I'm about to rewrite the section on the is-ought gap, for clarity, so here's a copy of the original text:

Many claim that you cannot infer an 'ought' statement from a series of 'is' statements. The objection comes from Hume, who wrote that he was surprised whenever an argument made of is and is not propositions suddenly shifted to an ought or ought not claim without explanation.

Many of Hume's followers concluded that the problem is not just that this shift happens without adequate explanation, but that one can never derive an 'ought' claim from a series of 'is' claims.

But why should this be? If someone makes a claim of the 'ought' type, either they are talking about the world of is, or they are talking about the world of is not. (What they're talking about is plausibly reducible to physics, or else it isn't.) If they are talking about the world of is not, then I quickly lose interest because the world of is not isn't my subject of interest. If they are making a claim about the world of is, then I ask them which part of the world of is they are discussing. I ask which ought-reductionism they have in mind.

Often, they have in mind a common ought-reductionism known as the hypothetical imperative. This is an ought of the kind: "If you desire to lose weight, then you ought to consume fewer calories than your burn." (But usually, people leave off the implied if statement, and simply say "You should eat less and exercise more.")

A hypothetical imperative (a kind of ought statement) reduces in a straightforward way to a prediction about reality (a kind of is statement). "If you desire to lose weight, then you ought to consume fewer calories than you burn" translates to the claim "If you consume fewer calories than you burn, then you will (or are, ceteris paribus, more likely to) fulfill your desire to lose weight."

Or, perhaps someone has a moral reductionism in mind during a particular use of 'ought' language. Perhaps by "You ought to be more forgiving" they really mean "If you are more forgiving, this is likely to increase the amount of pleasure in the world."

As you can see, it is not hard to bridge the is-ought gap. 'Ought' statements either collapse into the world of is (as with hypothetical imperatives or successful moral reductionisms), or else they collapse into the world of is not (as with Craig's moral theory of divine approval).