Introduction

The belief that all human beings are ‘moral equals’, or of ‘equal moral status or worth or standing’, is widely shared in modern Western society. This is reflected within the canon of Western liberal philosophy. For instance, Richard Arneson (2014, p. 30) states that ‘claims about basic human equality are profound and widely shared’. George Sher (2014b, p. 17) calls the contention that all human beings have equal moral standing as ‘[o]ne of the rare points of agreement’ among most moral and political philosophers. Thomas Christiano (2014, p. 53) claims that ‘[s]ome kind of equality of status among persons has been a mainstay of moral and political thought since at least the sixteenth century’.

However, it is unclear what ‘moral equality’ or its associate terms mean. The notion of ‘moral equality’, or what Christopher Nathan refers to as ‘basic equality’, ‘is usually described as a highly abstract idea’ and ‘seems elusive’ to the extent that ‘[w]e might consider it as an unhelpful concept that says nothing; an unworthy subject of inquiry’ (Nathan 2014, pp. 2–3). It has been used interchangeably with phrases such as ‘all should be treated as equals’, ‘all are due equal concern and respect’, and ‘persons have equal moral worth or status or standing’. Relatedly, Oscar Horta (2017, p. 900) defines ‘moral status’ as denoting ‘a certain attribute either possessed by, or ascribed to, some special beings, which, ceteris paribus determine that they are to be considered in certain ways, comparatively more or less favorably than other entities with different statuses’. Despite the elusiveness of these terms, Nathan (2014, p. 3) admits that these terms are ‘part of our discourse, and for this reason we ought to examine it more closely’. In this paper, I mostly use the term ‘moral equality’.

It is also unclear what grounds the ‘moral equality’ of all human beings. One of the difficulties of grounding ‘moral equality’ is how to find a property (or a set of properties) that all human beings share equally. If we try to ground ‘moral equality’ in properties that permit of different degrees of possession, e.g. sentience or cognitive capacity, the result will be that, unless it is possible to discharge of the difference in degrees for moral purposes, human beings are not ‘moral equals’. This problem seems extremely hard to resolve. Consider Sher’s (2014a) account, which Husi (2017) recognizes as ‘the arguably best attempt at a solution’. Sher (2014a, p. 80) tries to ground our ‘equal moral standing’ in subjectivity, which he understands as: ‘each occupies a point of view from which the world appears a certain way, certain things appear to matter, and certain courses of action appear to be open’ and therefore ‘any variations in the contents of our beliefs and aims, and in the capacities that gave rise to these, will simply drop out as irrelevant’. However, if subjectivity is just about having any point of view, then many intelligent animals also have their own subjectivity, thus they are also the ‘moral equals’ of human beings, a conclusion that is considered undesirable to some scholars including Arneson (2014). On the other hand, if different contents of subjectivity lead to different moral status or standing, given that different human beings almost certainly have different contents of subjectivity, all human beings almost certainly are not ‘moral equals’. In other words, attempts to ground ‘moral equality’ face the following dilemma: if you set a standard too low, this leads to the conclusion that some animals are ‘moral equals’ of human beings, which some scholars find undesirable; if you set a standard too high, you risk leading to another undesirable conclusion that some human beings are not ‘moral equals’ of others.

It is further unclear what the implications of the ‘moral equality’ of human beings are. The idea of abstract equality is often alleged to inform concrete egalitarian requirements, such as equal rights or distribution. For instance, Arneson (2013, para. 1) states that equal fundamental worth or moral status is a background idea that egalitarian doctrines tend to rest on. Jeremy Waldron (2011, p. 4) also says that ‘propositions about status expressive of the idea of basic equality—especially propositions about single-status—play an important role in generating moral conclusions’. However, different egalitarian doctrines place different weights on the role and importance of equality and have different criteria for what amount to permissible deviation from equality. It is unclear what exactly human beings are entitled to equally due to their ‘moral equality’.

In this paper, I explore the relations between descriptive properties that might be thought to ground our ‘moral equality’,Footnote 1 the status of being ‘moral equals’, and the reasons that we have for behaving in certain ways with regard to beings that are ‘moral equals’. I distinguish between three ways of understanding ‘moral equality’: the ‘buck-passing’, ‘explanatory’ and ‘reverse-explanatory’ accounts. The buck-passing account of moral equality is in parallel with Scanlon’s buck-passing account of value. It holds that ‘moral equality’ is not a metaphysically fundamental concept and simply amounts to having other properties shared equally by all human beings that constitute the reasons for why we ought to treat all human beings equally in certain respects. The explanatory account understands the concept of ‘moral equality’ as metaphysically fundamental and capable of illustrating why human beings who are the same in certain respects have the same entitlement to x. The reverse-explanatory account also sees ‘moral equality’ as metaphysically fundamental but holds that the explanatory relationship goes the other way round: moral equality is explained by how we ought to act. I argue that the buck-passing account is a more accurate way of understanding moral equality.

In what follows, I first set out the three conceptions of ‘moral equality’. Then, partly deriving from Peter Westen’s critique of equality, I establish five criteria for a successful account of moral equality. Next, I argue for the buck-passing account of moral equality. I also rebut the two alternative accounts: the explanatory and reverse-explanatory accounts. Finally, I take stock and explain the implications of my arguments.

Three Conceptions of ‘Moral Equality’

This section sets out three different conceptions of moral equality, which form the subject of analysis of this paper. To attain a better understanding of moral equality, one needs to analyze the relations between descriptive properties that partly ground our ‘moral equality’, the status of being ‘moral equals’, and the reasons that we have for behaving in certain ways with regard to beings that are ‘moral equals’. Understanding how these three items relate to one another allows me to distinguish between the three conceptions of moral equality, which I refer to as the ‘buck-passing’, ‘explanatory’ and ‘reverse-explanatory’ accounts.

First, I observe an interesting parallel between this issue and Thomas Scanlon’s buck-passing account of value. Scanlon (1998, p. 97) investigates the relationship between the natural (or what I call ‘descriptive’) properties of a thing, the property of being valuable, and our reasons to behave or react in certain ways with regard to things that are valuable. Scanlon (1998, p. 97) observes that there are at least two ways of characterizing the relationship: one is that those natural property ground a derivative property of ‘being valuable’ that attaches to the thing in question, whilst the other is that those initial properties act as reasons for behaving in certain ways, thereby partly constituting the value of their object. To quote:

The first [account of the relevant relationship] is that when something has the right natural properties it has the further property of being valuable, and that property gives us reason to behave or react in certain ways with regard to it. Moore seems to be taking this view about goodness when he says that it is a simple, unanalyzable, non-natural property. The alternative, which I believe to be correct, is to hold that being good, or valuable, is not a property that itself provides a reason to respond to a thing in certain ways. Rather, to be good or valuable is to have other properties that constitute such reasons…It differs from the first alternative simply in holding that it is not goodness or value itself that provides reasons but rather other properties that do so. For this reason I call it a buck-passing account. (Scanlon 1998, p. 97, emphasis added)

I distinguish between three ways of understanding moral equality, based on the relations between descriptive properties that partly ground our ‘moral equality’, the status of being ‘moral equals’, and the reasons that we have for behaving in certain ways with regard to beings that are ‘moral equals’. The ‘buck-passing’ account holds that to be ‘moral equals’ is to have other properties shared equally by human beings that constitute the reasons for why we, prima facie, ought to treat human beings equally in some respect x. It is the other properties, i.e. human beings are the same in certain respects, that provide a full explanation of why we, prima facie, ought to treat them equally in some respect x. Thus understood, moral equality is not a metaphysically fundamental property: it merely points to the descriptive properties that provide reasons for actions. The explanatory account understands ‘moral equality’ as being metaphysically fundamental: it illuminates why human beings who possess certain descriptive properties equally, prima facie, ought to be treated equally in some respect x. Thus understood, moral equality cannot simply consist in our possession of certain equal descriptive properties or our equal moral entitlement; it must be characterized independently. The reverse-explanatory account agrees with the explanatory account that moral equality is metaphysically fundamental but argues that the explanatory relationship is the other way around: how we ought to treat certain beings explains why, and in what ways, such beings are moral equals. Thus understood, moral equality merely is the ‘outcome’ of the moral evaluation of a being.

In what follows, I first establish five criteria for a successful account of equality. Then, I argue for the buck-passing account of moral equality. After that, I argue why the explanatory account and the reverse-explanatory account suffer from some significant difficulties that are not present in the buck-passing account.

Five Criteria for a Successful Account of Moral Equality

In this section, I establish five criteria for a successful account of moral equality: (i) it identifies the morally relevant descriptive facts that hold true in relation to human beings; (ii) it ascertains the relevant basic norms; (iii) it ascertains the concrete moral implications that follow in relation to actual human behavior; (iv) it explains why moral equality appears to be explanatory (regardless of whether it actually is explanatory); (v) it does not support ‘leveling down’. These five criteria form the basis of evaluating the three conceptions of moral equality.

First, I establish criteria (i) to (iii) with reference to Peter Westen’s tautology charge against the principle of equality, which he takes to proclaim that ‘people who are alike should be treated alike’.Footnote 2 Westen’s (1982, p. 547) argument—that this principle is tautologous, and therefore analytically suspect—has two stages. First, he observes the logical difficulty of moving from descriptive facts (‘people who are alike’) to normative statements (‘ought to be treated alike’). This leads him to argue that no sensible interpretation of the principle of equality could entail such a move: given that human beings cannot be alike in every respect, and that all things are alike in some respect, the only reasonable way to understand ‘people who are alike’ is to assume that it refers to ‘a normative determination that two people are alike in a morally significant respect’ (Westen 1982, pp. 539, 544, and 545). In other words, the first half of the formula already incorporates a normative element, and when it moves to the conclusion that ‘people should be treated alike’, it merely ‘derives an “ought” from an “ought”’; i.e. moves from norm to norm (Westen 1982, p. 545). Based on this conclusion, the second stage of Westen’s argument contends that the same moral standard that determines the descriptive properties in relation to which human beings should be considered ‘alike’ also determines that they ought to be treated ‘alike’. As such, so his argument goes, the principle of equality becomes tautologous (Westen 1982, p. 547).

The takeaway from Westen’s argument is that we ought to discover specific descriptive facts that, when used in conjunction with certain basic norms (e.g. ‘we ought not to harm’), can create specific moral principles that tell you how you ought to act. For instance, assume that all human beings have roughly comparable susceptibility to pain. This assumption, when combined with the general norm ‘prima facie, we ought not cause pain to those who can feel it’, would create the specific moral principle ‘prima facie, we equally ought not inflict pain on any human being’. Therefore, the first part of the equation (‘people who are alike’), specific morally relevant descriptive facts, together with an abstract norm, jointly entail a specific moral principle that tells you how human beings ought to be treated: ‘people should be treated alike’. This establishes the first three criteria for a successful account of moral equality: (i) it identifies the morally relevant descriptive facts that hold true in relation to human beings; (ii) it ascertains the relevant basic norms; (iii) it ascertains the concrete moral implications that follow in relation to actual human behavior.

Here, I would also like to add two further criteria. The fourth criterion states that it must explain why moral equality appears to be explanatory (regardless of whether it actually is explanatory). It is because moral equality is typically taken to be explanatory in the extant literature. For instance, Waldron (2011, p. 4) claims that ‘propositions about status expressive of the idea of basic equality—especially propositions about single-status—play an important role in generating moral conclusions’. Similarly, Husi (2017, p. 387) argues that ‘[t]he notion of moral status is clearly devised to play an important justificatory role, to make a genuine moral difference’. He further elaborates on this justificatory role, as follows: ‘[t]here is the immensely plausible thought that it is in virtue of certain mental and agential capacities that people are to be treated differently than rocks and trees, and it is fair to ask how to spell out this thought without running into something equivalent to moral status’ (Husi 2017, p. 387). Given that moral equality is understood as having an explanatory role, a good account of moral equality needs to either grant it such a role or explain why it appears to be explanatory despite the actual absence of any explanatory functions.

The fifth criterion states that a successful account of moral equality should not be used to support ‘leveling down’, that is, equality should not be achieved by making people worse off. The leveling down objection states that equality should not be what we aim for. Rather, what really matters is whether our rights and freedoms are protected. If equality is achieved by depriving the well-off of their rights and freedoms, so that they become ‘equals’ of the less well-off, then equality is not a goal worthy of pursuit. Since leveling down is a morally undesirable outcome, advocates of equality must show that their accounts are not vulnerable to the leveling down objection.

To sum up, the five criteria for a successful account of moral equality are: (i) it identifies the morally relevant descriptive facts that hold true in relation to human beings; (ii) it ascertains the relevant basic norms; (iii) it ascertains the concrete moral implications that follow in relation to actual human behavior; (iv) it explains why moral equality appears to be explanatory (regardless of whether it actually is explanatory); (v) it does not support ‘leveling down’. In the following sections, I apply the five criteria to the three conceptions of moral equality.

A Buck-Passing Account of Moral Equality

In this section, I argue for a buck-passing account of moral equality, which states that: ‘there are descriptive properties, shared equally by all human beings, that provide reasons why we, prima facie, ought to treat all human beings equally in certain respects’ (hereinafter p). To claim that human beings are moral equals is merely an easier way of saying p. Moral equality is not a metaphysically fundamental concept. It only has an apparently important explanatory role in the following sense: it refers to descriptive properties that have an explanatory role, so ‘absorbs’ the explanatory role of the referent (descriptive properties).

First, the buck-passing account satisfies the five criteria identified in the last section. It satisfies criteria (i) and (iii) because it points directly to the morally relevant descriptive facts and concrete moral implications. It can satisfy criterion (ii) because it requires the existence of basic norms that identify which descriptive facts are morally relevant. It satisfies criterion (iv) because moral equality points to the descriptive facts that are explanatory of the moral implications. This leaves the impression that moral equality is explanatory. It satisfies criterion (v) because the basic norms identify which kind of descriptive facts have which kind of moral implication; equality has no role in it.

Second, the buck-passing account supports the plurality of moral reasoning. By the plurality of moral reasoning, I mean that, depending on the context, many different descriptive properties that we share can be used to, pro tanto, ground our moral entitlements. For instance, if the context is education rights, that we are within a certain range of intellectual ability can be used to, pro tanto, ground our equal right in receiving education until a certain age or level, and in this sense, we are ‘moral equals’. If the context is rights to healthcare, then our similar interests in having access to proper healthcare can be used to, pro tanto, ground our equal right to access of healthcare service, and in this other sense, we are ‘moral equals’. We may rely on yet another set of descriptive properties to decide who is to be granted a voice in public policy decisions.Footnote 3 For instance, if the context is a change in taxation policy, those who pay tax or have an interest in policies funded by taxation should have a voice in deciding the new taxation policy, and in this sense, we are again ‘moral equals’. Therefore, if you believe that substantive and procedural rights should be justified by a variety of morally relevant descriptive properties, this is a reason to support understanding moral equality as a metaphysically non-fundamental property that merely acts as the shorthand of different morally relevant descriptive properties.

On the other hand, if moral equality is metaphysically fundamental as the explanatory account claims, it is misleading to divide all beings binarily into two moral categories: ‘moral equals’ or ‘not moral equals’. It is misleading because it assumes that there is a single, universal way of ranking all beings and putting them into the respective moral categories that will be used to determine their moral entitlements. Since different morally relevant descriptive properties support different concrete moral implications, it is highly unlikely that we can achieve a neat binary categorization of all beings. Instead, we will have a messy categorization: for instance, person 1 and person 2 are moral equals in the ‘right to healthcare’ aspect if both persons have an interest in having good health, but not moral equals in the ‘right from imprisonment’ aspect if person 1 breaks the law. There is little point in asking whether the two persons are all-things-considered ‘moral equals’, because this will not affect their equal right to healthcare nor unequal right from imprisonment. It is unclear what explanatory role this all-things-considered moral equality plays when deciding specific moral entitlements.

Moreover, the buck-passing account is explanatory parsimony: fewer assumptions are required to get to the same conclusions about the concrete moral implications. Consider my right to basic subsistence: most would agree that my interest in being alive grounds my right to basic subsistence. Of course, one may further assume that I have a moral status that also underlies my right to basic subsistence; or that I am of moral worth, a necessary precondition for enjoying a right to basic subsistence; or that I am owed moral respect, the fulfillment of which requires me to enjoy a further right to basic subsistence. However, one can reach the same conclusion that I have a right to basic subsistence simply by appealing to my interest in being alive and a basic norm that connects human rights with human interests (e.g. an interest theory of human rights that grounds human rights in sufficiently important human interests), without additional assumptions about moral status, moral worth, and moral respect. As such, the buck-passing account has the advantages of simplicity and elegance.

Furthermore, the buck-passing account sits well with the long tradition of grounding human rights in some specific descriptive properties. If you endorse the interest theory of human rights, you are committed to grounding rights in some sufficiently important human interests (Raz 1986). If you endorse the will theory of human rights, you are committed to grounding rights in how they protect the freedom of will (Cruft 2004). The relevant descriptive properties—be it the sufficiently important human interests or the extent of the protection of the freedom of will—exhaust the reasons as to why the subject has rights. As such, under traditional human rights theories, there is no additional explanatory role that needs to be filled by calling two beings ‘moral equals’. Instead, the inherently comparative aspect of ‘moral equality’ does not sit with traditional human rights theories, which see human rights as being grounded in properties that are not inherently comparative.

To complete my argument, I consider below two situations by which moral equality might be considered to have some intrinsic reason-giving characteristics.Footnote 4 I argue that, even in those situations, moral equality is not metaphysically fundamental. The first objection states that moral equality becomes important in Western political thought as a response to feudalism, racism, slavery, patriarchy, and other forms of subjugation and oppression based on (mainly) ascriptive characteristics. Those adopting this point of view ask how one can explain the wrongfulness of such practices without appealing to our moral equality. If there is no satisfactory explanation, this shows that there is some ‘residue value’ of moral equality: it explains why acts of subjugation and oppression are wrong.

Despite the intuitive appeal of explaining the wrongfulness of subjugation and oppression in the moral equality of human beings, I argue that the better explanation is that subjugation and oppression violate the value of personal autonomy. Personal autonomy is ‘an idea that is generally understood to refer to the capacity to be one’s own person, to live one’s life according to reasons and motives that are taken as one’s own and not the product of manipulative or distorting external forces’ (Christman 2018). It is valuable because a ‘peculiarly human way of experiencing and conceptualizing the world’ requires ‘self-decision’ of ‘a normative agent’: one needs to decide ‘for oneself what is worth doing’ (Griffin 2008, pp. 35, 150). To be autonomous, one needs to satisfy three conditions: (a) one must have the requisite mental capabilities; (b) one must enjoy an adequate range of options; and (c) one must enjoy independence, that is, one is free from coercion and manipulation (Raz 1986). Those who are considered ‘inferior’ are often exploited, have few rights and freedoms, have limited control over their life options, and are therefore incapable of living a prosperous and autonomous life. Consider slavery: the slave is deprived of the opportunity to take control of his/her life; his/her options are narrowed down to doing what the master permits him/her to do. Furthermore, oppression and subjugation treat the oppressed/subjugated merely as a means, without respect and without due consideration of his/her interests. The oppressor exploits the vulnerability of the oppressed, makes him/her act in a way that is against his/her own interests. Such acts are morally wrong regardless of whether the oppressed has the capacities for autonomy. The wrongfulness of exploiting others’ vulnerability also does not depend on whether the oppressed are our ‘moral equals’: exploiting the vulnerability of non-human animals is also morally wrong even if non-human animals are not our ‘moral equals’.

The second objection states that moral equality is necessary for explaining the moral difference between human beings and sentient non-human animals. There are worries that, by underplaying moral equality, the buck-passing account faces difficulties in comparing the interests of sentient non-human animals and human beings. Specifically, opponents argue that the buck-passing account leads us to the dilemma that, either one must believe that there is no difference; or if there is a difference between human beings and non-human animals on the basis of some properties held by human beings but not by animals, then such properties also serve as the basis for distinguishing among human beings.

In response, I argue that non-buck-passing accounts of moral equality would also face the same dilemma, so it is not a reason to favor non-buck-passing accounts over buck-passing accounts. Non-buck-passing accounts face the same dilemma because any successful account of moral equality must specify what grounds the moral equality of all human beings, as well as what grounds the inferior moral status of sentient non-human animals. This means that proponents of non-buck-passing accounts still need to identify descriptive properties that differentiate human beings from non-human animals without distinguishing among human beings. This leads to the same dilemma that buck-passing accounts face: it is just passed to an earlier stage when deciding whether all human beings are moral equals or whether some sentient non-human animals are moral equals of human beings.

Recognizing this problem, proponents of non-buck-passing accounts introduce the range property argument to differentiate human beings from non-human animals without differentiating among human beings. Recently, Jeremy Waldron has provided one of the richest non-buck-passing accounts and I use it to illustrate why the dilemma is also present in non-buck-passing accounts. Specifically, Waldron’s account belongs to the explanatory account because he argues that ‘propositions about status expressive of the idea of basic equality—especially propositions about single-status—play an important role in generating moral conclusions’ (Waldron 2011, p. 4). Like many others, Waldron believes in the basic equality of all human beings and searches for descriptive properties to ground this basic equality. He identifies free will, which he defines as ‘our world-making capacity to choose which of several possible worlds will be actuated by our decisions’, ‘Hannah Arendt’s theme of natality’, and ‘the aspiration to love and serve God’ (Waldron 2017, pp. 111–112). Noting that the candidate properties ‘are all capabilities humans appear to possess in different degrees’, he argues that this scale admits certain categories that constitute range properties (Waldron 2017, p. 113, emphasis in original). To illustrate the range property argument, he adopts the analogy of being in Scotland: Stirling (situated near the center of Scotland) and Gretna Green (a little village just over the border from England) are both equally in Scotland and subject to Scottish jurisdiction, despite their geographical differences (Waldron 2017, pp. 119, 222, and 223). He argues that we can ‘say that scalar differences in the degree of our intelligence or differences in the quality of various individuals’ moral decision making are eclipsed by a focus on some underlying range property of rational or moral capability … provided we motivate the focus on the range rather than on the detailed differences of degree’ (Waldron 2017, p. 223, emphasis in original).

Despite the intuitive appeal that Waldron’s position might be considered to have, his arguments also suffer from the same dilemma regarding the comparative interests of human beings and non-human animals. The problem of the range property argument goes as follows: both the upper and lower thresholds (which together make up the range) exist at least partly because of the scalar property that allows the drawing of the thresholds, making the scalar property the most fundamental matter. This does not entail that the scalar property is, for all purposes, more important; but it implies that there are some scenarios where we ought to refer to the scalar property to make the ultimate decision as to how we ought to act. For instance, all other things being equal, the difference in the descriptive property matters when deciding who ought to be entitled to a specific moral right when rights conflict. Consider the following analogy: think about the academic standing of four students: Student 1 is near the upper threshold of first-class honor; Student 2 is just above the lower threshold of first-class honor; Student 3 obtains second-class honor; and Student 4 obtains third-class honor. It does not seem correct to say that Student 1 is equally as good as Student 2 in terms of academic standing, even though both students obtain first-class honor. The reason is that the GPA that determines the academic status is the more fundamental matter, and the honor classification merely illustrates the results in a standard format. The difference between Student 1’s and Student 2’s GPA still matters when deciding how we ought to treat the two students. For instance, when they compete for a competitive academic scholarship, assuming they score the same in all other aspects, Student 2 should get the scholarship. Certainly, there are cases where the difference does not matter: for instance, if an MA program admits all students who obtain first-class honor and does not admit anyone who fails to obtain first-class honor, then the difference in GPA between Student 1 and Student 2 no longer matters. But here, the reason why the difference does not matter is that both students meet a distinctive criterion for admission—they might be considered ‘equally’ qualified under that distinctive criteria; whereas Student 3 and Student 4 are ‘equally’ unqualified under that distinctive criteria. So, the issue here is not whether the difference in the more fundamental scalar property always matters, but that whether it can matter when it comes to determining the concrete implications of academic status.Footnote 5

Therefore, I concur with Arneson (2014) and Steinhoff (2014) that, considering the diversity among human beings in our current world, it is almost certainly impossible to find equal descriptive properties shared by all human beings but not non-human animals to ground the moral equality of all and only human beings. Lastly, I believe that one must choose between one of the following two options when responding to the dilemma. The first option is to endorse speciesism: being a member of the human species is a morally relevant reason for prioritizing the interests of human beings. The second option is to accept the first horn of the dilemma: there should not be any moral difference between the interests of sentient non-human animals and human beings; our partiality to our own species is morally unjustified. In any case, the choice between the two possibilities shall not matter for the purpose of this paper as the dilemma is not unique to the buck-passing account of moral equality.

In the next two sections, I challenge two alternative accounts of moral equality: an explanatory account and a reverse-explanatory account. Specifically, I argue that both accounts suffer from some further significant difficulties that are not present in the buck-passing account.

An Explanatory Account of Moral Equality

The first alternative account is an explanatory account of moral equality. It claims that appealing to ‘(un)equal moral status’ of all human beings helps explain why human beings who possess certain descriptive properties (un)equally, prima facie, ought to be treated (un)equally in some respect. Moral equality is a metaphysically fundamental concept and is necessary for prescribing moral treatments. Therefore, in addition to the five criteria identified above, proponents of the explanatory account must also show that moral equality can be characterized independently from the descriptive properties shared equally by all human beings and the normative implications (criterion (vi)).

The explanatory account can be further divided into two sub-categories. The first sub-category sees a parallel between ‘moral equality’ and Moore’s characterization of ‘good’: proponents see ‘moral equality’ as a simple, unanalyzable, non-natural property. This satisfies criterion (vi), that ‘moral equality’ can be characterized independently from the properties shared equally by all human beings. However, characterizing ‘moral equality’ as a simple and unanalyzable property makes it hard to satisfy the criterion (i): it must identify the specific morally relevant descriptive facts that hold true in relation to human beings. It also fails to satisfy criterion (iii): the normative implications of moral equality must be demonstrable and specific. This makes the first sub-category of the explanatory account vulnerable to Westen’s tautology charge: that we ought to treat all human beings as equals only because we are already determined to see them as moral equals.

The second sub-category identifies specific descriptive properties that with the assistance of the concept of moral equality can lead to concrete normative implications.Footnote 6 This means that, when human beings have the right descriptive properties, they have the further property of being ‘moral equals’ with some appropriate class of others. If specific descriptive properties that support specific moral implications are found, criteria (i) and (iii) are satisfied. However, it then becomes unclear how moral equality can be characterized independently from those specific descriptive properties shared equally by human beings. Instead, it seems that all the work is done by the specific descriptive properties. In other words, it has difficulties satisfying criterion (vi). Therefore, the explanatory account faces a dilemma: if one characterizes moral equality independently, separated from specific descriptive properties, it cannot prescribe demonstrable and specific morally correct actions. On the other hand, if one characterizes moral equality with close linkage to specific descriptive properties, it is hard to characterize moral equality independently.

Furthermore, both categories under the explanatory account have difficulties satisfying criteria (v): it does not support leveling down. The explanatory account sees ‘moral equality’ as explaining our moral entitlement, but ‘moral equality’ is an inherently comparative, binary property that divides all beings into ‘moral equals’ or ‘not moral equals’. It is only capable of prescribing ‘equal’ or ‘unequal’ treatment, not specific substantial treatment. However, equality can be achieved by everyone being worse off. Without appealing to additional normative principles that are not inherently comparative, the explanatory account becomes vulnerable to the leveling down objection.

A Reverse-explanatory Account of Moral Equality

The second alternative account is a reverse-explanatory account of moral equality. Similar to the explanatory account, the reverse-explanatory account sees moral equality as a metaphysically fundamental concept. However, unlike the explanatory account, the reverse-explanatory account believes that moral equality cannot explain how we ought to treat certain beings. Rather, the explanatory relationship is the other way around: how we ought to treat certain beings explains why, and in what ways, such beings are ‘moral equals’.

According to the reverse-explanatory account, moral (in)equality is the ‘outcome’ of moral evaluation of the being and it does not have any explanatory power. If we ought to treat all human beings equally in a certain way, this shows that all human beings are ‘moral equals’. On the other hand, if there is no dimension by which we ought to treat all human beings equally, then this shows that human beings are not ‘moral equals’. For instance, Uwe Steinhoff (2014, p. 151, emphasis in original) discusses an account of how ‘moral standing’ does not justify the granting of a moral right, but the other way round: ‘[p]eople have the same moral rights and that is what gives them equal moral standing’.Footnote 7 Here, ‘moral standing’ is measured by the actual instances of ‘moral rights’ you enjoy, so enjoying the same moral rights gives human beings ‘equal moral standing’ and vice versa. Steinhoff then rejects the idea that we have equal special rights using the right of self-defense as an example: Only Jill, the victim, but not Bill, the attacker, has the right to defend herself with lethal means at time t. Therefore, Jill has more rights, and thus higher ‘moral standing’ than Bill, at time t. The account Steinhoff discusses also illustrates a characteristic shared by the explanatory and reverse-explanatory accounts: given the diversity among human beings, both accounts may support the conclusion that we are not moral equals.Footnote 8

However, the reverse-explanatory account suffers from three difficulties. First, it fails to satisfy criterion (iv): it explains why moral equality appears to be explanatory (regardless of whether it actually is explanatory). Under the reverse-explanatory account, moral equality becomes the ‘outcome’ of moral evaluation and there is nothing that can be or might be perceived to be explained by it.

Second, understanding moral (in)equality as merely the ‘outcome’ of moral evaluation strips moral (in)equality from serving any purposes. Thus understood, moral (in)equality serves no moral purposes because, unlike the explanatory account, it does not support any concrete moral implications, i.e. it also fails to satisfy criterion (iii): it must ascertain the concrete moral implications that follow in relation to actual human behavior. It also serves no linguistical purposes because, unlike the buck-passing account, moral equality is not an easier way of stating the clumsy sentence: ‘there are descriptive properties, shared equally by all human beings, that provide reasons why we, prima facie, ought to treat all human beings equally in certain respects’. Therefore, it seems unnecessary to create the concept of moral equality just to evaluate human beings from an abstract angle.

Third, and specific to the account Steinhoff discusses, the problem of understanding ‘moral standing’ as proportional to the instances of moral rights of a human being is that it does not sit well with the common perception and use of the term. Say Will, a third party, is also at the scene. Will has a special power of incapacitating a human being in a split second with a 100% success rate. Will would have a right to incapacitate Bill but not to kill him (since killing is not a necessary response in light of Will’s special power). Note that Jill has both the right to kill Bill and the right to incapacitate him; she may defend herself in any way so long as it is a necessary and proportionate response to the threat. Now, Jill has more special rights than Will. But it would be absurd to call this higher ‘moral standing’, as it would de facto mean that Jill has higher moral standing than Will because she does not know how to incapacitate a human being without killing him (making killing a necessary response). It would also be absurd to say that, all else being equal, an innocent human being who is always subject to attack (thus has enjoyed special rights of self-defense many times) has higher ‘moral standing’ than another innocent human being who has never been subject to attack (thus never actually enjoy any special right of self-defense). Therefore, to consider the ‘moral standing’ of human beings as proportional to the instances of special rights they enjoy seems not to sit well with our usual understanding of the concept; rather, it seems like an absurd redefinition of the term.

Concluding Remark and Implications

In this paper, I have explored the relations between properties that ground our moral equality, the property of being moral equals, and the reasons that we have for behaving in certain ways with regard to beings that are moral equals. I have argued for a buck-passing account of moral equality: to be moral equals is to have other properties shared equally by all human beings that constitute the reasons for why we ought to treat all human beings equally in certain respects. I have also challenged two alternative accounts: (i) the explanatory account that sees moral equality as explaining why we ought to act in certain ways; and (ii) the reverse-explanatory account that sees moral equality as being explained by how we ought to act.

The conceptual implication of my paper is that moral equality becomes metaphysically non-fundamental. This does not render ‘moral equality’ meaningless or trivial; a term is meaningless if it is empty and tells you nothing. My point is not that ‘moral equality’ tells you nothing but that it tells you nothing new.Footnote 9 Moral equality can still tell you something, i.e. whatever we are using the term to replicate. But a replication of something is not something new, in the sense that it does not add any extra element to the thing it replicates; it cannot provide any additional support for specific equal treatments.

There is a further moral implication if the buck-passing account of moral equality succeeds. Moral equality is often used to provide support for specific entitlements or rights (or broadly speaking, deontic notions as to how we ought to act) that involve some form of equality. However, if the buck-passing account holds true, moral equality merely replicates that some descriptive properties provide the foundation for how we ought to act. Yet, the turn to moral equality somehow appears to enrich the argument: it seems to bring the discussion up to a more philosophical and foundational level. It leaves the opposite side with an uncomfortable position of having to argue against this widely shared norm of moral equality. In this sense, the reference to moral equality is deceptive: although the turn to moral (in)equality appears to be a separate step in support of (anti-)egalitarianism, it does not give you any distinctive reasons and merely acts as a smokescreen appearing to be so. Therefore, instead of debating on whether human beings are ‘moral equals’ and why, it is much more practical to directly ascertain the specific moral implications that flow from morally relevant descriptive properties with that human beings share.