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Mon, May 26, 2008 - Page 9　News List

Smith’s invisible hand is shaking

While the idea of selfish individuals unwittingly helping is popular, it doesn’t always work


Adam Smith’s modern disciples are far more enthusiastic about his celebrated invisible-hand idea than he ever was. In their account, Smith’s assertion was that purely selfish individuals are led by an invisible hand to produce the greatest good for all. Yet Smith himself was under no such illusion.

On the contrary, the relevant quotation from his Wealth of Nations, which describes a profit-seeking business owner, is far more circumspect. It says that this owner “is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention.”


In short, Smith understood that the invisible hand is often benign, but not always.

This understanding has important implications for economic policy in general, and for the recent presidential campaign dust-up about gasoline taxes in particular.

If you believe, with Smith’s modern disciples, that unfettered pursuit of self-interest always promotes society’s interests, you probably view all taxes as a regrettable evil — necessary to pay for roads and national security, but also an unwelcome drag on economic efficiency. The problem, according to this view, is that taxes distort the price signals through which the invisible hand guides resources to their best destinations.

Smith’s more nuanced position supports a different view of taxes. When market prices convey accurate signals of cost and value, the invisible hand promotes the common good. But prices often diverge from cost and value and, in those cases, taxes can actually help steer resources toward more highly valued uses.

It’s helpful to look more closely at why the invisible hand works so well in many ordinary markets.

Consider the market for potatoes: In it, production and consumption are determined by millions of separate cost-benefit calculations. Profit-seeking sellers are willing to offer an additional kilogram of potatoes for sale whenever the benefit of doing so — as measured by what buyers are willing to pay — is enough to cover the cost of production.

The market reaches equilibrium when the cost of producing the last kilogram is exactly equal to its value. If the costs incurred directly by sellers are the only relevant costs of expanding potato production, and if the benefits to potato buyers are the only relevant benefits, the invisible hand gets things just right.

The production and consumption of many other goods, however, generate costs or benefits that fall on people besides buyers and sellers. Producing an extra liter of gasoline, for example, generates not just additional costs to producers, but also pollution costs that fall on others. As before, market forces cause production to expand until the seller’s direct cost for the last unit sold is exactly the value of that unit to the buyer. But because each liter of gasoline also generates external pollution costs, the total cost of that last gallon produced is higher than its value to consumers.

The upshot is that gasoline consumption is inefficiently high. Suppose that pollution costs are US$0.50 for the last liter consumed, but that its US$1 price at the pump is just enough to cover its direct production costs. Reducing production and consumption by a liter would then cause consumers to lose fuel that they value at US$1, which would be exactly offset by the US$1 in reduced production costs. The US$0.50 in reduced pollution costs would thus be a net gain for society.

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