The question on Quora was: Can someone, preferably a biologist, give me a contemporary definition of evolution, as it appears to change so greatly among scientists, particularly when evolution is challenged?

My answer was:

A trait of non-scientists is that they get frantically obsessed with definitions, rather than reality.  In fact, they tend to confuse definitions with reality, as if words had some magical power over the world.

We see this on Quora with the constantly repeated questions about “What is a species?” and “Is a virus alive?” — questions that are almost entirely pointless scientifically.  A species is whatever you want to call a species; that doesn’t change what’s out there.  A virus is whatever it is; it doesn’t change when someone tries to squeeze a word into it.

It’s a mark of someone who doesn’t actually understand science that they want definitions — perhaps because they think that words have power, and gives them control over the world.

Scientists aren’t completely indifferent to definitions, but mainly because it lets them talk amongst themselves.  Scientists don’t give a shit that there are twenty or thirty definitions of “species”, some of which are mutually exclusive.  They can natter about whether a virus is alive or not (so I’m told; I’ve never heard any virologist actually ask the question, myself), but it would never occur to them to do anything differently because of the definition.

The only real definition of “evolution” is a map with a scale of 1:1.  Evolution is what evolution is.  Trying to define it is a parlor game, like coming up with names for collectives of animals.  It’s great to know that a group of crows is a “murder”, but it doesn’t change a damn thing about the crow.  It might make you feel better to decide that evolution is a change in the frequency of alleles among a population, but it doesn’t change a damn thing about the population.

A definition of “automobile” is “a passenger vehicle designed for operation on ordinary roads and typically having four wheels and a gasoline or diesel internal-combustion engine.” Another definition is “a vehicle used for carrying passengers on streets and roads“.  Exactly how much time do you think the nice people at Ford or Mercedes spend thinking about these definitions? How much difference do these definitions make to their work? Both of these definitions seem to exclude off-road vehicles; do you think the management of Chrysler finds this worrisome, and holds regular meetings to bring their Jeep division into line? Because that’s just about the level of importance that scientists put on definitions of “evolution”.

If you’ve been confused about definitions of evolution, this is probably why – you’re asking scientists to play parlor games that they don’t really care about.  If you’re trying to understand evolution with a tidy, succinct definition, it’s proof that you don’t understand anything about evolution to start with.

In a response to a comment, I added:

I think you’ve put your finger on why people want definitions for evolution: “For legal purposes, for instance”.

Notoriously, “for legal purposes” is pretty much the opposite of looking for reality; when you start talking about “legal purposes”, you’re talking about ways to subvert the truth, to evade or distort the truth for your own purposes.

The people who insist on getting definitions for evolution aren’t trying to understand it; they’re looking for ways to pretend they don’t understand it, to use weasel words and bafflegab to try to make truth look false, to distort, to get as close as they can to outright lying as they can while being able to pretend they’re not really lying.

If you want to go and sue evolution, then definitions are about your only hope.  If you’re actually trying to understand evolution, definitions have pretty much no interest for you.

The legal department at Crysler may well be deeply interested in the definition of “automobile.  Meanwhile, down in the engineering department, the people who are actually contributing to the world instead of trying to distort and profit from it aren’t interested at all.

Thanks for the clarifying insight.