Shmi comments on Epsilon is not a probability, it’s a cop-out

[Shmi]

I tend to use ε for shorthand for cases where there aren’t any sensible ways to update to, say, 5% probability of the thing happening.

Well, why don’t you use zero instead, what is the difference, instrumentally?

[SarahSrinivasan]

Because remembering the structure of things is instrumentally useful.

[Richard_Kennaway]

Saying zero would draw out pedants saying, “but zero isn’t a probability, are you really infinitely certain, etc. etc.” Although personally I would just say zero and ignore the pedants.

[Dagon]

Ignoring pedants is correct, but I find value in the acknowledgement and reminder that it’s not ACTUALLY zero, but just small enough for me not to estimate it or think much about it in normal circumstances.