The marginal utility of sin

Garett Jones, macroeconomist at George Mason University, has an interesting Twitter feed (follow him @GarettJones) where he poses macroeconomic questions, which are frankly often difficult enough, within the 140-character limits of Twitter. This usually results in a sort of riddle and, like most riddles, thinking through his riddle is often more important than simply knowing the answer.

Yesterday he posted an interesting remark:

Some pundits are like preachers, telling the faithful to avoid all sin. Good advice as long as benefits of sin equal zero.

I don't know too much about pundits, but I know a few things about preachers and sin and I think this statement is fascinating. Indeed, I think it captures well what is so hard to grasp about religion and the religious faithful (or unfaithful), but to understand this it may be useful to step into economic theory.

I think Mr Jones' comments regarding sin are a matter of marginal utility. Marginal utility is simply the benefit (or loss) resulting from a change in production, but that definition may not make much sense on the surface. It's more important to understand what marginal utility tells us--whether we should produce more or less of a product.

To put this in concrete terms, if you are buying an LCD TV (a purchase of $1,000 to $2,000 for most people) then you will do some research. You may spend 5 or 6 hours online or in showrooms or watching friends' TVs to get an idea what you need or want to purchase. Then you may spend another 1 or 2 hours driving to different shops to find the best price. Then you may spend another 1 or 2 hours online trying to save another $10 or $20 off the price. But at some point you will quit researching because even if you save another $1, you've decided it just isn't worth your time.

That's marginal utility. You're making a decision regarding production (TV research) based on the marginal utility (+$20/hour decreasing to +$1/hour in my example.) When marginal utility = $0, you know to stop production (or stop wasting your time); that's how it works, more or less.

So what has this got to do with religion and sin?

Some pundits are like preachers, telling the faithful to avoid all sin. Good advice as long as benefits of sin equal zero.

What are the benefits of sin? Well, to the consumer (or the faithful, in this case), there is a calculation of marginal utility (marginal cost of being faithful?) whereby the faithful consumer decides whether the production of abstinence or the production of indulgence produces more utility. If abstinence results in +$0 utility and sin results in +$5 utility, choose sin (you've had your fair share of avoiding sin, since utility is $0, so go ahead and grab some more sin, which seems to still profit you.)

I think that's a fair model for the way most of the faithful (or unfaithful) consumers of religion think. Certainly, if any of the faithful consider avoidance of sin to always produce a benefit of +$0, these may think of the production of sin as their primary concern until it has +$0 utility. At that point should they consider avoidance of sin to be worthwhile.

Of course, thinking this way seems to neglect the benefits (utility) of avoiding sin and I think any good preacher should tell you there are many. But I guess that's a difference between the role of the economist and preacher. The economist tweets to describe what the model is (positive economics, what's actually happening) while the preacher tweets to tell you what the model should be (normative economics, what should be happening.)