The principle of indifference states that,

> 
> In the absence of any relevant evidence, agents should distribute their credence (or 'degrees of belief') equally among all the possible outcomes under consideration.
> 
> 
> 

This means that two individuals with different amounts of "evidence" can come up with two different probabilities - that is, probabilities can be subjective. I can't think of a case where subjective probabilities might be useful in predicting the future. For example, say I have a biased coin that's biased towards heads but I do not know that it's biased and so I assign the probability of heads and tails to be both $\frac{1}{2}$. But this probability distribution will be useless in predicting the future as in the long run, I will end up with more heads than tails since the coin's biased towards heads. I was wondering what are some examples of when subjective probabilities might be useful?