In population ethics...

Most people start out believing that the following are true:

1. That adding more happy lives is a net positive.
2. That redistributing happiness more fairly is not a net negative.
3. That the repugnant conclusion is indeed repugnant.

Some will baulk on the first statement on equality grounds, but most people should accept those three statements as presented. Then they find out about the mere addition paradox.

Someone who then accepts the repugnant could then reason something like this:

Adding happy people and redistributing fairly happiness, if done many, many times, in the way described above, will result in a repugnant conclusion. Each step along the way seems solid, but the conclusion seems wrong. Therefore I will accept the repugnant conclusion, not on its own merits, but because each step is clearly intuitively correct.

Call this the "differential" (or local) way or reasoning about population ethics. As long as each small change seems intuitively an improvement, then the global change must also be.

Adding happy people and redistributing fairly happiness, if done many, many times, in the way described above, will result in a repugnant conclusion. Each step along the way seems solid, but the conclusion seems wrong. Therefore I will reject (at least) one step, not on its own merits, but because the conclusion is clearly intuitively incorrect.

Call this the "integral" (or global) way of reasoning about population ethics. As long as the overall change seems intuitively a deterioration, then some of the small changes along the way must also be.

In general...

Now, I personally tend towards integral rather than differential reasoning on this particular topic. However, I want to make a more general point: philosophy may be over dedicated to differential reasoning. Mainly because it's easy: you can take things apart, simplify them, abstract details away, and appeal to simple principles - and avoid many potential biases along the way.

But it's also a very destructive tool to use in areas where concepts are unclear and cannot easily be made clear. Take the statement "human life is valuable". This can be taken apart quite easily, critiqued from all directions, its lack of easily described meaning its weakness. Nevertheless, integral reasoning is almost always applied: something called "human life" is taken to be "valuable", and many caveats and subdefinitions can be added to these terms without changing the fundamental (integral) acceptance of the statement. If we followed the differential approach, we might end up with the definition of "human life" as "energy exchange across a neurone cell membrane" or something equally ridiculous but much more rigorous.

Now, that example is a parody... but only because no-one sensible does that, we know that we'd lose too much value from that kind of definition. We want to build an extensive/integral definition of life, using our analysis to add clarity rather than simplify to a few core underlying concepts. But in population ethics and many other cases, we do feel free to use differential ethics, replacing vague overarching concepts with clear simplified versions that clearly throw away a lot of the initial concept.

Maybe we do it too much. To pick an example I disagree with (always a good habit), maybe there is such a thing as "society", for instance, not simply the total of individuals and their interactions. You can already use pretty crude consequentialist arguments with "societies" as agents subject to predictable actions and reactions (social science does it all the time), but what if we tried to build a rigorous definition of society as something morally valuable, rather than focusing on individual?

Anyway, we should be aware when, in arguments, we are keeping the broad goal and making the small steps and definitions conform to it, and when we are focusing on the small steps and definitions and following them wherever they lead.