I agree: there is no "forever guarantee," especially as our life spans increase to experience new problems and our ability to detect problems improves, we discover new things that may be killing us or may have been harming us in the past.
That said: I'm unclear on the double standard you were pointing out. Was it something that I said indirectly? If that is the case, the point of my statement is that we have a longer body of evidence for traditional food engineering (selection, cross-breeding, etc) than we do for direct genetic modification by several orders of magnitude--conservatively: 50 years compared to ~5,000 years. That is A) not to say we haven't borked up a few times with traditional engineering and B) not to say that GMO are definitively less safe because they are new. It is just to say that we have definitively less evidence on the matter, and 10-20 years--less than half of a lifetime--is not a resounding endorsement.
All that said: I don't think this is even a particularly significant piece of evidence in the discussion--compared to say: reliable testing standards, risk analysis based upon the changes being introduced rather than the method of introduction, etc--as long as we can agree that 20 years of evident safety does not in itself prove that anything is certainly safe.
My comment was aimed more at one side in the GMO debate rather than specifically at you.
we have a longer body of evidence for traditional food engineering (selection, cross-breeding, etc) than we do for direct genetic modification by several orders of magnitude--conservatively: 50 years compared to ~5,000 years.
This is not true. First, both "traditional food engineering" and GMO are ridiculously broad terms and it's hard to say anything meaningful which applies to the whole category. The main issue, however, is that traditional cross-breeding...
Basically: How does one pursue the truth when direct engagement with evidence is infeasible?
I came to this question while discussing GMO labeling. In this case I am obviously not in a position to experiment for myself, but furthermore: I do not have the time to build up the bank of background understanding to engage vigorously with the study results themselves. I can look at them with a decent secondary education's understanding of experimental method, genetics, and biology, but that is the extent of it.
In this situation I usually find myself reduced to weighing the proclamations of authorities: