[TeMPOraL]

Symbolic behavior is artificial and not how humans think either. 0 is not a probability (neither is 1) - a value of 0 or 1 basically breaks calculations by dragging everything along to the limit, the same way infinity does, or 0 in the denominator (in fact, that's what 1 and 0 translate to if you switch to logprobs or other equivalent ways to calculate probabilities).

Consider: if you clamp the probability distribution of answers to 2x3, so that it's 0 everywhere else and 1 at 6, you're basically saying that it is fundamentally impossible for you to misunderstand the question, or make mistake in the answer, or that you're dreaming, or hallucinating, or that you've momentarily forgotten that the question was preceded by "In base 4, what is ", or any number of other things that absolutely are possible, even if highly unlikely, in the real world.