Anti-liberalism is having a moment. And it's happening at all points of the political spectrum.

Suicidal religious fanatics now strike regularly at the very foundations of free and open societies in Europe. Those attacks help to inspire anti-liberal forms of nationalistic populism in countries on both sides of the Atlantic (think Marine Le Pen in France, or Donald Trump in the U.S.). In response to the electoral power of the right and selective willingness of moderate politicians to compromise with it, an anti-liberal left (think the socialist Jacobin magazine) has risen from the dead to challenge the liberal order, using concepts and categories derived from the Marxist tradition of social theory.

True liberals have plenty to say in response to the critics that increasingly encircle them. Some lines of defense focus on the importance of upholding such liberal norms as equal respect for individual rights and tolerance of disagreement. Others point to the concrete goods that liberals have and will continue to accomplish in the face of intransigent opposition. Still others highlight the possible unintended negative consequences of empowering the state to level hierarchies and stamp out injustices.

Then there's the effort to highlight the pernicious political consequences that can follow from illiberal intellectual habits. I'm thinking above all of totalitarian forms of political argument — and specifically the tendency of those influenced (sometimes unknowingly) by Marxism to embrace the goal of "heightening the contradictions."

The idea is simple, powerful — and insidious. Radical critics often seek to spark dramatic change, but they can't see a direct path from the status quo to the vastly improved world they hope to bring about. This gives rise to the idea of searching for a catalyst within the present that can serve as a launching pad for total revolution.

Seeds of the idea can be found in the writings of G.W.F. Hegel, the early 19th-century German philosopher who described historical progress as a dialectical process in which social, cultural, intellectual, and economic contradictions emerge and resolve themselves, only to produce new contradictions, crises, and resolutions, and so on down through the centuries and millennia. Hegel thought that this process ultimately culminated in the modern liberal nation state, which contains resources necessary to resolve the contradictions that continually rise within it.

Karl Marx disagreed — and his dissent had enormous consequences on world history. Instead of suggesting, with Hegel, that the historical process had culminated in liberalism, Marx insisted that the contradictions that arise within the liberal political economy will prove just as fatal to the capitalist order as contradictions within the medieval world were for feudalism.

These contradictions of capitalism — between capital and labor, for example, or more specifically between the restricted consumption of the masses (due to low wages) and the limitless expansion of capitalist production — would eventually reach a crisis point. From the resulting conflagration, a new order would emerge in which all contradictions would be resolved. The goal of the revolutionary political actor must be to hasten the cataclysm that destroys the old order and brings a future one into being.

How can that be accomplished? That's where "heightening the contradictions" comes in. In abstract terms, it means working to intensify the things about capitalist society that will ultimately produce its overthrow. In concrete terms, it means allowing and even encouraging things to get worse in the hopes that people will be inspired by their misery to undertake radical action.

The crucial importance of heightening the contradictions explains the otherwise inexplicable hostility Marx and Friedrich Engels display in the closing passages of The Communist Manifesto toward non-communist socialists for embracing "reform" instead of revolution. The same impulse can be seen in all of Marx's most influential successors, from Vladimir Lenin and Rosa Luxemburg on down to the pantheon of Third World revolutionaries who inspired political insurrection across the globe throughout the mid-20th century. All of them rejected individual ("bourgeois") rights as well as the legitimacy of the liberal welfare state, no matter how generous, on the ground that it functions as a bribe that buys off the working class with half-measures, leaving the contradictions of the present order intact, with no way out, and no end in sight.

Much better, in the short term at least, is the immiseration of the working class so that it will rise up and take the radical actions needed to overthrow the system as a whole.

Since the collapse of the Soviet Union, there haven't been a lot of doctrinaire communist revolutionaries running around. But that doesn't mean that the idea of heightening the contradictions has disappeared. On the contrary, it has spread like a virus to other forms of anti-liberal political extremism.

Radical Islam, for example, is a highly potent mixture of motifs drawn from the Muslim past and Marxist-Leninist ideas imported through the writings of such polemicists as Sayyid Qutb and Abul Ala Maududi. The two most ambitious and powerful Islamist groups — the Islamic State and al Qaeda — do not seriously believe that their acts of terrorism against the West will lead the EU or the United States to surrender.

Their strategy is more patient and indirect (a Marxist would call it dialectical). They want their attacks to provoke a far-right anti-Muslim backlash within Western countries that will in turn inspire persecuted Muslims within those countries to become radicalized and willing to undertake ever-more spectacular attacks against their host societies. Attack, crackdown, worse attack, more draconian crackdown, on and on, with the West eventually weakening enough that a resurgent Islam can rise as a triumphant global power.

Make things worse to make things better: a classic case of heightening the contradictions.

Interestingly, the strategy has also been deployed by the more radical factions of the Republican Party. The idea may have entered the GOP bloodstream through the influence of the original neoconservatives (who cut their ideological teeth on Leon Trotsky's anti-Stalinist Marxism). Or it might have come from the writings of radical community organizer Saul Alinsky, which influenced both Newt Gingrich and the rise of the Tea Party. Whatever the case, the party's efforts to cut government spending — sometimes called "starving the beast" — take a dialectical form that any good Marxist would recognize. First deprive government of the revenue and resources it needs to function properly. Then point to the resulting poor performance as evidence that government spending deserves to be cut further. Which leads to worse outcomes. Which provokes louder calls for still deeper cuts and perhaps even sparks a major grassroots push to overturn the welfare state once and for all.

Marx the Champion of the Working Class likely would have been appalled by the ways that Islamists and libertarian Republicans (both of whom he wouldn't have hesitated to dub reactionaries) have appropriated and deployed his dialectical ideas. But he would have no grounds for surprise.

Counseling political actors to heighten the contradictions is simply Machiavellianism raised up into a providential principle: History is on your side, so you are permitted to do absolutely anything to win, including acts (like deliberately making things worse) that would normally be judged unambiguously evil.

Everything is permitted, because history says so: That is Marx's lesson.

And it's one that no liberal can ever accept.