From The Next 200 Years, by Herman Kahn

It is often suggested that adequate technology assessment (TA) studies should be required for any technical innovation before proceeding with commercial applications--that the burden of proof be placed on the people who want the innovation. It sounds reasonable to say that it is up to the innovator to prove that his innovation is safe, but there are some difficulties in this position.

If as a general matter high standards of justification were set and enforced, many important projects would not get off the ground. Full and definitive TA studies of complex projects and phenomena are often simply not feasible.

We have never seen an a priori analysis that would justify the conclusion: "Let's go ahead with the project; we understand the innovation and all of its first-, second-, and third-order effects quite well. There can be no excessive danger or dfficulties."

Indeed, many times the people looking for second-, third-, and even fourth-order effects have often seriously erred about the first; in any case, they usually cannot establish the others with any certainty...

None of the above is meant as an argument against doing TA studies.On the contrary, in many cases much will be learned from such studies. But one cannot expect them to be complete and reliable, and placing too great a requirement on innovators doing such studies can simply be an expensive way of doing less; it entails all the problems and disutilities of excessive caution and of slowing down innovation in a poorly designed--and often capricious--manner.

Which is all too often the real point.