Which is exactly my point.

You: "But that doesn't answer the question. WHY does the air get pushed down?" They: "Because of such-and-such effect..." You: "But that doesn't answer the question. WHY does such-and-such effect happen?" They: "Because of fluid viscosity and boundary layers and navier-stokes blah blah blah..." You: "But that doesn't answer the question. WHY does fluid have viscosity?" They: "Because a such-and-such bonds between the molecules of the fluid..." You: "But WHY..."

See how it goes? Turtles all the way down.