I’m a hydrologist.

A big part of my job is doing math about floodplains, which means I get to see firsthand how poorly the public understands the most basic laws of statistics.

First, let’s pretend your home is in a floodplain as defined by FEMA, meaning there is a 1% annual chance that it will flood.

Next, let’s pretend that FEMA, and the engineers doing the flood modeling, got all the math right (this is actually a pretty big leap, but that’s a discussion better suited for a different article).

“1% annual chance” doesn’t sound like a lot. It sounds like an easy thing to gamble on. But people forget that a 1% annual chance gets “re-rolled” once a year, and the chance of it flooding once, over a wider time-span than just one year, adds up, and it adds up in a very specific way based on the laws of probability.

This is actually a simple example of a “Bernoulli Process,” but let’s skip the mumbo-jumbo. Here’s how any mathematical muggle could do the calculation on the back of a napkin.

A 1% chance of flooding is the same as a 99% chance of not flooding. The chance of not flooding over two years is (0.99) * (0.99), or more mathematically correct, (0.99)^2. The power is the number of times you roll the dice, or the number of years your house sits in the floodplain.

So the chance of not flooding over 30 years (the length of a typical mortgage) is (0.99)^30, or 0.74. That means there’s a 26% chance of at least one flood over the life of that mortgage. Dice suddenly don’t look near as great, do they?

This is why flood insurance costs so much, or rather why it should probably cost more than it currently does.

But this article isn’t about floods. It’s about worse things.

We estimate the probability of an event by piling up data and checking the number of times out of the total data set that the event happened.

If we start in 1775, the land we call the United States of America has had two major violent revolutions against its own government in the span of 242 years, for an annual chance of 0.8% per year. The first one, the American Revolution, was successful. The second one, the Civil War, was not, but for the purposes of this analysis they are both qualifying events.

Now that might be cheating a little bit, since I’m setting the time-span the year before the first one happened, but we could go back to the founding of the colonies at let’s say approximately 1650, and cook up a probability of 0.5% per year for major violent nationwide revolution.

We could also do such an analysis for other countries (defined here as “bits of land”) around the world, and probably get numbers far in excess of 0.5% per year. If we cast a wider net, and included the war, internment, and genocide of native Americans in our mathematics, then the numbers here go way up.

If we simply include traditional war in the numbers for other countries, their numbers go fantastically up. So I would say the probabilities above are likely on the low side.

At an annual chance of 0.8% per year, the USA has a 55% chance of a major violent revolution in any given 100 year span. At an annual chance of 0.5% per year, we have a 39% chance of a major violent revolution in a given 100 year span. On our soil. That’s just math.

These things are much worse than floods, and the people who suffer during them are largely not the elites running the show, they’re the people at the ground level, whether they’re participating in the revolution or not.

Syria is sitting at almost half a million dead and around ten million displaced into Europe and that revolution is still only about half-cooked.

Those people mostly aren’t combatants, those are women, children, families, who got stuck in the middle of something they couldn’t see coming, and for which they were woefully ill-prepared.

Nobody sees these things coming. If they did, they wouldn’t happen. And when they happen to modern countries, which are tremendously dependent on civil infrastructure and supply chains to get the necessities of life such as water and food, the humanitarian impact for the poor and defenseless is staggering.

When people on the modern left question my commitment to keeping firearms in my home, I often ask them whether they think the USA will last “forever and until the end of time,” they don’t know how to answer this question, largely because my left-leaning friends put emotional faith in institutions of authority.

They usually answer, “Well, no, but it’ll certainly last my lifetime.” So I ask them about their kids’ lifetimes, and their grandkids. What would they do if it happened?

Mathematically, something like this is certain to happen over a long enough time-span, and we can use mathematics to project the likelihood of it happening over any given time span, by synthesizing data. All the data I see seems to indicate that having a plan for it is probably much more valuable than having a plan for tornadoes, or floods.

Setting constitutional scholarship aside, which is typically built on retrospective thinking geared towards justifying prior-held opinions, I view gun ownership as a direct hedge against the suffering of the poor and helpless during these violent situations. I don’t think owning guns is a complete solution to protecting your family in a violent revolution or anarchic situation, but I do think it’s an essential piece of the overall puzzle.

You need a safe place to go, a way to protect yourself on your way there, and a way to defend that safe place if necessary from desperate people who didn’t have a plan. And you cannot rely on an authority to provide you that protection when the authority itself is in question.

That, too, is just math.

And with Communists and Nazis openly clashing in our streets, I believe it is math worth thinking about.

** Courtney Camp is a U.S. citizen who can do basic mathematics. This is Camp’s fourth article for *Being Libertarian*.*

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