If you are a true conservative – and I use the term not as Ted Cruz might, but in its literal sense, as in conserving what is of value in the modern world – then you should be obsessed with three threats to the most vital parts of our civilizational heritage, all of which are coming to the fore: war, pandemic and environmental catastrophe.

These three events have frequently caused or contributed to the collapse or decline of great civilizations of the past. After being seriously weakened by pandemics and environmental problems, the Roman Empire was taken over by barbarian tribes. The Aztecs were conquered by the Spanish, who had superior weapons and also brought disease. The decline of the Mayans likely was rooted in water and deforestation problems.

I think of true conservatism as most of all the desire to learn from history. So let us take those lessons to heart.

The odds are that nuclear weapons will not be used in the war in Ukraine. Still, there is some chance of a major escalation, or the deployment of other weapons of mass destruction. That chance is difficult to estimate, but it’s not crazy to put it at or above 1%. A desperate Vladimir Putin might well resort to a strategy of escalation, if only as a misguided attempt to de-escalate.

Here is the dilemma: If you play that “1% chance of massive destruction” repeatedly over decades, sooner or later an actual escalation is going to erupt. The cumulative probabilities of a major nuclear exchange are not actually low, even if the probability is low in any single war.

A true conservatism thus ought to make limiting the probability of a nuclear exchange its top priority. Such an emphasis would not itself solve the problem, of course. Nonetheless, any observer of American political debate for the last 20 years or more will admit that the issue is nowhere close to a major emphasis.

This brand of conservatism does not necessarily insist on higher levels of defense spending, as conservatives pushed for in the 1980s. But it does suggest that alliances, military readiness and flexibility are major policy issues. If more defense spending is called for, that should be the federal government’s No. 1 priority. While President Joe Biden so far has done a reasonable job executing America’s Ukraine policy, he has not made these issues top priorities, nor have the Republican or Democratic parties. When was the last time a major politician gave a speech about how long the military procurement cycle has become, relative to the pace of technological change?

The relevance of pandemics is all too obvious. Still, Congress is dragging its heels on a $10 billion pandemic assistance bill, and snags remain. The final legislation is unlikely to include a global component, despite the continuing risk of new virus strains from abroad. The U.S. should also be looking to gear up for an Operation Warp Speed No. 2, directed at developing a pan-coronavirus vaccine, effective against a broad swath of possible future strains.

Even after more than 1 million excess deaths during this pandemic, Americans are still not taking pandemic risk seriously. Is America so much better prepared for the next time around? If you ask the simple question of whether the government has reformed or improved the CDC, FDA or NIH – regardless of what kind of reforms you might favor – the answer seems to be no. America continues to just putter along.

Finally, a true conservatism would prioritize the most important environmental problems. To use a specific example: It should not take seven years to get permits for an offshore wind farm. Just accept the reality that wind farms will involve some modest environmental problems of their own and get on with building them.

Unfortunately, even as environmental regulations proliferate in the U.S., there is an unwillingness to push through a carbon tax or make nuclear power plants easier to build. America is getting the big stuff wrong, in part because it is focused on politics over policy. Consider that California’s governor has proposed giving car owners a $400 gas-tax refund, while the Biden administration is more worried about jobs and competition from China than about trying to make solar panels as affordable as possible.

The main task of a revitalized conservatism should be to restore America’s moral seriousness on these issues. At the moment, neither political party is doing that.

Tyler Cowen is a Bloomberg Opinion columnist. He is a professor of economics at George Mason University and writes for the blog Marginal Revolution. His books include “Big Business: A Love Letter to an American Anti-Hero.”