Your question implies that they can't. The philosophy that things are advancing (or if they are not,
they should be) is questionable. The First Noble Truth of Buddhism that all life is suffering, or the
teaching of Christianity about Original Sin, suggest that the idea of advance is either an illusion
(Buddhism) or a natural impossibility (Christianity). The idea of advance became dominant in the
Nineteenth Century when the Western world began to get very rich. Today advance it is a popular
concept in the media. If inflation is down and the economy is strong we imagine we are advancing.
But the implication of your question is probably right, we are not really advancing in any moral sense.
The great Nineteenth Century historian Ranke said, "Every generation is equidistant from eternity."
Your question seems to imply as much.