In April, Ian Storey and I appeared on Heterodox Academy’s podcast, Half Hour of Heterodoxy, to discuss the philosophical differences between the left and right. For most of the episode, we rejected common theories that attempt to explain the left/right split. To take just one example, neither of us accepted the idea that the left is characterized by support for the big government while the right is characterized by opposition to it. Our conversation sparked a response from Hyrum Lewis, a professor of history at Brigham Young University - Idaho. Writing for Heterodox: The HxA Blog, Lewis made the case for a position that Storey and I did not consider: that the left/right spectrum does not actually exist.For Lewis, no underlying philosophy unites either the left or the right. Instead, right and left are mere tribal designations. People subscribe to a set of beliefs because they identify themselves as members of a tribe—the left-wing or right-wing tribe. Thus they support whatever policy their team happens to support at a given moment. As Lewis puts it, “if the right-wing team is currently in favor of tax cuts and opposed to abortion, then those who identify with that team will adopt those positions as a matter of social conformity, not because both are expressions of some underlying principle.”

Moreover, Lewis argues, the tribal nature of the left/right divide offers the best explanation of why political partisans can completely reverse their political positions over short periods of time. “In the past decade alone,” he writes, “we’ve seen self-described conservatives go from being anti-Russia to more pro-Russia, strongly pro-[free-]trade to strongly anti-trade, believing that personal character matters a great deal in politicians to believing that it matters hardly at all…” In Lewis’ estimation, there is no essence behind the left or the right, only tribalism.

Lewis’ theory goes wrong by conflating the left/right split with the Democrat/Republican split within the United States. Much of what he says holds for the latter divide but not for the former. So yes, it is true that no single normative principle unites all the policy positions of either the Republican or the Democratic party. Issues like abortion, tax policy, immigration, criminal justice, and environmental regulation are mostly unrelated, so believing that (say) abortion is immoral, shouldn’t commit you to believe that (say) taxes are too high. Yet as Lewis points out, people’s opinions on these issues tend to travel together, as it were. Tribalism is a good explanation for why many Americans’ constellation of policy positions often are what they are: people first come to identify with a political party and only later do they come to accept all or most of its policy positions, even when the issues themselves are orthogonal to each other.

The difference between left and right, however, is not the same thing as the division between Democrats and Republicans. Indeed, to approach the left/right split it might be best to start by wholly abstracting from political practice in order to enter the realm of political theory. In this context, political practice refers to the actions of politicians, social movements, and other political actors in the real world. Political theory, meanwhile, refers to the written or spoken articulation of political doctrines, either by writers (in their treatises) or politicians (in their speeches). Practice refers to what political actors actually do; theory refers to the normative justifications given for what ought to be done.

There is, at the level of theory, a very noticeable difference between the left and right, and that difference concerns the value of equality. The main distinction between left and right is that the left advances a politics of egalitarianism, while the right opposes the left and attempts to defend some other value—tradition, for example, or individual freedom, or public order. These, at least, are ideal-types for the left and the right, even if things look much messier in practice.

Both political camps (but especially the right) contain an impressive amount of internal philosophical diversity. Obviously not all leftists agree with each other, nor do all rightists. Yet that disagreement should not obscure their fundamental characteristic—either approval of or opposition to, egalitarianism. As Steven Lukes explains, "the project of the left can be expressed in a variety of ways—in the language of rights or of class conflict, as a story of expanding citizenship, or justice or democracy, or as a continuing struggle against exploitation and oppression; it can take any number of organizational forms…it can be elitist or democratic… reformist or revolutionary, consensus-seeking or militant, integrative or sectarian, and its constituencies can be narrowly or broadly based. But whatever its language, form, and following, it makes the assumption that there are unjustified inequalities which those on the right see as sacred or inviolable or natural or inevitable and that these should be reduced or abolished."

Consider some of the political ideologies we now refer to as leftist: socialism, radical feminism, and anti-racism. The three of them share a commitment to eradicating some system of power that is deemed to be unequal and hence unjust—respectively wealth, gender, and racial inequality.

Consider now some political ideologies we refer to as rightist or conservative: libertarianism, traditionalism, and nationalism. The first seeks to promote individual freedom and economic prosperity; the second seeks to defend tradition, piety, and social stability; the third seeks to preserve the national community. All three oppose the egalitarian projects of the left and make some value other than equality their highest value.

Of course, conservatives are not opposed to all forms of equality. Indeed, just about all contemporary political ideologies affirm some kind of equality. There now exists a broadly shared consensus that all humans are of equal moral worth, for example, which explains why there are no longer any serious arguments for slavery, a practice that obviously violates the moral worth of those enslaved. Nevertheless, as Steven Lukes argues, leftists do have a “thicker rather than thinner interpretations of the political and social ideals of equality and their redistributive and other implications for present action and policy.” Put differently, leftists derive more egalitarian policy prescriptions from their view of equality than conservatives do, even if both can agree that all humans are of equal moral worth.

It is worth repeating that this analysis of the left/right split works best at the level of theory, as an ideal-type representation of both camps. The left claims to fight on behalf of equality, while the right claims to oppose the left and fight on behalf of individual freedom, or of social order, or some other value different from equality. In practice, both sides often fail to live up to their ideals; sometimes they even betray them entirely. Nonetheless, the moral language to which the left appeals is remarkably consistent, as is that of the right. Across both time and space, leftists have sought to promote some strong version of equality, while rightists have sought to defeat the left and defend some other primary value. One is hard-pressed to find an example of a conservative movement that justifies its goals on egalitarian grounds, or of a leftist movement whose platform does not appeal principally to the moral value of equality.

This “equality theory” of the left/right split carries an implication that speaks to some of Hyrum Lewis’ concerns: namely, that the left/right spectrum does not explain all-important political debates. In other words, not all contentious issues reflect one’s underlying theory of equality; thus not all contentious issues reflect one’s conservatism or radicalism. Gun control is a good example of an issue that correlates with people’s other policy positions because of partisanship (i.e. tribalism) rather than political ideology. There is nothing conservative about opposing stricter gun control, nor anything leftist about supporting it.

So the left/right political spectrum does not explain the whole array of possible political positions—but that is no reason to dismiss it as a useless interpretative framework. No theory about the political world succeeds in perfectly capturing reality. Theories are helpful to the extent that they explain certain phenomena, and the left/right political spectrum does explain two of the main political-philosophic camps in modern history: those whose highest value is equality, and those whose highest value is both different from equality and, in their view, at odds with it.