If by chance you don’t frequent the geekier side of the twitterverse you might have missed the outpouring of wit-in-140 that followed this post by Gene Marks

If I was a poor black kid I would first and most importantly work to make sure I got the best grades possible. I would make it my #1 priority to be able to read sufficiently.   I wouldn’t care if I was a student at the worst public middle school in the worst inner city.  Even the worst have their best.  And the very best students, even at the worst schools, have more opportunities.  Getting good grades is the key to having more options.  With good grades you can choose different, better paths.  If you do poorly in school, particularly in a lousy school, you’re severely limiting the limited opportunities you have.

As it so happens I was a poor black and I built a rational expectations model of the very phenomenon Marks describes.

I look back on it and I see how it was the origin of the Smithian worldview I push today.

The problem is this: You want to build a model of the choices facing a poor black kid in a bad environment. You need to sketch out a decision tree and then turn that into a choice function and then – in my case – simulate the interaction between neighborhoods and student choice on a computer.

Significant insight can be gleaned from the closed form solutions but to really watch the magic you need numerical estimation.

In building this model one thing became glaring clear. The life choice that Mark’s outlines and that is advocated as prudent and reasonable by society is in fact incredibly risky.

I probably can’t convey the view-quakiness of this revelation because its now so entwined with the way I see the world. However, imagine the choice of a poor teenage girl deciding whether or not to have unprotected sex and possibly become pregnant, or to study hard, make good grades and stay in school.

Forget the unprotected sex itself, which we almost all find enticing.

The key is the pregnancy. For a 16 year-old girl regular unprotected sex will result in a full term pregnancy in the modern world with roughly probability one. There is little chance she will die in child birth. Late term miscarriages at her age are rare.

Now, just like any other parent the birth of that child will be the most important event in her life. And, the love of that child will be the most valuable thing she experiences. Some people say that looking back their career was more important than their children, but those people are few and far between.

So, if the girl has unprotected sex she gets right here, right now, the most important and valuable thing in life will happen immediately with PROBABILTY ONE.

Its difficult to get better than that. Waiting at all creates a risk that something will happen to prevent this. Even, if you can be sure it won’t – and many couples find out unfortunately that you can’t be so sure – you still have to discount the time. You have wait for the most valuable thing in your life.

Mark’s would have her set all that aside. Put away time that she will never get back – you must remember that no matter what you will never get these days back – for the chance that supposedly she will go on to college and get some job and meet some guy and then later have a different child under what might be better circumstances.

This is a risk. Taking Marks advice means that you lose a sure shot at the greatest thing in life. It means that you potentially waste time and time is the currency of life. He wants to convince you that the gamble might pay off.

Yet, how is a Bayesian supposed to tackle this problem?

I look around in my neighborhood and by definition none of the folks here have done what Marks suggests. These people are like me. I have no reason to believe that I am different.

What kind of sense would it make for me to take this gamble when no else does? No, it makes more sense to play it safe and take the sure thing.

Now, of course teachers, parents and helpful people like Marks will tell me to do otherwise. Should I believe them?

Not on your life.

By their own admission they want to see me “succeed.” That is, they benefit from my gamble. Yet, they incur none of the risks. They don’t lose time with their child. They don’t risk their fertility. They don’t experience the disutility of social climbing.

Heads they win. Tails I lose.

Listening to them would be nothing short of foolish.

And, so of course the teenage girl does not listen. Not because she is irrational, but because she is rational.

Indeed, strategies to get her to change her mind hinge on coercion or leveraging irrationality. Parents may threaten as poor parents do not have the resources to bribe.

Some teachers will try to convince students that they can do anything if they try. Clearly they can not. Others will significantly downplay the disutility of social climbing. They will cast crossing into the cultural unknown as uplifting, not depressing and possibly deeply lonely. These kind of stories border on outright deception.

Everyone will try to get her to “believe in herself.” This is an attempt to induce Caplan-esque rational irrationality. That is, to attach an emotional preference to a belief about the natural world. This is epistemologically equivalent to the nationalistic fervor that accompanies “America First.”

And, if that doesn’t work some teachers will resort to honest guilt: “We took a chance on you, now you take a chance on yourself.”

However, all of these strategies come down not to encouraging prudence and rationality, because the prudent and rational thing to do is to get pregnant. They instead hinge on emotional appeals to irrationality, noble lies and social, and sometimes physical coercion.

If you were a poor black kid, that’s what you would face.