"When goods don't cross borders, armies will."

That famous aphorism summed up the free trade argument of French economist Frederic Bastiat. It's a wise saying. When trade is managed with high tariffs and prohibitions, the politics of us versus them cascades in such a way that the aligned enemies find themselves preparing -- and then actually going -- to war.

Thus the dangers of managed trade.

But the reverse is also true: "When we have enemies but nevertheless keep our armies from crossing borders, we make sure our goods don't cross borders either." Welcome to the weird world of trade sanctions.

Which almost never work, but which our politicians tout as the solution to nearly every trouble spot.

Jacob Weisberg, writing online for Slate.com, argues that, "In a world of trouble, it is partly an exercise in frustration. We often have no good options and need to feel that we're doing something."

But this "doing something" is no substitute for good policy. Meaning free trade, not sanctions.

Cuba might not be totalitarian today had we given up on sanctions and allowed trade and capitalism to enrich potential Castro opponents. As Weisberg points out, it's trade, not sanctions, that bolsters up a dictator's enemies.

Dictators have a strong survival instinct. Mere sanctions rarely work. For the real tough medicine, don't think sanctions, which are half measures to war. And don't think war.

Get tough on tyranny. Think trade.

This is Common Sense. I'm Paul Jacob.

Paul Jacob is member of the Board of Advisors for GRIH and is an acclaimed commentator who serves as the Senior Fellow for Americans for Limited Government. More of his columns can be found at http://www.getliberty.org/commonsense/index.php