In this work, Christopher Cochrane addresses a topic as commonly referenced and yet as difficult to define as “time” is in St. Augustine’s Confessions (Book XI, Chap. 14): “What, then, is time? If no one asks of me, I know; if I wish to explain to him who asks, I know not.” Cochrane starts his investigation in a similar way: “When it comes to ‘left’ and ‘right,’ people seem to know it when they see it, but lose sight of it when they try to define it. Why might this be?” (p. 14).

Because of the difficulties in precisely defining the terms of “left” and “right,” skeptics doubt the usefulness of this commonly used dichotomy. As Cochrane himself acknowledges, “For some, these words are too simple to represent the complex reality of political disagreement. For others, their meaning is too vague. For still others, these words mean altogether different things in different countries or time periods” (p. 11). However, the proof that they are not “empty linguistic vessels” is to be found in their very persistence in the everyday language used to define and orient people in a maze of political disagreements, “despite the inability of thoughtful experts to agree about what these words mean.” Therefore, “left/right is still worth studying . . . because, like a stereographic picture, it seems to appear to us when we look at it closely, and then fades from view when we look at it too closely” (p. 6; emphasis in the original).

This refreshingly original understanding of the left/right problem informs the entire book. In an effort to remain true to his own “stereographic picture approach,” Cochrane tries—and largely succeeds—to stay close, yet not too close to the conceptual challenge raised by the left–right dichotomy. (The fact that the author chooses not to capitalize these terms, as many scholars do, is in itself telling). In order to achieve this goal, Cochrane both deploys and discusses a wide variety of approaches, ranging from philosophy to psychology, and from evolutionary biology to artificial intelligence, moving with ease from Wittgenstein to Ronald Dworkin, and from Karl Popper to F. A. Hayek. But the multi-perspective approach does not stop here; the combination of qualitative and quantitative methodologies is reflected in the book’s structure.

Chapters 2 and 3 are largely qualitative, challenging the classical way of trying to identify a “core” idea or dimension that underpins the left/right division. According to Cochrane, this is an attempt doomed to fail from the start, for “left and right, like ideology in general, emerge from the interconnections between ideas, but are not reducible to these ideas” (p. 32; emphasis in the text). Looking at the connections between actors and ideas in isolation, instead as of components of broader networks, will soon make these concepts “fade from view,” in the same way in which by looking too closely at the trees, one could fail to see the forest. The key word here is “seeing”—and the author is clear on this point: “The argument of the book . . . is not about how people think; it is about how people see. We often use words whose meaning we are incapable of articulating precisely. . . . We are ‘hardwired’ by evolution to perceive patterns, not to explain them” (pp. 32–33; emphasis in the original; see also p. 53).

After clarifying what we ought to be looking for—namely, patterns that emerge from similarities across multiple crisscrossing characteristics, like “family resemblance” (p. 28)—Chapter 4 undertakes the task of demonstrating where and how to look for these patterns on the left and on the right. In order to visualize complex networks, the author uses data from the Comparative Manifesto Project (CMP), a human-coded content analysis, quantifying the levels of agreement and disagreement between the manifestos of 301 political parties, across 54 policy categories, in 22 Western countries, since the end of World War II (65 years). Cochrane argues persuasively that it is precisely “the fact that a left/right pattern is so unlikely to emerge in the complex network of connections between all of these parties, issues, countries and time periods” (p. 63) that makes the discovery of such pattern in empirical analysis even more relevant, confirming the hypotheses previously advanced.

After reviewing the successes and limitations of existing measures of left/right positions and polarization, Chapter 5 goes on to “convert a rigorous conceptual understanding into accurate empirical estimates,” by proposing a model that converts “inputs” from CMP into “outputs” that estimate the left/right positions in national party systems, and comparing these estimates with the judgments of experts and citizens (p. 77). Combining measurements of the resemblance (“family resemblance”), relational (distance from the “center”), and diachronical aspects (persistence across time) of left/right positions, the model aligns surprisingly well with the empirical surveys. As such, the chapter “provides a bridge that links that understanding of left/right from previous chapters with the historical and comparative analyses that the subsequent chapters undertake” (p. 78).

Chapter 6 takes a look at the four schools of thought that have analyzed the contemporary relevance of past left/right divides—“persistence,” “irrelevant,” “transformational,” and “pluralization” theories—and concludes by finding all lacking: “Since the Second World War, and in advanced industrial countries, the cores of the left and right have expanded rather than changed” (p.124). In light of all these findings, Chapter 7 tries to solve the apparent empirical paradox that most voters, and few parties, are in the “centre” of the left/right divide, even in the American two-party system. Cochrane’s explanation is “that treating ‘the centre’ as a position in the same sense as ‘left’ or ‘right’ is problematic, both conceptually and empirically” (p. 144). The “centre” is, rather, the “vacuum” of left/right space, a relatively dispassionate “meeting place” between “those torn for different reasons between the left and the right” (p. 179). Finally, Chapter 8 focuses specifically on the peculiar Canadian case—which might also explain the author’s interest in this topic. For most of the twentieth century, Canada has been a “perplexing case” for failing to conform to the left/right divide. And yet, as Cochrane argues, in recent decades the Canadian political landscape started to increasingly resemble those from other industrialized countries, thanks largely to the “small world” phenomenon, which makes actors and ideas become similar by virtue of their membership in broader international networks.

There is much to recommend in this book, both substantively and methodologically, even though at times its strengths can become its weaknesses. Likely in an effort to reinforce the book’s main arguments, Cochrane repeats certain expressions and formulas (e.g., patterns of “overlapping and crisscrossing”) to the point where such repetitions become redundant. His quest for clarity ends sometimes in platitudes, such as: “Agreement brings actors together and disagreement pushes them apart” (p. 24); “[A]ctors are similar to the extent that they agree and dissimilar to the extent that they disagree” (p. 52). The reader might also get frustrated after hopelessly searching for an explanation as to why the Canadian rapprochement to the left/right divide begun in the 1980s and no sooner or later.

All of these shortcomings aside, Left and Right remains a useful and necessary read for political scientists—theorists and comparativists alike—interested in a fresh perspective on this recurrent topic.