The Problem with Pragmatism
Recycling a comment I made on this post by Bobvis:
The problem with pragmatism is that it's just not practical. Ideal pragmatism is great--freed from ideological constraints, you can just do what works!--but ideal pragmatism isn't an option.
What we actually get is real-world pragmatism: People's beliefs about what policies produce the best results are driven more by ideology and cognitive bias than by actual evidence. And those are just the people who at least make a good-faith (if weak) attempt at intellectual honesty. Those with vested interests in certain policies may deliberately present evidence skewed in favor of their side. In short, we get something not entirely dissimilar to the system we have now.
The weakness of a principled approach--that it leaves no room for discretion--is also its strength, since discretion is as likely to be used for ill as for good. More likely, I'd say. An electorate with a knee-jerk anti-government reflex is likely to produce better policy than one laboring under the illusion that it's enlightened and pragmatic.
The best approach, I think, is to give liberty the benefit of the doubt in all cases, much as we do for criminal defendants. Only intervene where there's a strong consensus that it's absolutely necessary. For example, if I were writing a constitution, I would require a 4/5 majority in the legislature to pass a new law, and require only a simple majority, or perhaps a 2/5 minority, to void an existing law.