George Soros and Free Will

In a recent speech on the economic crisis George Soros makes some interesting comments about the cause of the financial crisis.
http://www.georgesoros.com/interviews-speeches/entry/remarks_at_the_festival_of_economics_trento_italy/

It's interesting to read his remarks in the light of the debate on free will, for example:
"Scientific method needs an independent criterion, by which the truth or validity of its theories can be judged. Natural phenomena constitute such a criterion; social phenomena do not. That is because natural phenomena consist of facts that unfold independently of any statements that relate to them. The facts then serve as objective evidence by which the validity of scientific theories can be judged. That has enabled natural science to produce amazing results. Social events, by contrast, have thinking participants who have a will of their own. They are not detached observers but engaged decision makers whose decisions greatly influence the course of events. Therefore the events do not constitute an independent criterion by which participants can decide whether their views are valid. In the absence of an independent criterion people have to base their decisions not on knowledge but on an inherently biased and to greater or lesser extent distorted interpretation of reality. Their lack of perfect knowledge or fallibility introduces an element of indeterminacy into the course of events that is absent when the events relate to the behavior of inanimate objects. The resulting uncertainty hinders the social sciences in producing laws similar to Newton’s physics."

Soros thereby gives us two reasons why he thinks determinism does not apply to the social sciences: incomplete knowledge and fallibility. When human beings make decisions they base these decisions on an incomplete picture and they sometimes make mistakes, they do not assess complex situations correctly.

I think most people will accept that both of these statements are true - and I think this is a good basis to argue for lack of determinism in human actions. Could it be that by "free will" what we actually mean is that we do not, and cannot, ever know all of the facts relevant to a situation and also that our human judgement is sometimes faulty?

If we did have perfect knowledge and never made mistakes then it seems much more plausible that free will might not exist, but can we accept that neither of these conditions is likely ever to persist?