What's the single best introduction to evolution to give to a creationist?

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.

Pointing out that she should give your arguments due consideration is not necessarily the best way to get her to do so. Here are some techniques I've found useful to avoid triggering defense mechanisms:

• Tone is important. Phrase your e-mail in a friendly, humourous and above all non-threatening manner. The Socratic method is well-suited here, as long as your questions come across as curious and playful rather than scathing and rhetorical.
• Focus on exciting and cool evidence, like this ring species business. Use vivid imagery, and encourage her to imagine and understand this happening. This might also allow you to exceed 3000 words without losing her attention.
• If you do address creationist counter-arguments, make sure that you (visibly) give her arguments due consideration. For example: "It certainly seems this way, but consider the following" rather than "No, that's just wrong, and here's why."
• Present strong evidence, but understate the conclusions. For example: rather than "God didn't have a hand in the origination of species", just say "If God created all life on Earth, he did it in such a way that it would look like evolution did it."
• Find a place of agreement. That is, find the last place in the debate where you both agree and where your beliefs begin to diverge; then proceed slowly from there. As I've said, tone is very important. This technique is more useful if you have an ongoing dialogue, but you should be able to adapt it to a one-off e-mail, if you have a reasonable estimate of where that last place of agreement may lie.

Don't think in terms of where you want her to end up. Work out where she is now, and present a position one inferential step away from her current position.

In my Intro To Logic class that I took a long time ago, the teacher led the class in a deduction about evolution. You could basically lead her through the deduction and invite her to poke at the premises, yourself, if you are confident enough talking about it. You could even sketch it out on a napkin in a restaurant. If my outline is insufficient, just let me know what I can do to help you flesh it out to your satisfaction.

1) Scarcity - there aren't enough resources for everybody to get all of what they need/want. (In my experience, some Christians deny this, claiming god will provide. You could easily counter that if that were the case, there'd be no such thing as economics. Or point out that there's half a million people starving to death in Botswana who might disagree).

2) Variability - There's differences between individuals in a population (I haven't had any trouble with getting people to agree to this one).

3) Inheritance - Differences between individuals can be passed down to descendants (They might need a prod by saying that kids grow up to look like their parents, or something like that).

4) Because variability can be passed down to future generations (via 2 and 3), any variability that makes you better at getting a bigger slice of scarce resources gives you a better chance to have babies.

I know it isn't technically a deduction, since I didn't introduce every term and show how P1 & P2 => C1, etc, but I imagine formal logic isn't something your friend cares much about.

A biologist friend of mine has had limited success with this method. He has also suggested that the book "Why Evolution Is True" be read by novices who are open to actual dialogue but don't know enough to accept evolution.

There is another effective framing technique that I almost never see used that might be worth considering because I've seen it used well in the past.

Most people think evolution is a purely biological concept and it is virtually always framed in such ways. This runs headlong into the mystical beliefs many people attach to living organisms. Making evolution a property of an organism is no different than making a "soul" the property of an organism to them, and fits in the same cognitive pigeonhole. A lot of the jumbled chemistry and thermodynamic arguments follow from this as well; biology is special precisely because it can violate the laws of science.

Evolution is fundamentally a systems dynamic from mathematics. If you have a system -- any system -- with a certain set of abstract properties then there are certain required mathematical consequences. The result of 2+2 is always 4, no matter where in nature we find it. Biology is just one type of system to which this mathematics is applied; it has the prerequisite properties on the left hand side of the equation that require the system dynamic biologists call "evolution" on the right side of the equation. Mathematics asserts that evolution should exist in biology whether or not science has found evidence of it (fortunately, we have found much evidence). When evolution emerges from mathematics instead of biology, it has a sterilizing effect on the concept.

It turns out that very few creationists are willing to dismiss mathematics in the same way they dismiss science. Mathematics is neutral territory, it does not have a political or religious affiliation in the minds of most people, and almost everyone tacitly "believes" in it because they use it every day. The few times I have seen this strategy used -- completely divorcing evolution from science -- even the militant true believers found themselves at a loss for a counter-argument (not that it changed their minds).

I know you're looking for something shorter than book-length, but I've been scouring popular evolution books in hopes of presenting one to my creationist parents at some point. Here are some of the most popular:

Dawkins - The Greatest Show on Earth

Strengths: Sufficiently-technical but still simple explanations of how we measure genetic relatedness, the Lenski E. Coli study and its implications of intelligent design and historicity of mutation, how embryological development and "blueprints" (ie, Hox genes) factor into the big picture, the limits of evolutionary growth (in terms of marginal benefits and costs), "purpose" in evolution (very similar to An Alien God), and how fossils are dated.

Weaknesses: Pretty much everything else. Dawkins has a rambling writing style, focuses on controversies that are best left ignored when talking to someone who doesn't even understand the basics (ie, the exact origin of turtles), and spends a good portion of the book trying to lower the social status of creationists.

Coyne - Why Evolution Is True

Strengths: Absolutely the best explanation of the evidence for evolution from biogeography I have ever read. Since most creationists outright ignore this evidence, it will be surprising to the uneducated, and therefore more convincing. Good (but not great) explanations of how fossils are dated. This is the only book I've seen mention that radiometric dating has been verified by other methods (ie, fossil coral rings), which is another surprising argument that creationists usually ignore. Good, brief explanations of genetics and fossil evidence. Good explanation of vestigial organs and "bad design." Great chapter on sexual selection theory, its predictions, and its evidence.

Weaknesses: The focus of the book is definitely on facts that creationism can't explain, so every chapter has at least one moment of, "How can creationism explain this, except by pure ad-hoc?" This can come off as combative. Some of the scientific explanations are so simplified as to be nearly false--for instance, Coyne comes very close to implying that fossils must be sandwiched between two layers of igneous rock to be dated properly, when of course many situations (including an intrusion of igneous rock) will also do.

Prothero - Evolution: What the Fossils Say and Why It Matters

Strengths: Goes through most of the major transitional series, with pictures and diagrams, to show why they are best understood as transitional fossils. This includes series that creationists usually ignore, like the evolution of triceratops, long-necked dinosaurs, ichthyosaurs, brontotheres, "small shellies," early vertebrates, and several microscopic fossils. Great explanation of cladistics. Great chapter on the origin of life--instead of saying, "Evolution doesn't address that," Prothero takes the reigns and says, "Here's what we know, chemically, and here are the current working theories." Great chapter on the Cambrian explosion--which he calls the "Cambrian Slow Fuse," as he points to the 100 million years it took to go from small shellies to the worldwide proliferation of trilobites. For your purposes, there is a discussion of the compatibility of evolution with some religious views.

Weaknesses: Prothero is a student of Gould, so the book wastes a bit of time discussing (bad) philosophy of science, "separate magisteria," and punctuated equilibrium. (Not that there's anything wrong with punctuated equilibrium, but I think its presentation confuses the discussion in a way that would be better remedied simply looking at the charts presented in this video.) Prothero also spends some time gloating over one of his debates with Duane Gish. This is entertaining to someone already sold on what he's selling, but would be off-putting to a creationist.

If anyone has more recommendations, I'll check them out. I have yet to read Eugenie Scott's Evolution vs. Creationism: an Introduction, the NCSE's evolution primers.

All that it took to convince me, even while I was still a Christian, was two college-level geology courses and Talk Origin's Index to Creationist Claims, wherein I learned the tendency of creationist authors to lie, lie, lie, lie, lie.

The easies thing to do would be to give her a copy of TalkOrigins' Introduction to Evolutionary Biology. It's excellent, and not too long. It may overwhelm her, though, so if you'd like to write something of your own, I'll give some suggestions. I used to argue with creationists as a hobby, so this is kind of nostalgic for me.

What kind of creationist are we dealing with here? Is she a young-earth creationist who thinks the world is a few thousand years old, or an old-earth creationist who won't choke on basic geology? If she's an old-earth creationist, I would suggest reading up on a few fun geological processes that took longer than she thinks the earth has existed. One thing in particular to mention is how we do radiometric dating; a lot of creationists have this silly notion that we try to carbon date everything, no matter what the time-span, and that there's no corroborating evidence for any of it. With few exceptions, these people have never heard of things like potassium-argon dating or the geomagnetic polarity reversals that mark time on the sea floor. Or dendrochron calibration, or the passing of the seasons recorded in ice sheets. If your friend is a young-earther, infodumping about this stuff in a basic way should be moderately upsetting to her, in a good way.

General advice that applies to all kinds of creationists: if you're not going to be arguing back-and-forth with her, then you should try to make her feel doubt. For example, you could quote the head of the Human Genome Project, Francis Collins:

As someone who's had the privilege of leading the human genome project, I've had the opportunity to study our own DNA instruction book at a level of detail that was never really possible before.

It's also now been possible to compare our DNA with that of many other species. The evidence supporting the idea that all living things are descended from a common ancestor is truly overwhelming.

I would not necessarily wish that to be so, as a Bible-believing Christian. But it is so. It does not serve faith well to try to deny that.

But I have no difficulty putting that together with what I believe as a Christian because I believe that God had a plan to create creatures with whom he could have fellowship, in whom he could inspire [the] moral law, in whom he could infuse the soul, and who he would give free will as a gift for us to make decisions about our own behavior, a gift which we oftentimes utilize to do the wrong thing.

I believe God used the mechanism of evolution to achieve that goal. And while that may seem to us who are limited by this axis of time as a very long, drawn-out process, it wasn't long and drawn-out to God. And it wasn't random to God. [He] had the plan all along of how that would turn out. There was no ambiguity about that.

There are compelling arguments you could make against the idea of an intelligent designer shaping evolution -- the design mistakes, the existence of horrific parasites, the breathtaking cruelty of certain parts of nature -- but it would be a victory if you could just get this friend to admit that evolution happened at all, God-guided or otherwise.

Give her a glimpse of the mountain of evidence that she's denying. Talk about fossils, and mention the standard rebuttal to the "no transitional fossils" nonsense. Touch briefly on modern phylogenetics, reconstructing the tree of life by looking at patterns in the genes of living animals. Find some specific examples of coevolution between species, and exposit. Richard Dawkins' books tend to be excellent sources of detailed examples, presented with his usual cheerful enthusiasm; I recommend them.

TalkOrigins is a treasure trove. Some especially useful pages are their FAQ listing observed speciation events, and the list of crappy designs in nature. Also useful is creationtheory.org, which is more focused than TalkOrigins and an excellent resource. You might also try explaining why evolution does not violate the laws of probability, which is a very common creationist argument.

Good luck planting a seed of doubt. That's all you can realistically hope to do right now, so don't get discouraged if she doesn't change her mind right away.

Tangentially, the fact that she is arguing with a person that believes in evolution could itself be a problem that changes the dynamic.

I've often observed that most people believe in evolution in essentially the same way a creationist believes in creationism. They did not reason themselves into that position nor do they really understand evolution in any significant way, it was a position they were told all right-thinking people should believe and so that is why they do so. The charge often forwarded by creationists that evolution is merely another quasi-religious belief comports with reality in many cases, unfortunately. Nominal evolutionists that are clueless about evolution and just parrot talking points can often destroy the credibility of scientific evolutionists that come later.

Understanding the qualifications of the person she is having a discussion with is helpful from a tactical standpoint -- it determines the nature of the defense of creationist ideas.

Being a veteran of many creationist arguments, I would make the point that there is no need or reason to bring religion into it nor even to talk about "losing an argument". You can ignore it entirely if you choose to and it usually keeps the defensiveness down. Also, stay away from any arguments that have well-known creationist defenses; it will force her to think about what you are saying rather than giving the opportunity to borrow what someone else has said. Keep the tone matter of fact so that it doesn't sound like you have an emotional investment in it -- very important. If you really want to play it clean, don't even frame it in terms of what you think or believe; just discussing chains of reasonings over reasonable facts without inserting a value judgement helps make the other party think they are reasoning to the conclusion themselves rather than you imposing your beliefs.

Most of the work is framing. If you make it completely orthogonal to what anyone believes, religious or otherwise, and turn it into an emotionally-neutral logic puzzle, you can often bypass the memetic defenses long enough to make a difference. It does not matter what you believe if we have this interesting set of scientific facts...

If she actually accepts "microevolution":

http://en.wikipedia.org/wiki/Ring_species

But if she brought me this request as written, I'd go on to ask what questions she has about evolution. Gently remind her that I may have only thought about these questions once, and even biologists rarely spend much time thinking about creationism after accepting what they consider the truth. If she wants an answer of less then book-length, we might need her to remind us where we needed evidence to persuade us.

I was at her house tonight. I asked a few probing questions to get a framework of what I'd say:

1) How old do you believe the earth is (her answer was something like a few million, which seemed pretty arbitrary to me but which was apparently based off of a particular argument she'd read)

2) Do you believe in microevolution? (the answer is yes, but not because of knowledge of evolution - it's because of the practicality of fitting all the animals onto the ark. Two of each "platonic" animal that then evolved into similar things)

3) What exactly do you want to know? (the answer was "enough background knowledge so that when she goes to argue with her friend she'll know what she's talking about." But she also was genuinely interested in having some conversations with me about it, just to get a better understanding of what I believe and why)

4) Could you think of any circumstances that might change your position on macroevolution?

The answer was no.

After a quiet mental facepalm, I steered the conversation towards the ability to change our minds and hard but necessary an ability it is. I don't think this was necessarily optimal, but past experience has taught me that when I hear a creationist make that kind of statement, I know that the discussion is already over - anything else we say is just for fun. Her answer was consistent an unapologetic: "The only way to change what I believe is to prove that Jesus wasn't the son of God."

A lot of people recommended simply stating the facts. I think you really grossly underestimate how much bias at work here and how non-obvious your interpretations are to someone with no scientific training. We didn't have internet so I wasn't able to grab a reference to transitional fossils. I'll be linking her to Talk Origins. (Rereading it, I was almost surprised at how good a reference it was. I had forgotten. But it's a little intimidating to just throw at someone).

We did have a good long conversation, which I considered somewhat productive. It ended up focusing more on the Bible than on evolution. She seemed less confident towards the end. (She kept saying stuff like "Josephus is an independent historian who mentions Jesus" and I said "yeah but his testimony came 100 years later and basically carries no wait" and she said "no.... lemme look it up... oh... huh"). Past experiences suggest that these temporary lapses in confidence will be repaired within a few days.

Eventually the conversation turned back towards evolution, and I ended with the "math and genetics" angle, but by then she was tired and I think I wasted the moment.

I still feel like there needs to be a Pro-Evolution book that very carefully unpackages it in a way that doesn't automatically set off a creationist's memetic immune system. (I'll check out Why Evolution is True and see if it comes close). I actually think I'm pretty good at that, but I'm not a biologist and I don't care enough to do all the research necessary to write an all encompassing book.

Explain a bit of how genetics works, then mutation, then heredity, then selection, then show how the combination causes evolution.

This is a lesson from my 10th grade biology class:

Take a bunch of marbles with two different colors. (Lets say blue and white)

Explain that these are the possible alleles in the population, with blue coding for hair and white failing to code for hair.

If a rabbit inherits any blue marbles, it has hair. If it has only white marbles, it isn't born with hair. White marbles represent recessive alleles, but that's not particularly important to evolution.

Now mix all the marbles up in a bag/hat/whatever and draw them two at a time. This produces one rabbit. Write down what that rabbit's traits are. The mixing and drawing represents random mating, saying that all the living rabbits have 2 children, with randomly selected other rabbits. These assumptions aren't accurate, but evolution will still be demonstrated when...

You draw out all the marbles and produce a generation of rabbits. Now say that the winter was really cold and killed all the hairless rabbits. Remove all the pairs of marbles which are all white.

Mix marbles, repeat, take note. Explain that the white alleles are being selected out of the population.

Now just say that surviving rabbits will consume resources to make up for the deaths of the white ones, or not. This basically just demonstrates that a selection pressure will remove deleterious genes from the population.

It will still probably take work to explain that mutations will lead to different traits which are then selected for.

It seems like a good opportunity to broaden someone's mind in a more general way that'll benefit them in the long term. ... But I'd like to phrase my e-mail in a way that's most likely to cause her to re-evaluate her worldview.

The best way to convince her might be not to try to convince her at all. Just give her exactly what she's asking for -- the straight theory of natural selection in a convenient, readable form. Your secret ace in the hole is that it's the truth. If she is willing to understand the theory, then reasons to accept it as true are everywhere. All of biology is linked to evolution, including the forensic DNA evidence that they talk about on CSI.

I realized that I left some information too vague. I had been trying not to go too much private conversation on a public board. I edited my initial post to clarify my goals a bit.

1. 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).

I can see why this is useful as a rhetorical trick but I don't see how you can argue for compatibility without twisting evolution. All of the core elements, both historical and metaphorical, of the story of Original Sin run counter to actual fact.

beriukay's post below seems like a good place to start. I might stress that evolution is inherently a bottom-up phenomenon: there are a few guiding principles that make sense, and if you accept the principles in one region then they can apply in every region and explain everything. 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. If wing color can be changed by mutation, then why not embryology?

http://lesswrong.com/lw/kr/an_alien_god/

There are a few demos which use genetic algorithms to demonstrate various evolutions.

A few caveats with each of them, but the basic selection effect is conveyed.

I'd just send her a link to the harvey birdman episode. At least it's amusing.

http://video.adultswim.com/harvey-birdman-attorney-at-law/evolutionary-war.html