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Denial of “deterrence by denial”
posted December 31 2014 by Ward

Recently there was a little colloquy on Facebook about “deterrence by denial.” A physicist friend of mine posted a query asking people if they could help him define “deterrence by denial.” Or just explain clearly what it was. There was a good deal of back and forth—maybe thirty posts—with various opinions and the original author chiming in with follow-up questions. I came across the discussion a day later and posted this:

Ward Wilson—Geoffrey: I think Jeffrey is right, although as a historian I have a slightly different explanation. Deterrence was not a big deal in antiquity. War was about what your opponent could do to you and what you could do to him (her). Some clever leaders used mind games, most concentrated on practicalities. That's why you end up with a lot of physical stuff like walls and moats. Great empires like the Assyrian Empire were not built on sudden advances in deterrence theory, they were built on new and better war technology (iron weapons in that case).

Sometime in the 1930s deterrence came into vogue. (Seriously into vogue. Like a highly contagious disease that sweeps through a population in weeks. Think of it as the intellectual equivalent of the flu epidemic of 1918.) Most people think this happened because of nuclear weapons; I don't. I'm hoping to write something about why deterrence rose when it did, so more about that later. But for whatever reason, deterrence became all the rage, it was the hottest new explanation, everything seemed to depend on it. (It was, after all, at the center of US defense policy.) Deterrence began to crowd everything else out of the intellectual space. So non-nuclear folks started scratching their heads and wondering if maybe this newfangled idea was for them, too.

And before long they figured out a way to make deterrence relevant to what they did--building walls, working on defensive measures, making new kinds of rifles, whatever. They called it deterrence by denial.

The problem with deterrence by denial is reflected in this conversation. Is it based on what you say? Or what you do? Is it a threat? An action? Both? If it's based broadly on everything you do or say, then what is ruled out? What is _not_ part of your deterrence by denial? (Something that is everything is, by definition, nothing.)

It is true, as some deterrence theorists argue, that there are many factors that go into the decisions your adversary makes in wartime or leading up to war. And it might be possible to influence that calculation.

The problem is twofold: first, not all "decisions" in war are fully rational (or even partly rational.) Deterrence by denial matters not a whit if your opponent is crazy or even just crazed with rage. It also tends not to work if your opponent is self-deluding. Sadly, most of us are self-deluding surprisingly often. (New Year's resolutions are an especially timely reminder of how vulnerable we all are to self-delusion.) Affecting the mind of your opponent is often far less important than affecting his/her emotions/urges/instincts. Deterrence operates far less often than its (many) proponents claim.

Second, if everything impacts the rational calculation of costs and benefits your adversary makes, how can you sort out the contribution of deterrence by denial? It may be that it works, but it's effects are entirely unmeasurable. What prevented the attack? Was it the trenches you ordered your troops to dig? Or the impending torrential rain storm? Or you opponent's astrologer's advice against attacking on a Tuesday?

Deterrence by denial suffers from the same disadvantage that nuclear deterrence threats suffer from: it's entirely psychological. The problem with psychological stuff is that it's pretty hard to get a ruler inside someone's head to measure with. Science is measuring, testing, and the ability to reproduce results. Can't do that with deterrence. Hell, we're still arguing over whether Freud's ideas about dreams are true or not. Seventy-five years later we haven't been able to prove or disprove fundamental ideas about psychology. How can we expect to track down the psychological factors in a high stress decision based on the testimony of people (leaders) who have an interest in obscuring their real thinking from us (assuming they even know)?

Deterrence by denial is a badly defined, unclear, not very useful concept. It argues that you can affect your adversary's thinking and sometimes dissuade him from doing stuff. Clearly true. But provable or measurable in any meaningful way? I don't think so.

I think there's a good reason why you don't understand deterrence by denial. I don't think it's a very sound notion.