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:
- I review aggregations of authority from one side and then the other--because finding a truly unbiased source for contentious issues is always a challenge, and usually says more about the biases of whoever is anointing the source "unbiased."
- Once I have reviewed the authorities, I do at least some due diligence on each authority so that I can modulate my confidence if a particular authority is often considered partisan on an issue. This too can present a bias spiral checking for bias in the source pillorying the authority as partisan ad infinitum.
- Once I have some known degree of confidence in the authorities of both sides, I can form some level of confidence in a statement like: "I am ~x% confident that the scientific consensus is on Y's side" or "I am ~Z% confident that there is not scientific consensus on Y"
I would agree with you that the quoted statement is not terribly persuasive. I was simply encapsulating the actual argument at hand, instead of the straw-man argument of "method versus outcome." And while the vagueness diminishes the magnitude of the evidence, I don't believe it makes it non-zero.
To your second point:
I would add to ChristianKI's apt reply that while conventional modifications via breeding can eventually have monumental effects, direct genetic modification can rapidly--over the course of a single generation--have monumental effects that may have unintended side effects attached to them due to a lack of understanding of the intricacies of genetic interactions.
I can't find any sense in ChristianKl's answer, but maybe that's just me.
My basic problem with your position is that "conventional modifications via breeding" are better described as picking from a set of random mutations those where the phenotype looks appealing. I don't know why you think it's a safe method, especially compared with making targeted genetic changes directly.