There is a difference between responsible criticism that aims for success and defeatism that refuses to acknowledge anything but failure. Hindsight alone is not wisdom, and second-guessing is not a strategy.
The sceptic will say, 'It may well be true that this system of equations is reasonable from a logical standpoint, but this does not prove that it corresponds to nature.' You are right, dear sceptic. Experience alone can decide on truth.
It is the will of God that we must have critics, and missionaries, and Congressmen, and humorists, and we must bear the burden. Meantime, I seem to have been drifting into criticism myself. But that is nothing. At the worst, criticism is nothing more than a crime, and I am not unused to that.
I wouldn't be worth my salt if I weren't attracting some controversy and criticism. Everyone in the world who has done something in life has attracted criticism.