Once you buy that microevolution can happen with moths and wing colors, and understand the two forces of mutation and natural selection, then you have to buy that macroevolution can happen.
When talking about convincing creationists, I think it's valuable to taboo the phrase "have to" in the sense that you use it here. It might be a normative fact that, once you buy microevolution, you "have to" buy macroevolution. But it is definitely not an established empirical fact about human psychology that buying microevolution is inevitably followed by buying macroevolution.
The goal here isn't to discharge some obligation to give her information that "ought" to convince her, normatively speaking. The goal is to actually convince her. So claims about what "you have to buy" are only relevant insofar as they reflect what actual humans really do buy in actual fact.
Totally correct. But I think that's the right avenue to argue- not "haha, I tricked you into accepting A, now you must accept B!", but "these phenomena- evolution of individuals and evolution of species- are the same underneath the hood. The only change is this superficial one, from changing gene expression in adults and gene expression in embryology / chromosome creation."
I have a creationist friend with no particular rationalist or scientific training. She recently asked me to send her a "list of evidence for evolution that persuaded me." After some prodding, it was revealed that she's getting into an argument with another friend of hers who believes in evolution. I'm assuming that she wants the experience of arguing with someone who's on level footing with her. It seems like a good opportunity to broaden someone's mind in a more general way that'll benefit them in the long term. I don't particularly care whether she believes in evolution (it probably will not impact her or the world in general if she changes her mind about it). But I'd like to phrase my e-mail in a way that's most likely to cause her to re-evaluate her worldview.
Subgoals related to this:
1. Point out that "losing" an argument can allow you to learn things, and if you honestly care about truth you'll try your best to evaluate ideas from other points of view and consider what it would mean if they were true. Do this without sounding condescending.
2. Give her a line of retreat by proposing that evolution is compatible with the Original Sin interpretation of genesis (which is very important to her and I would never attempt to argue against).
3. Give as much background as possible on the scientific method.
4. Still manage to focus the bulk of the e-mail on the most persuasive facts supporting evolution, otherwise I'm obviously not satisfying the criteria she actually gave me. I don't mind taking advantage of her request for my own purposes, but only if I'm actually helping her with her stated goal.
5. Specifically show why macroevolution is not only possibly but likely. (I'm pretty sure she either already believes or could be easily persuaded to believe in microevolution)
6. DON'T focus too much on why creationist arguments are flawed (she hasn't even used any yet, and it sends the wrong message about trying to actually figure out what the truth is)
7. Accomplish everything in approximately 3000 words, without using jargon, designed to be read by someone who's mental architecture isn't particularly adapted to rationalist thinking. (Most people aren't.)
I believe I can do a decent job myself. But it'll be a fair amount of work, and I want to know if anyone had a recommendation for a particularly good essay that I can either link her to or borrow pieces from. I might also include a link to a page of common bad creationist arguments and why they don't make sense.