I recently had a discussion with a few friends on a particular issue and found that we were all in agreement; but as we discussed our reasoning, it became clear that they were objecting for practical reasons - I tried to turn the conversation toward the principles involved, and argued that a principled response was absolutely vital.
I proposed that even if a particular measure would accomplish a useful purpose in a practical sense, it ought to be opposed if wrong in principle. Unfortunately, at least one of my friends totally missed the point - and continued agreeing with me, but pointed to pragmatism instead of principle for support.
To me, a principled consideration of any issue asks the question, "Is this measure right or wrong?" while a pragmatic approach puts more weight on the question, "Is this measure effective or ineffective?"
Certainly, sometimes the two approaches will lead to the same position on a given issue, but I think faulty reasoning ought to be corrected even when it leads to a sound conclusion.
Can someone be principled and pragmatic? Most certainly - but I would argue that one ought to be principled first. I'm not suggesting a reckless disregard for consequences, but rather that one should consider the rightness/wrongness of an action before considering its results.
For instance, as discussed previously, the so-called Patriot Act purports to protect American citizens and National Security by allowing the government unconstitutional authority to warrantlessly wiretap. Pragmatically, this may in fact yield the hoped-for results of detecting and capturing terrorists, making it in this light tolerable, if not favorable; principally, however, it is an trespass into the territory of individual liberty and privacy, making it repugnant and potentially repressive. (It matters not that those in government supporting such measures have the most noble intentions to restrain themselves, or to apply it only for a temporary distress - it matters that the government boldly reserves this power to itself, to be used at its own apparently arbitrary discretion - and as it's been said: "There's nothing so permanent as a temporary government measure.")
As such, I feel the danger of this kind of pragmatic approach is that it seems to rest on the Machiavellian proposal that "the ends justify the means". But I reject such a notion. Unjust measures never advance a just cause - ironically and tragically, they utterly defeat it. You cannot simultaneously defend and trample liberty! Instead, I agree with the Scriptural assertion that you cannot (and ought not to try to) "do evil that good may come".
Again, once an action is carefully weighed and determined to be right, it's only prudent to consider the best way to go about it to minimize its negative impact. But making the right choice always has consequences, and that is why virtue cannot travel far without courage.