‘Wilt thou not from this time cry unto me, My father, thou art the guide of my youth?’ Jeremiah was very fond of rhetorical questions, and there are going to be two here, one after the other in verse 4 and verse 5, which he doesn't intend to be answered. But he knows the answer; it is obvious, and he is just making a point.
In our age you could extend the meaning to include people being aware that it is a Creator who has made them, and brought them through, and given them some kind of conscience, and an awareness. But they have broken off from it, and ignored it, and trampled it down. It would seem few people are ready to ask this question. If we have not yet experienced the Lord’s judgment, is it because we do not deserve to experience it? Are we gambling on the fact that it will be withheld forever, or testing God to see how far we can push him?