For years I have argued against economic boycotts against nations such as Cuba and China, arguing instead for business interaction and engagement. In China, for example, I think Pandora's box is open, and there's no reversing the effects of China's engagement with the US, no matter how much the Chinese government may think they can control the tide of modernity.
Jacob Weisberg has similar thoughts in Slate, and argues further that sanctions merely play into the hands of dictators:
America's sanctions policy is largely consistent, and in a certain sense,
admirable. By applying economic restraints, we label the most oppressive and
dangerous governments in the world pariahs. We wash our hands of evil, declining
to help despots finance their depredations, even at a cost to ourselves of some
economic growth. We wincingly accept the collateral damage that falls on
civilian populations in the nations we target. But as the above list of
countries suggests, sanctions have one serious drawback. They don't work. Though
there are some debatable exceptions, sanctions rarely play a significant role in
dislodging or constraining the behavior of despicable regimes.
Beyond the propaganda value Weisberg discusses, sanctions also create scarcity which is useful to the most brutal dictators, as they can use their powers of allocating resources to reward supporters and starve out opponents. My guess is that Saddam Hussein used his oil for food resources in this way.
I would be interested in a historical analysis of the effect of sanctions in the South African decision to end apartheid. Was this more due to sanctions or engagement, since a mix were employed.