What is a political party? James Campbell explores our politics’ characteristic dividedness in an excellent new book, starkly titled Polarized, that deserves to be read widely and carefully.

Campbell, who teaches political science at the University of Buffalo, is not a theorist, at least not overtly, but to see what is at stake, as well as to appreciate the new (or rather, old) path he opens up, one may begin from the theoretical viewpoint he challenges. Since the 1950s political scientists have worked within a distinction between interests and opinions, and with an emphasis on the former. Interests, they claimed, are mostly economic, hence narrow, hence definable as causes of behavior: you vote as you do because of your interest. By contrast, opinions are political, hence broad, hence vague, hence not definable as causes of the sort that produce effects. Opinions are what people say, whereas interests are the motives that prompt them to act, and also to speak, in order to express or conceal their interests. Political scientists have by and large thought that interests are more reliable, because less deceptive, than opinions. To understand interests one must learn to deprecate, even ignore, opinions, for it is often in your interest to disguise your interest as a high-minded opinion. By focusing on interests, political science as it’s been practiced for the past century has minimized the enthusiasm and zeal of partisans, failing to make real sense of their excited excesses. The study of opinions, however, allows partisans to explain themselves by taking seriously the human desire to rise above one’s selfish interest—taking charge of oneself as a free agent instead of being defined by some outside observer or partisan opponent.

The sensible course would be to say that in politics people are sometimes motivated by principle, sometimes by interest; they are inconsistent. And if this is so, perhaps the difference between interest and principle is not so clear as those who act from either motive believe it to be. Once you start explaining partisan politics with one, it seems arbitrary to shift to the other. My late colleague Richard Neustadt, a canny student of parties, once complained in my hearing of an incident with an exit pollster who questioned him after he had voted. Why had he voted as he did? His response was “Because I’m a Democrat.” The pollster looked at her clipboard for this category of explanation and did not find it. Neustadt in his answer was speaking not only as a professor looking at people’s interests but also as a voter looking to defend himself and dignify his opinion.

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A quick look at the political science literature since the 1950s will help explain the issue. The maestro of political parties in those days, V.O. Key, used both interests and opinions to develop his undogmatic insights, in some ways still unsurpassed, in his major work Southern Politics in State and Nation (1949), contrasting Southern politics with the rest of the country. A decade later a collaborative landmark study by Angus Campbell, Philip Converse, Warren Miller, and Donald Stokes appeared, The American Voter (1960), more strictly “behavioral” (poli sci lingo for more quantifiable, predictable outcomes) than Key’s work, and more reliant on the concept of interest. In between, Anthony Downs had published An Economic Theory of Democracy (1957), which carried that concept back to its origin in economics and, by reducing opinions to interests, attempted to invest the study of parties with the greater rigor that attends the dismal science.

Downs’s book is the work of a man who wanted to lift the homo economicus from the status of straw man to actual life. It is still well-known today for its compact analysis of “the median voter,” which would feature in The American Voter, but it has more readers than fans for its insistence on the simplification of politics that results from focusing on interests. In Downs’s theory the median voter is the one between the parties who likes to think himself “independent” and is in fact probably merely apathetic or ignorant or both. Since neither party can be sure that its particular coalition of interests will gain a majority, it must turn to the center to gain votes, and the median voter becomes the center of attention for both sides. This logic is “economic” in character even though it applies to parties of principle as well as, and actually more than, those of interest. Downs shows that even zealous partisans of principle have an interest in calculating by interest—which is good because it keeps principled parties moderate.

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Using Downs’s theory, however, one would expect black citizens in America to vote roughly equally for the Democrats and the Republicans so as to gain the benefits that accrue to the median voter who will be courted by both sides. Unfortunately, black voters today are roughly 90% Democratic, quite regardless of Downs. One can try to resolve this difficulty in the manner of rational choice theory, which is generally based on what is rational for one’s interest but extends one’s interest to one’s principle, for example, in the case of blacks to stand together as a community. Perhaps it is not necessary to decide whether this is their interest or their principle. But then one loses the nobility of principle as well as the exactness of interest, each spoiling the other in the observer’s sensibly moderate mix of motives. One cannot condemn blacks for their irrationality of opinion, nor praise them for their calculation of interest.

Today we find political scientists in this general situation of methodological unease, unwilling either to look beneath the surface of political opinion like a cynic or to take it seriously at face value like (what they think is) a fool. Nor does the straddle position of foolish cynic or cynical fool seem attractive. If one looks to the outstanding fact of parties today, it is certainly polarization. Polarization, it is generally agreed, means that the pull of interest toward the center, where the median voter resides, has been replaced by the attraction of principle to the steamy extremes, where zeal rather than interest prevails. Most political scientists prefer interest over principle partly because interest is more moderate and partly because it is more scientifically predictable—and they do not like polarized parties (on principle). Those on the Left favor their principle but not principle as such, and they tend to blame the reactionary Right for the polarization that results when the innocent Left has to defend itself.

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Two sage authorities now alive and active remain to be examined before we come to James Campbell. One is John Aldrich, author of Why Parties? (1995), the most prominent text in the field. Aldrich is a follower of the rational choice “formal theory,” which develops Downs’s theory of economic interest so as to determine the path of rational pursuit of one’s interest, regardless of its content. Formal theory emphasizes choice (easy to assume) rather than utility (too hard to define); it liberates the political scientist from rank utilitarianism at the cost of muddying the causal determination that arises from knowing what your true interest is. Aldrich takes the moderate, sensible position that some behavior is determined by interest, some by principle. But to do this he combines them promiscuously, apparently forgetting that they are supposed to be opposed: an action done on principle is not done by, or for, one’s interest, and vice versa.

To explain the function parties perform, he studies party history in America because Americans had to discover that function; it wasn’t so clearly in their interest as to come spontaneously. They also had to discover that two parties were better than one, moving from Thomas Jefferson’s insistence on a single true party of republicanism to Martin Van Buren’s admission that this party was not so true that it could not tolerate—and the country profit from—an opposition party. Aldrich’s resort to party history implies that a pluralist principle had over time to be accepted, as opposed to merely pursuing one’s interest regardless of partisan principle.

Yet in the book’s title and beginning chapters he remains faithful to the rational choice theory according to which collective action is the focus of attention. The title’s question mark asks whether or not collective action is in one’s interest as an individual; for Aldrich, the individual and his interest are the foundation from which to begin. The kind or character of a party is less important than the very existence of a party, which poses the prime question of whether one’s interest as an isolated individual is to cooperate with others or take advantage of them. It is noteworthy that the concept of interest, which is intended from the first and above all to avoid the partisan disputation of political opinion, cannot resolve the simplest question of whether political action is in your interest.

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With our current polarization of the parties, however, the focus of the rational choice school on collective action as such seems quite inapt. Today we find it all too easy to collectivize as Republicans or Democrats; the problem is rather that our collective action is too unproblematic. We care little for interest and rush into principle, preferring purity of principle (or “ideology”) to tolerant harmony, and rejecting both the egotistical calculation and the urbane civility required for furthering one’s interest. Into this fraught situation steps Stanford’s Morris Fiorina—able, cool, and genial, wearing the maestro’s mantle of V.O. Key, ready to save the relevance and reputation of political science to our politics. He points out in recent essays written for the Hoover Institution that polarization is far from complete: in fact, more people dwell between the parties than are to be found at either extreme. In political science-speak, the median voter is the modal voter, indeed in Fiorina’s view, the model voter. He characterizes recent party history as a period of “sorting,” in which the parties have sorted themselves, liberal Republicans sent home to the Democrats and conservative Democrats to the Republicans, together leaving behind mostly non-partisans in the middle. Fiorina rather likes these sensible folks, whom he calls “normal,” intending a compliment as opposed to the abnormal zealots in the partisan extremes.

In his view, democracy is, or ought to be, the rule of the ordinary, normal people who quite reasonably turn their backs on partisans and refuse their restless agitations against our peaceful, productive comity. Call them “apolitical” if you will, but they and not their supercilious critics are the salt of the earth. Their only defect is being unable to defend themselves against over-political moralism, yet happily they have Mo Fiorina who has volunteered to come to their aid at no cost to them. If he wanted to, he could point out that zealous divisiveness was the main reason why political parties were once thought by America’s founders (particularly George Washington in his Farewell Address) to be the bane, not the salvation, of a free society. It is therefore doubtful and disputable that either interest or principle counsels “collective action” in the form of political parties.

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The form; there’s the rub. Rational choice (so-called “formal theory”!), for all its preoccupation with collective action, pays no attention to the form it takes, assuming as it does that players in a made-up game called the “prisoner’s dilemma” (which maps cooperation between supposed rational individuals) are analogous to a party system. But Fiorina has the merit of introducing form in the everyday notion of “sorting,” which is how he describes the process of polarization. Each party has a form of policies and ideas by which its partisans can be sorted out from those of the other party, and this is what Democrats and Republicans have been doing with a vengeance in recent decades. For an image of sorting one could think of the typical husband’s job of emptying a dishwasher and sorting the plates by their shapes. Somehow human beings have the faculty of recognizing the shapes, kinds, or forms of things. But when applied to parties, sorting has two extra qualities: the fact that humans, unlike plates, are sorting themselves, and the fact that, unlike plates—which don’t care about other plates—parties are sorts opposed to each other.

It is amazing but true that the political science of parties makes nothing of the obvious fact that parties are opposed to one another. In all their thoughts and actions the parties address each other; what one likes the other dislikes, what one does the other wants to undo. They do battle every day in every way. They are not merely “on the one hand” or “the other,” two separate composites to be sorted by the political scientist. The usual designation of Left and Right is inapposite, because normally the two hands cooperate. Parties do not cooperate, and ally for a time only when they must. They form themselves by action that is reaction, the Jeffersonian Republicans against the Federalists, the Lincoln Republicans against the Democrats. Aldrich does say that a party “acts and reacts,” and other political scientists recognize party conflict, but they do not explain how and why the parties are formed by reaction and conflict both in their origin and in their daily practice. They neglect the animus of party spirit emphasized by three recent authors in political philosophy: Andrew Sabl in Ruling Passions (2001), Nancy Rosenblum in On the Side of the Angels (2008), and Russell Muirhead in The Promise of Party in a Polarized Age (2014). But political philosophers have a professional interest in the study of principles (and, which is less known, of the passions they inspire).

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James Campbell lives in the realm of statistical quantification, dropping words like “bimodal,” using concepts like “the McClosky Difference,” and displaying numerous tables and graphs that give shape to numbers. But his writing is forceful and clear, and his book is far from forbidding. He announces to his “quant” colleagues that the real story of polarization “has not been told before now.” He produces the evidence for polarization, both direct and circumstantial (on which more later), wherever one can count: in Congress, in elections, and in surveys of the population. Distinguishing the extent of polarization from change in polarization he concludes that the parties were already polarized in the 1970s but have recently become more and more so. In Congress there is now virtually no overlap between the parties in the measures of the (liberal) Americans for Democratic Action and the American Conservative Union, which take stock of members’ votes: “from 2005 to 2012, every Democrat was to the political left of every Republican.” As against the view that George W. Bush was the great divider, Campbell notes that in approval ratings Barack Obama was no less so.

To explain the change toward greater polarization Campbell provides a summary of party history, not from the inception of party like Aldrich but from the last half of the 20th century. It was the Democrats, he says, that began it with a move to the left in 1958. After the Democrats made their move, which quickly brought African Americans into their party, the Republicans replied with the slower absorption of Southern conservatives that ended in a greater move to the right. Campbell counts eight steps from the 1950s to the present—a messy trail that makes it difficult to conclude that voters act mainly on interest. He insists as well that this increase in polarization came from the bottom up, not from the top down. He agrees with Key that voters generally know what they are doing.

With this evidence of present attitudes and party history Campbell asserts, contra Fiorina, that polarization, not refusal to polarize, is “normal.” He rather prefers partisans to non-partisans, partisanship to apathetic inattention, and he notes that, although non-partisans add up to a plurality, the partisans added together are a majority. The parties are not only cohesive, and not only different, but also “antagonistic”—which means antagonistic to each other. Though Campbell does not explicitly make the contrast, they are not agencies of different interests, implying the possibility of compromise or even harmony; they are carriers of principle opposed to the principle of the other party. Parties define themselves, rather than being defined by external causes such as interests, and they define themselves against the other party or parties.

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Going beyond Campbell, one could say that parties are antagonistic in argument. What do politicians mainly do? In public and in many private moments, they argue. They debate with friends and opponents, offering their own opinions and in the process refuting those of their opponents. Even when thinking strategically or tactically, they look to promote their own opinions and look for weakness, whether in persuasiveness or logic, in those of their opponents. The practice known as “spin” is in the realm of argument (rhetoric being the counterpart of dialectic, as Aristotle said). One can win by use of force or by winning the election, but the necessity remains to win the argument by justifying one’s victory—particularly if, as in elections, the opponent remains on the field, thinking darkly of return.

Campbell reckons that because polarization of opinion is normal, the median voter is no longer the object of attention. Rather than being the stable decider parties must gain over, he is pushed around by the extremes, in recent years toward the right. The median is mobile, Campbell says. There are more votes to be had by turnout of the party base than by compromise to persuade the middle, and that is the strategy parties have pursued. Here is another suggestion to him: besides the ignorant, apathetic, and pseudo-independents who habitually lean to one side, there is in American opinion an element of the traditional anti-party feeling mentioned above. Aldrich’s view of party history alludes to the need to hold the principle that partisanship is legitimate, the precondition first set forth in America by Van Buren. Aldrich doesn’t make much of his observation, but party can be in one’s interest only if the principle is adopted that party is respectable, not contemptible. Party politics in our day are so divisive as to make many concerned citizens question Van Buren’s pluralism and wish to revert to the founders’ hostility to party government. Political scientists need to take more seriously the principles both for and against party, principles that direct one’s interest rather than having been dictated by one’s interest. A guiding principle is a “cause” of party behavior in a different sense from a cause that has effects; it does not precede but accompanies the behavior. As Campbell carefully says, parties “join” or “bind” their members; parties are not factories that manufacture members.

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Campbell makes a point of distinguishing direct evidence of partisanship from indirect or circumstantial evidence: direct evidence is one’s own, “self-reported,” as in a survey; circumstantial evidence is ascribed by an observer in an analysis. He finds direct evidence to be more compelling, as when Neustadt the voter called himself a Democrat. That, and not some external ascription, was his reason for voting. A reason is a general proposition applying beyond the particular instance. Perhaps it wasn’t in the interest of a Democrat to give himself a reason, since the reason could justify the opposite vote of a Republican. Thus a rational interest expands into a principle, leaving behind the arbitrary preference of an isolated individual. This is how a theory of interest goes beyond its apparent selfishness, in a manner often overlooked by the theorist and his admiring followers. Campbell, with his preference for the self-reporting evidence of those who declare their partisanship, suggests a return to the political science of yore that would begin from the claims contained in opinions and declarations like Neustadt’s.

By emphasizing the importance of principles and ideas over any imposed explanation from interests and imputed choice, Campbell has fashioned a better analysis of our parties’ polarization than any I’ve seen. He has a moderate love of quantification that doesn’t always serve him well, particularly in attempts to make numbers out of the differences between liberals and conservatives, but this may be strategic rhetoric designed to protect his professional reputation.

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There are two phrases in his excellent book that reveal the promise of his thinking. One is that there are “a great many routes” by which one acquires one’s political perspective. This means that one must start from the perspective, the opinion. A liberal or a conservative cannot be understood from one of the many routes by which one becomes a liberal or conservative, since another could easily have been chosen. Analysis through interest or rational choice is arbitrarily selective; it tries to jam the many routes into just one.

Campbell’s other promising phrase refers to congressional leaders who “appear to be leading or misleading their parties.” Aha! Leaders can mislead, in which case they are not leaders but misleaders. Political science wants to be neutral, but “leader” is no more neutral a term than “misleader.” The ascription of the term “leaders” to misleaders is misleading. Instead of leading their profession and the public to understand better, political scientists are misleading them by refusing to follow fact into value. Their refusal—when it calls misleaders “leaders”—results in giving value unjustly and describing fact incorrectly. With this inconspicuous phrase Campbell points forward to a political science that has abandoned the fact/value dichotomy. For one cannot simply take for granted the accuracy of self-reporting, of partisan political assertions—to this degree the self-emasculating political scientists who dismiss opinion are surely right. So political science needs to go beyond the description of polarized parties to see whether polarization is just or necessary, as the partisans claim it to be. James Campbell introduces American political scientists toward the path of greater accuracy and relevance.