In short, what we have is a long-standing, significant controversy, especially evident in the intense heat of this election cycle. What we don’t have is very much clarity on what these terms really mean, not just by definition, but in actual practice. Does pluralism in religion mean that we should welcome the prayers of Satanists to open our local government meetings, as happened recently in Alaska? Does a commitment to cultural diversity mean a completely open immigration policy, even if some immigrants may be terrorists? A little light amidst the great heat might help us sort things out.

First of all, let’s think about the terms “diversity” and “pluralism,” laying aside “multiculturalism” for a bit while we gain some needed clarity. Most people think of “diversity” and “pluralism” as rough synonyms, meaning something like “a whole lot of different kinds of things.” But that doesn’t tell us much, least of all whether they are good or bad, so we should try to get a more exact understanding of these terms.

“Diversity” has some root in the understanding that, in any complex whole, a number of different parts are needed for it to run well. So, to take an obvious example, there are a diversity of human organs, which together make a functioning, healthy human body: liver, heart, lungs, pancreas, feet, toes, hands, fingers, eyes, ears, mouth, tongue and so on. The diversity of parts isn’t randomly contrived, but (we might say) organic, each having its place in a needed, proper functioning of the body. Homogeneity would be harmful. A human being made up of ears is not a human being, but a monstrosity.

The same could be said, at another level, in an ecosystem. In the several acres surrounding our house, there is an open meadow, with a number of different grasses and wildflowers, which the bees, grasshoppers, leafhoppers, katydids and other insects, field mice, shrews, rabbits and deer enjoy. And there are also raccoons, hawks and coyote, which enjoy the field mice, shrews and rabbits. We also have killdeer, sparrows, swallows, goldfinches and purple finches, which enjoy the grass and flower seeds, as well as the insects.

The ecosystem is diverse — a kind of harmonious but dynamic equilibrium — where the diversity serves a kind of hierarchy of life. Again, homogeneity — such as in killing off all but one kind of grass, one kind of insect and one style of bird — would be harmful to the actual health of the ecosystem.

One can also take diversity to another level, that of human economic society.

Human beings are born — as the ancients said — “naked with reason and hands,” that is, with a whole lot of needs which have to be fulfilled by human economic activity. We need mothers and fathers, who bring us families, and work to support them, so we can have a society. We need people who grow food, and we need people who sell food; we need people who make shoes, pants, dresses, shirts and coats, and we need those who sell them, as well. We need people who teach and people who look after the buildings in which we teach.

We need builders who build buildings and those who gather and prepare the materials for builders. We must adjudicate disputes about the law, and so we have lawyers. And since we are human beings who have deep intellectual and spiritual needs, the diversity of our economic society includes writers, poets, movie producers, artists, priests, nuns, brothers and musicians.

Here, the economic diversity serves the larger social whole defined by the complexity of the human good realized in society. As in the other instances of healthy diversity, economic homogeneity would be harmful. Imagine a society made up economically of nothing but mimes (cold shudder).

In all of these examples, diversity (properly understood) is a necessary and positive good. The whole needs the parts; the parts all work for the benefit of the whole.

Plurality is different. Plurality is — as the name suggests, especially given the way that many want to use it today — merely adding something for the sake of adding something, with no real understanding of whether adding that thing is harmful or beneficial.

So adding another leg to an already sufficiently endowed biped, under the assumption that more is better, is unhealthy. So would be a third foot or lung, or an extra nose. What we create is not a more harmonious human being, but a monstrosity. Merely adding one more, as pluralism dictates, destroys the harmony that defines the natural diversity of parts making up human beings.

The same thing is true of an ecosystem, which is a delicately balanced natural harmony. Like bunnies? Think adding rabbits for the sake of pluralism to an ecosystem is good? That’s what someone thought when he added a few to Australia. Since there were no natural predators, rabbits bred exactly like rabbits and mowed down every green thing in sight like a plague of super-cute locusts. Still think adding anything is good for an ecosystem? Try adding a giant pig farm, a shopping mall or a coal plant. Again, mere plurality — adding one more thing to an ecosystem — doesn’t tell you whether that addition will be helpful or harmful.

Economics? Let me see. Well, pornography is one more thing that can be added economically, and it makes a lot of money. But when you add it to society, you destroy marriages, pollute sexual innocence, degrade human beings nearly beyond repair and contribute directly to rape and sexual trafficking. Adding pornography to our economic system, in the name of pluralism, is hideously destructive.

Now we can come back to the yet-to-be-treated term “multiculturalism.” The problem with this term is that those who use it are never very clear about what they actually mean by invoking it. Are they adding something in the name of the diversity that actually serves the healthy social-political whole, or are they adding something in the name of mere plurality that could destroy it?

That’s an open question, one that shouldn’t be closed by those who shout down the other side. By “open” I mean that, whether it is a helpful or harmful addition can and should be something of the most serious political debate and shouldn’t be shut down by the jeering of the politically correct or the politically incorrect.

We need, therefore, to distinguish between diversity and plurality and be very clear about whether “multiculturalism” means adding what is helpful or harmful.

We in the Church need to be much clearer about all of this, as well. The Catholic Church firmly embraces real diversity and is rightly skeptical of those pressing for mere pluralism (usually under the banner of “multiculturalism”).

Thus the Church stands firm on the ground of basic biology and moral doctrine and affirms that human nature needs the diversity of two genders, but that adding any number above that for the sake of plurality leads to sexual monstrosity. A sign of the truth of the Church’s position is that those who have come out for a plurality of genders at any cost have created a monstrous 70-plus gender categories, with no end in sight, declaring that gender is not a matter of biology, but the morning’s wishful thinking.

The Catholic Church also embraces real economic diversity, that is, real subsidiarity, where there are layers of economic order built upwards from the family and local economy, and these layers are protected by law. But there are those passionately driving for the huge and monstrous homogeneity of a few super-sized corporations, which devour everything underneath them, including their own workers. The Church rightly opposes such homogeneity for the sake of economic diversity. But it also opposes plurality that harms the true good, as in (to repeat) the addition of pornography economically.

The Catholic Church is for real diversity in the culture, diversity that serves the true, healthy whole. 

But Catholic principles should also cause us to question an administration that allows a flood of Muslim refugees in from countries, while seeming to ignore the plight of Christians being slaughtered in those same countries from which they are fleeing, by allowing only a trickle of Christian refugees in.

There is also the real question about what effect it will have to suddenly shift from a Christian-based culture in a particular area to a Muslim-based culture through massive immigration. As post-Christian Europe is now finding out, there is a deep difference between a secular culture, a Christian culture and a Muslim culture.

We could go on with examples, but these at least may allow a bit of light in to our election-year debates.

Benjamin Wiker is an associate professor of political science at Franciscan University

and a senior fellow of Franciscan’s Veritas Center for Ethics in Public Life.