We don’t need to know everything, we just need to know enough to make a decision off of. We see the same medication work 10000 times, we have evidence that we should use it. We see that a metal expand the same way when we test it 100 times. We can use that metal when we need something that expands consistently with tempreture. We don’t need to know everything because our lives doesn’t involve everything, and if we do discover something new, we either test it ourselves, or submit it to other groups to test.