idealist

The idealist is a restless fellow who sees evil in complacency; he regards the realist as a hypocrite at times because his realism is unrealistic. The realist, on the other hand, accuses the idealist of being impractical, because his insistence on destroying the value of the present way of life precludes positive action.
-- C. West Churchman, The Design of Inquiring Systems, Basic Books, Inc., 1971, pp 199

See idealism.