, The Sources of Normativity (Cambridge: Cambridge University Press, 1996), 3–4, https://doi.org/10.1017/CBO9780511554476. ↑

  6. Peter McNamara, “Human Nature,” in The Encyclopedia of Political Thought (John Wiley & Sons, Ltd, 2014), 1713–25, https://doi.org/10.1002/9781118474396.wbept0487. ↑

  7. M. T. McClure, “The Greek Conception of Nature,” The Philosophical Review 43, no. 2 (1934): 112, https://doi.org/10.2307/2179890. ↑

  8. Annas remarks that “function” must not be taken in the narrow sense as that by which an artefact realizes externally imposed purpose. Instead, it refers to what a thing does characteristically, qua the kind of thing it is. Julia Annas, An Introduction to Plato’s Republic, Reprinted (Oxford: Clarendon Press, 2009), 54. ↑

  9. Annas, 53. ↑

  10. Robert W. Hall, “Plato and Personhood,” The Personalist Forum 8, no. 2 (1992): 89. ↑

  11. Neil Roughley, “Human Nature,” in The Stanford Encyclopedia of Philosophy, ed. Edward N. Zalta and Uri Nodelman, Winter 2023 (Metaphysics Research Lab, Stanford University, 2023), https://plato.stanford.edu/archives/win2023/entries/human-nature/. ↑

  12. Similar conceptions of the soul were already present in the Greek culture. ↑

  13. Not to be confused with book XIII, where Socrates illustrates how each type of soul corresponds to a type of regime. ↑

  14. Those in whom the appetites rule are called money-lovers, because money is the main means for acquiring the objects of the appetites. ↑

  15. Rawls, Political Liberalism, 184. ↑

  16. Rawls, 271. ↑

  17. Rawls, xvii ff., 4. ↑

  18. I borrow this phrase from Charles Larmore, “Political Liberalism: Its Motivations and Goals” 1 (2015). ↑

  19. Rawls, Political Liberalism, 36. ↑

  20. Rawls, 134. ↑

  21. Rawls, A Theory of Justice, xviii. ↑

  22. Rawls, Political Liberalism, 32. ↑

  23. Rawls, 109. ↑

  24. Rawls, xl. ↑

  25. Rawls, 183. ↑

  26. Rawls, A Theory of Justice, 445. ↑

  27. Rawls, 444. ↑

  28. Rawls, 445. ↑

  29. Rawls, 358ff. ↑

  30. Rawls, Political Liberalism, xvi. ↑

  31. Rawls, 74. ↑

  32. John Rawls, “Social Unity and Primary Goods,” in Utilitarianism and Beyond, ed. Amartya Sen and Bernard Williams, 1st ed. (Cambridge University Press, 1982), 172, https://doi.org/10.1017/CBO9780511611964.010. ↑

  33. Rawls, 172-3 ↑

  34. Rawls, A Theory of Justice, 80. ↑

  35. Rawls, 80. ↑

  36. Rawls, 376. ↑

  37. Rawls, 379. ‘Nature’ is used here like in Plato, since it purports to explain human motivation and desire, i.e. what generally moves human beings. ↑

  38. Rawls, 379. ↑

  39. Rawls, 387. ↑

  40. Rawls, 377. ↑

  41. Rawls, 445. ↑

  42. Rawls, 92. ↑

  43. Rawls, Political Liberalism, 6. ↑

  44. John Rawls, A Theory of Justice, Rev. ed., 5.-6. printing (Cambridge, Mass: Belknap Press of Harvard Univ. Press, 1999), 447. ↑

  45. John Rawls, Political Liberalism, Expanded ed, Columbia Classics in Philosophy (New York: Columbia University Press, 2005), 134. ↑