The argument that you have to go with what you know? Sounds strange because what else do you have. Then you would also probably want to apply the cautionary principle, at least for changes that would have a great impact.
Yeah, see there's the problem. Let's take, for example, global warming and let's assume that AGW isn't established. (The argument works the same for other things such as GMO and climate engineering, but I'll use AGW.)
Does the cautionary principle work this way: "We're not sure humans are responsible for global warming. But trying to restrict our CO2 output will definitely harm our economy and likely cause a reduction in our ability to produce food. It will raise the cost of energy, causing some people to freeze to death. The cautionary principle says we shouldn't restrict CO2 output."
Or does it work this way: "We're not sure humans are responsible for global warming. But they might be. The cautionary principle says we had better reduce our CO2 output so that we don't risk causing massive damage to our planet."
What happens is that people always raise these arguments to support the conclusions they've accepted for other reasons. Nobody is actually swayed by them. They're basically window dressing. These are issues where both sides claim great impact and claim that the cautionary principle and the lack of complete knowledge justifies the conclusion they wanted in the first place for completely different, and unrelated reasons.
You have to address the real reasons people reach the conclusions they reach. If the evidence is not strong enough to compel either conclusion, people will generally argue for the conclusion that benefits them. And then it's not a scientific argument, it's over who wins and who loses.