A deterministic algorithm can still be unpredictable in a sense. In the extreme case, a procedural generator (like in Minecraft) is deterministic given a seed, but you will still have trouble predicting what you get if you change the seed, because internally it uses a (pseudo-)random number generator.

So there’s still the question of how controllable the LLM really is. If you change a prompt slightly, how unpredictable is the change? That can’t be tested with one prompt.

> I think you mean non-deterministic, instead of probabilistic.

My thoughts too. It's more accurate to label LLMs as non-deterministic instead of "probablistic".