 The sum function is an interesting measure in its own right. While, like average, it is sensitive to the distances of all worlds in a proposition from the actual world, it is not plausible as a measure of distance from the truth, and indeed no one has proposed it as such a measure. What sum does measure is a certain kind of distance-weighted logical weakness. In general the weaker a proposition is, the larger its sum value. But adding words far from the actual world makes the sum value larger than adding worlds closer to it. This guarantees, for example, that of two truths the sum of the logically weaker is always greater than the sum of the stronger. Thus sum might play a role in capturing the value of content for truths. But it also delivers the implausible value of content for falsehoods. If you think that there is anything to the likeness program it is hardly plausible that the falsehood \({\sim}h \amp{\sim}r \amp{\sim}w\) is closer to the truth than its consequence \({\sim}h\). Niiniluoto argues that sum is a good likeness-based candidate for measuring Hilpinen’s “information factor”. It is obviously much more sensitive than is max to the proposition’s informativeness about the location of the truth.