Are credences in between 0 and 1?

The idea behind credences is that, while I believe both that 2+2=4 and that it will be sunny tomorrow, I have far more certainty in the former than the latter. This level of certainty is measured in terms of your credence in a proposition. These are numbers that can take a value between 0 and 1, with 0 being certainty that the proposition is false, and 1 being certainty that the proposition is true.

I think this is an inaccurate way to frame credences though. Imagine a man who is happy. Then he gets happier and happier. Is there a limit to his possible happiness? It doesn't seem there is. Maybe there's a limit for his current brain, but we can also imagine his brain being regularly modified so he can continue to get happier and happier.

If we can do this with happiness, then why couldn't we do this with a feeling of certainness? If this is possible, then it doesn't seem to make sense to represent all of our feeling of certainness as values in between 0 and 1. It seem certainness should be any real number.

An alternative way of looking at this is that happiness can also be assigned values in between 0 and 1. This would lead to an interesting new kind of mathematical systemization of happiness. If p corresponds to a happiness of 0.3, and q corresponds to happiness of 0.7, what happiness would be dealt by the conjunction of p and q? Or what about their disjunction?