The obvious answer is many things now taken as truth were once considered heretical; and also many completely wrong ideas (ether, the humors, etc) still produce

The obvious answer is many things now taken as truth were once considered heretical; and also many completely wrong ideas (ether, the humors, etc) still produced useful science and technology. By all means demand falsifiability of any claims to truth, but don't insist that any one of us or all of us collectively are worthy arbiters of truth.