what is unseen...

Frédéric Bastiat, a political economist in France during the 1800's, wrote an excellent (and somewhat lengthy) article titled What Is Seen and What Is Not Seen that describes well the multiple effects of enacted laws. Some of the topics discussed in this article are the effects, both seen and unseen, of the broken window fallacy, demobilization, taxes, theaters and fine arts subsidy, and public services. It's a great article if you find topics like this interesting. It was linked from this Mises Institute blog post.

I'll leave you with a quote:

Is there not something shameful in the role that the protectionist makes society play? He says to society: "You must give me work, and, what is more, lucrative work. I have foolishly chosen an industry that leaves me with a loss of ten per cent. If you slap a tax of twenty francs on my fellow citizens and excuse me from paying it, my loss will be converted into a profit. Now, profit is a right; you owe it to me."

The society that listens to this sophist, that will levy taxes on itself to satisfy him, that does not perceive that the loss wiped out in one industry is no less a loss because others are forced to shoulder it—this society, I say, deserves the burden placed upon it.

Thus, we see, from the many subjects I have dealt with, that not to know political economy is to allow oneself to be dazzled by the immediate effect of a phenomenon; to know political economy is to take into account the sum total of all effects, both immediate and future.