Struggling to stay on topic...

There is an additional distinction to make here. In most "soft" sciences, we are dealing with populations rather than individuals. The population rarely acts in a determined way to
dominate an experiment, whereas an individual will. Although it does happen. The best known example of this behavior is probably the
Long Term Capital Management collapse, where the market literally evolved new behaviors over time -- risks that were originally uncorrelated became correlated in response, and ultimately sank the company.
Soft science cannot treat individuals, because statistics don't apply even most of the time. Again, we are back to forensics and logical deduction. If that fails, then all we have is philosophy and speculation.
In dealing with individuals, whether or not forensics and logic are enough depends on the specific question. I'm still optimistic that most if not all questions of September 11
th lend themselves to this approach, and thus science is still the best answer.