FBI Director James Comey gave a speech at Kenyon University’s Center for the Study of American Democracy last night. His speech focused on encryption, the divide on privacy priorities, and the issues relating to the recent court case involving Apple and the San Bernardino iPhone 5C running iOS 9.

The speech is embedded below. Director Comey doesn’t actually walk on stage until a bit more than 20 minutes in (at about the 20:50 mark).

Comey’s speech seemed heartfelt, with a focus on having a reasonable discussion about privacy and encryption. He stressed the need for both sides to be listen to the other and be willing to be wrong. Personally, I like the man and I sense that he recognizes the legitimacy of both sides of the argument, that he finds himself in a difficult position.

Comey does an excellent job laying out all sides, though he still seems to be missing a basic premise of this discussion. He focused on the fallacy of slippery slope arguments, arguing that Apple’s case depends on the concept of inevitability, that it is inevitable that if Apple helps the FBI, the source code/skeleton key/backdoor will fall into the hands of the wrong actors.

This is a subtle but critical point. And I think it is where Comey misses the mark.

If you leave a big pile of cash on a chair in the middle of Times Square, with guards on either side of it, is it inevitable that that cash will disappear? No, certainly not. Is it inevitable that someone will at least consider trying to steal that cash? No, but certainly that is much closer to inevitable.

All that said, would you be willing to leave a pile of cash on a public but guarded chair? No. Not because the cash will inevitably disappear, but because there is a real threat that someone will try to steal that cash and because there is a non-zero chance that they will succeed.

Obviously, there is a universe of differences between the cash chair analogy and the Apple FBI case. There is no benefit to leaving your cash in public. The cost of making it possible for the FBI to break into an iPhone is in privacy and security. The benefit is in helping fight terrorism. This is not a one sided argument.

But Comey’s speech homed in on inevitability as the heart of Apple’s argument, that Apple was saying that it is inevitable that if they help the FBI, the bad guys will gain the ability to break into iPhones.

But inevitability is the wrong word on which to focus. Instead, ask yourself this: Is there a likelihood that bad guys will try to get hold of the mechanism used to break into the iPhone once it is created? Of course. And is there a guarantee that Apple and the FBI can both 100% prevent those bad guys from getting that mechanism? No, of course not.

And that’s the difference, that’s the core of the argument. The possibility of failure, however slight, is the issue.

I want to complement Director Comey on his openness and his call for all parties to listen and respect both sides in this important discussion. Well done.

One final note: At the end of FBI Director Comey’s speech, he entertained questions from the audience (at the 52:04 mark). In response to the first question, Comey talks about the possibility of revealing (to Apple) the technique used to break into the San Bernardino iPhone (they haven’t decided) and makes the point that the technique they used has a very narrow focus, will only break into the iPhone 5c and earlier (not the iPhone 5s or iPhone 6, for example).