Nov 082011
 

I was feeling smugly knowledgeable and clever, and then I started reading Stephen Hawkings’ Grand Design. I understand, oh, maybe half of it? He loses me at field theories.

But there’s one bit that I found to be a wonderfully clear description of something that I’ve struggled to make clear.

In 1922, a Russian mathematician named Friedman found the galaxies are moving away from each other, and he did it by making two assumptions:

…[T]hat the universe looks identical in every direction and that it looks that way from every observation point. We know that Friedman’s first assumption is not exactly true. The universe fortunately is not uniform everywhere. If we gaze upward in one direction, we might see the sun, in another the moon or a colony of migrating vampire bats. But the universe does appear to be roughly the same in every direction when viewed on a scale that is far larger – larger even than the distance between galaxies. It is something like looking down at a forest: if you are close enough, you can make out individual leaves, or at least trees and the spaces between them. But if you are so high up that your thumb covers a square mile of trees, the forest will appear to be a uniform shade of green. We will say that, on that scale, the forest is uniform.

And what good could come from making such a sweeping assumption that wipes out every variegated leaf, every inch of bark, every mammal and bird and lizard the dwelled there? Why, this:

Based on his assumptions, Friedman was able to discover a solution to Einstein’s equations, in which the universe expanded in a manner that Hubble would soon discover to be true.

Which is, ya know, IMPORTANT.

And it just doesn’t matter if there are a million brown monkeys living in the forest; it’s still true that from space, the forest is green.

Ya’ll know that my my dissertation looked specifically at interactions across levels of analysis, so this question of “scale” is very, very important to me, particularly as it relates to sex research.

Many of you will consider me embarrassingly naive when I say that I was surprised, when I talked about things that are true about populations – for example, that human populations contain two general categories of people, males and females – that people reacted negatively.

And by “negatively,” I mean people felt personally insulted, “erased,” oppressed, and generally like the scientific establishment was deliberately trying to tell them they don’t exist.

Truly, I was like, “… Huh?”

Because I know that science about populations has no particular meaning for individuals. Like: On average, humans are 5’6″, brown-eyed, and east Asian. Should I therefore think, “Phew, I’m 5’6″, but crap, I’ve got blue eyes and I’m this northern European mutt! There’s something wrong with me!” No.

Or should I think, “I’m not brown-eyed and I’m not east Asian, so therefore that’s BULLSHIT!” No. It’s not bullshit just because it’s not true about ME; it’s not TRYING to be true about me, it can only be true about the POPULATION.

No, the sentence, “On average, humans are 5’6″, brown-eyed, and east Asian,” is both true and fair. FROM SPACE (according to the metaphor). At the largest scale.

What’s not true is, “Every individual human who ever existed was 5’6″, brown-eyed, and east Asian.” At the human-level scale, that’s simply wrong.

And making a LAW that says, “People are 5’6″, brown-eyed, and east Asian; to be anything else is against the law,” is both untrue and unjust – a.k.a., ACTUAL “bullshit.”

And I want everyone to be able to tell the difference between those things, between science, what’s true about you, and bullshit.

The basic point that something can be true about the population you live in without being true about you as an individual is something I’ve struggled over and over to persuade people to take for granted, even to the point of considering giving up on the idea.

Social science at the population level is an important reality-check, bringing us out of our on-the-ground perceptions and lifting us into orbit to see the bigger picture. The bigger picture is powerful and important. Each of our little micro-pictures also is important, in different ways and for different reasons. And science at the population level is NOT a weapon; it’s a tool. As the Dog Whisperer tells us, “It’s not the tool, it’s the person holding the tool,” that makes it a weapon.

(I wonder if we could train all journalists writing about science to include not only the means but the variability, just to help remind people that the very concept of “average” necessarily implies variability.)