Good intentions are not enough

From a commencement speech from Justice Scalia's, cited in Commentary's blog:

More important than your obligation to follow your conscience, or at least prior to it, is your obligation to form your conscience correctly. Nobody — remember this — neither Hitler, nor Lenin, nor any despot you could name, ever came forward with a proposal that read, “Now, let’s create a really oppressive and evil society.” Hitler said, “Let’s take the means necessary to restore our national pride and civic order.” And Lenin said, “Let’s take the means necessary to assure a fair distribution of the goods of the world.”

In short, it is your responsibility, men and women of the class of 2010, not just to be zealous in the pursuit of your ideals, but to be sure that your ideals are the right ones. That is perhaps the hardest part of being a good human being: Good intentions are not enough. Being a good person begins with being a wise person. Then, when you follow your conscience, will you be headed in the right direction.

A lot of evil can be done by good people pursuing bad causes. A lot of harm can be done by people with good intentions but who do not understand basic economics, which is why the notion of unintended consequences is central to the subject.