 They only provide a lower bound for the probability of the conclusion (given the probabilities of the premises). In a sense this is the most important bound: it represents the conclusion’s probability in the ‘worst-case scenario’, which might be useful information in practical applications. However, in some applications it might also be informative to have an upper bound for the conclusion’s probability. For example, if one knows that this probability has an upper bound of 0.4, then one might decide to refrain from certain actions (that one would have performed if this upper bound were (known to be) 0.9).