[WS:] Not at all. I said they are socially constructed not dreamed up by individuals.
The main point of the nominalist position pertains to the relationship between ideas (universals to be more precise) and reality these ideas represent. It maintains that ideas are a product of human consciousness and do not exist in reality. It follows that they cannot cause anything in the realm of reality. In other words, altering depictions of reality (ideas) do not produce any changes in the reality itself. The realist position, by contrast, maintains that ideas have real existence - they are more real than empirical experiences of reality. http://en.wikipedia.org/wiki/Problem_of_universals
Of course, universals are not dreamed up, they are socially constructed as Emile Durkheim argued in _The Elementary Forms of the Religious_ which explicitly addresses the problem of the origins of categories inherited from Kant. Durkheim argues that categories through which people perceive and understand reality is shaped by their social relations, which in my opinion is among the most important ideas in the entire history of philosophy. In that sense, ideas exist independently of individual consciousness - they are are usually given as far as individual consciousness is concerned. In other words, they are intersubjective rather than subjective.
But the fact that they are intersubjective does not mean that that they are real in the same way as material objects are real. Contradictions exist only in the realm of ideas, not in reality. Reality is always in perfect harmony with itself. Thus, there were scientific arguments put forth not very long ago proving the impossibly of space flights. According to these arguments, there was a certain contradiction between the goals and the means to attain them: the energy obtained from fuel (means) was insufficient to bring the mass of that fuel into orbit (goal.) At a different time, a certain idealistic philosopher argued that motion is self-contradictory and thus impossible to exist (http://en.wikipedia.org/wiki/Zeno%27s_paradoxes).
It does not take much imagination to see that the arguments that "contradictions" in capitalism will bring it down or make it impossible to reform belong to the same genre of narratives.
Wojtek