In light of recent events, I’d like to explain Bastiat’s parable of the broken window in a more, shall we say, econometric format.
Using the standard definition of GDP (“the total market value of all goods and services produced within an area in a given period”), we can measure the GDP of a fictional village in France called Parableville. In this village, James Goodfellow’s window has just been broken by his careless son. He will now pay the glazier six francs to get his window replaced. This expenditure is added to Parableville’s GDP. Assuming the GDP for the previous period was 100 francs, then the GDP for this period (ceteris paribus) will now be 106 francs. That’s an increase of 6% in GDP for Parableville. Clearly breaking windows can lead to increased GDP.
However, as Bastiat noted, there’s what is seen and there’s what is unseen. What’s unseen here? James Goodfellow’s loss, of course. Since he paid six francs to the glazier to make a new window for him, we can estimate the current market value of his old window as also being six francs. If we offset this loss against the new window, we find that (again ceteris paribus) the GDP for Parableville stays at 100 francs. In other words, when we take economic losses into account, breaking windows doesn’t lead to increased GDP.
There’s more to this story, though. Let’s now say that, had James Goodfellow’s window not been broken, he would have paid the cobbler for a new pair of shoes. Let’s further suppose that James would have paid the cobbler six francs for this. Doing so would also raise the GDP for Parableville to 106 francs (again ceteris paribus), but this time there’s no accompanying loss, so the GDP value stays there. Compared to the “seen” GDP, this “unseen” GDP is 6% higher. Inverting this, we can say that breaking the window resulted in a “seen” GDP figure that is 6% lower than the “unseen” figure.
Now let’s change the scenario to something a bit more modern. Let’s say that the government of Parableville takes six francs from James Goodfellow in taxes. It then spends that six francs on a new window from the glazier. Following the definition of GDP, this would raise Parableville’s GDP from 100 francs to 106 francs (ceteris parabus). Once again, however, this doesn’t take into account the loss against James Goodfellow, which is also six francs (the amount he was taxed). Offsetting this loss, and holding to ceteris paribus, brings the GDP back down to 100 francs.
Had the government of Parableville not taxed those six francs from James Goodfellow, he would have used them to pay for a new pair of shoes from the cobbler, as before. Once again, there would have been no offsetting loss here, so Parableville’s GDP would have genuinely grown by six francs, or 6% over the previous period’s GDP value of 100 francs (again ceteris paribus). The inverse of this is again that taxing six francs from James Goodfellow resulted in a GDP figure that’s 6% lower than what it otherwise would have been.
So we can see that taking into account offsetting losses would be a significant step in making GDP more accurate. Not only that, but doing so could also give us at least an idea of how much more the GDP would have grown had those offsetting losses not occurred. To sum up, the GDP measure as used by econometricians the world over in no way accounts for all of the effects of “broken windows”.