Since 1949, job growth under Democratic presidencies has been more than twice as large as that during Republican administrations (2.47% to 1.07%). Excluding public sector jobs, the advantage is even greater (2.55% to 0.97%). Other key averages reveal a similar distinction during this period: Real business investment growth advanced 6.58% under Democratic presidents and 2.98% under their Republican counterparts; real personal income — excluding government transfers — increased 2.66% and real economic growth per capita (net domestic product) advanced 2.6% under Democratic chief executives, but only by 1.41% and 1.28%, respectively, under Republican leaders. Inflation has also been much more modest under Democratic presidents (2.91% compared to 3.28% under their Republican counterparts), with an even more decided advantage when volatile energy and food markets are excluded (2.87% compared to 3.59%).

Of the 11 U.S. recessions we’ve endured over the past 75 years, 10 began in Republican presidential administrations; only Jimmy Carter — embracing Republican-style fiscal, monetary and regulatory policy much more completely than any other recent Democratic president — presided over a “Democratic” recession. The two “double-dip” recessions of 1980 and 1981-82, straddling the late Carter and early Reagan administrations, are almost indistinguishable in their policy origins.

We are reminded consistently by pundits, journalists and scholars that tax cuts represent what may be our most readily available and useful tool for economic stimulus. Flat, or flatter, taxes, we are told, are the only means to the achievement of tax simplicity and tax compliance.

Even on the question of who tends to favor lower or higher taxes, it is easy to be deceived. When income taxes are reduced (at the federal and state level) and the entire tax code is rendered less progressive as a result, two things happen almost automatically: other much more regressive taxes rise to fill the vacuum created by universally demanded (if not readily acknowledged) public services and consumer demand falters as higher taxes begin to fall on those compelled to spend all that they earn. Overall economic activity and prospective revenue growth, in turn, begin to stagnate, triggering a vicious cycle of tax rate increases (among the untouched regressive tax vehicles), just to maintain public services and economic activity.

Republican politicians have stumbled upon a remarkably effective political strategy: preach tax cuts as the be-all and end-all of successful economic policy; ignore the ways in which federal income tax cuts often lead to increased tolls, fees and property, sales, and excise tax increases; relinquish all but rhetorical opposition to the federal deficits created by federal tax cuts; and cap it off by hinting repeatedly that more could be done — allegedly to great effect — by reducing government spending directed at “undeserving” and “unambitious” poor people of color.

Republican political leaders have their cake and eat it too, riding a diffuse anti-tax sentiment to political victory. Actual results in this game don’t often matter, at least as long as their Democratic opponents succeed in staving off the most precipitous decline with safety nets and the preservation of some progressive fiscal policy elements.

Begun quietly with what Republican activist and Wall Street Journal editor Jude Wanniski called the “Two Santa Claus Theory” — under which Republicans could counter the Democratic social spending Santa Claus with their own tax-cutting Kris Kringle — this approach promised political “success” even amid policy failure, for opponents could be pinned with the deficits and damage it produced.

Exploiting normal psychological tendencies to imagine that “more money in my pocket” and “less money in theirs” simply must be good policy, the widespread ignorance of actual public spending and significant intergovernmental fiscal policies (where federal change forces state and local change, or vice versa), and the compelling notion that personal economic opportunity or success must be derived from personal talent and initiative (rather than significant public policy reform), the “Two Santa Claus” strategy has buoyed a Republican Party that has consistently delivered sub-par results.

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.”

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.

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.

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.

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.

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.

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.

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.

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.