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In some ways, economics is like medicine two centuries ago. If you were ill at the beginning of the 19th century, a physician was your best bet, but his knowledge was so rudimentary that his remedies could easily make things worse rather than better. And so it is with economics today. That is why we economists should be sure to apply the principle “first, do no harm.”
This principle suggests that when people have voluntarily agreed upon an economic arrangement to their mutual benefit, that arrangement should be respected. (The main exception is when there are adverse effects on third parties — what economists call “negative externalities.”) As a result, when a policy is complex, hard to evaluate and disruptive of private transactions, there is good reason to be skeptical of it.
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