There is a strong parallel between foxes and hedgehogs in methodology on the one hand, and pluralism and monism in politics on the other. Pluralism is a body of philosophies that argue that people should have the freedom to live by very different ideals; its spirit is best captured by the phrase “to each their own.” Monism, on the other hand, is the belief that there is one form of righteousness, one truth, one moral compass. The idea that “legislating morality” is bad is alien to the monist; what else is legislation but laying out what is considered right and punishing those who do wrong? You can think of a fully integrated religious, political, and social order as embodying monism; Europe when it could properly be called “Christendom” would be one example from history. On the other hand, a country that has no official church and in which Christians, atheists, Jews, and Muslims are all considered legitimate groups among the citizenry is a pluralist order.

To spell out the parallel: monists believe in one unified moral order just as hedgehogs believe in one idea that can explain everything, and pluralists believe in many ways of life just as foxes believe in many distinct models. In many ways, we can speak of methodological monists and pluralists just as meaningfully as political ones.

To defend methodological pluralism is to make certain claims about the limits and the capabilities of human knowledge. On the one hand, we concede that–at least in some areas–we are unlikely to find a one, true model to rule them all. On the other, most method pluralists would say that we can find some truths, and even make accurate predictions, in specific contexts. There would be no point to the pursuit otherwise–a point of agreement between monists and pluralists.

Moreover, it is clear that the advancement of science can be served by having a lot of method monists with a wide variety of models that they apply and pursue the implications of relentlessly within their subgroups. Economics is arguably richer because of its initial separation from psychology followed by a period of intense cross‐​discipline dialogue.

But evaluating these claims about method pluralism requires broad agreement on certain values we’re seeking to promote–more accurate explanations, perhaps, and more reliable predictions. These shared values are a monism that serve as the basis for pluralism itself.

Seen in this way, pluralism is not truly a disunity of perspectives; it is merely a very thin unity. Arguably, pluralism is a strategy for economizing on unity, rather than replacing it entirely, which would be impossible. In methodology, this might work best in areas where less is known and the subject is highly complex. Numerous small, tactically applied models might be able to more easily capture specific insights in specific contexts than a single grand theory of everything. In politics, monistic orders existed for dramatically smaller populations. It could be that monistic politics exhibits diseconomies of scale; the cost of unity scales exponentially rather than linearly, meaning it is harder to obtain for bigger populations than smaller ones. The work of James Buchanan and Gordon Tullock certainly suggests as much.

In politics this thin unity is accomplished with a broad‐​based buy‐​in for a set of procedures and institutions which promise a degree of orderliness and a fair chance at advancing any given group’s agenda. “Fair” does not mean “likely to occur,” so much as having the freedom and opportunity to engage in persuasion.

That is another big unity necessary for pluralism–agreement that persuasion is a morally superior means of pursuing reform and group action in general than conquest and intimidation. A faith in the virtue of rhetoric over coercion may be the most important part of a pluralist order.

This consensus, however historically unusual, is still very thin–the range of incommensurate narratives that persist within this framework can and have been very broad indeed. The truly partisan pluralist is the person who believes this broadness is good in itself, apart from whatever historical particularities made the economizing of consensus a practical necessity.

The partisans on its behalf must rely on monistic rationales for its justification. Examples of such justifications in politics include Friedrich Hayek’s argument that the freedom a pluralistic order entails allows for a vast discovery process that brings about material and intellectual progress. In methodology, we can draw on complexity theory and similar fields to argue that nonlinear systems are often predictable within localized contexts, but highly unpredictable on the whole.

Notice how both justifications argue on behalf of a plurality of approaches, while still making straightforward assertions about the system as a whole and why it is good. The bottom line is that pluralism of any sort can never go all the way down. It must rest on a foundation of basic consensus, which sets limitations on variation and grounds the whole endeavor. For this reason, liberal neutrality is not truly neutral, but conceding that does not require us to abandon pluralism as a project. It should simply inform how we formulate our defense.