I particularly liked:
the benefits of civilization rest on the use of more knowledge than can be used in any deliberately concerted effort...
...which is the very foundation of the Austrian school of economics' argument against centrally-planned economies - and, by extension, political and social systems. I might point out, however, that it is the very expediency which, according to Hayek, is objectionable on the policy level due to the resulting systemic constraints on human action, is, at the much more microeconomic level of individual economic decisions incorporating knowledge on the level Hayek rightly claims to be unattainable to central planners, the very engine driving a free-market economy. If I understand him correctly, it isn't expediency per se, then, that is the problem, it is the level at which it is applied.
I think that's so, since the government has the power to force its plans and schemes onto individual people.
OTOH, the principle of adhering to principles applies to the way an individual runs his life as well. For instance, it may be momentarily expedient to lie, but that would contradict the principle that one should never fake reality.
But in the case of an individual, he usually only damages himself by choosing expediency over principles.