This is actually something that could be drawn out as a lesson in the history of science and idea. Between your comment and my comment, we’ve quickly identified a number of points at which one could say we “understood” or could “explain” tides. Going from something like “It’s the Sea Gods Rolling Around in the Great Bathtub” to “The moon causes them” would be a major advancement, yet as you point out, not an understanding. Of course, the fact that we now have a gravitational model that incorporates both the sun and the moon (and understand the importance of tidal forces in planetary dynamics elsewhere) is great, but perhaps people in the future will look back through the lens of Wikipedia and note that we had not yet identified the graviton, so we didn’t fully get it.

The most salient features of the tides are probably:

Periodicity at the first order (up and down almost twice a day); Spring/neap tides (longer term periodicity) and different amplitudes in different areas of the coast and other details of what happens with the tides near shore. (Compare the tides in Miami, FL with the tides in Eastport ME for a dramatic example.)

Knowing the influence of both the moon and the sun, understanding the math and physics of the harmonics, and also how physical geography affects water moving around in ocean basins are all needed to BOTH predict the tides as they are and understand them well enough to explain and in turn (in theory) predict what tides would look like anywhere they might exist.

The average person is probably willing to understand that “the moon did it” but that is perhaps closer to “the sea gods are rolling around” than to the fully scientific modern explanation. But, if the average person simply wants to know why the tides vary across the month and why they are different in different places, and what’s all this about tidal forces on the small moons circling giant planets, then a certain amount of science/math literacy is probably needed.

It is a little like having to know something about spectra and spectroscopy to really enjoy so many things in the cosmos.

An note to Sheila. If I were that far off in time-frame then your note would hardly count as a “small correction”. Consider that tides are caused by both the gravity of the Sun and the Moon. So we could not have understood the tides until we understood gravity itself, And that did not take place until Issac Newton advanced the universal law of gravitation in 1687, in his seminal treatise “Principia”. Yet even the great Newton, in his attempt to understand the tides, got it wrong.

What complicates matters is that it’s not the gravity of the Sun and the Moon but the **difference** in gravity across Earth’s physical body that causes the tides. Not only that, the tides on Earth, in spite of how they are drawn in textbooks, do not line up with the Moon and Sun, but sit ahead of them on Earth’s surface. Small advances in detail were made over the years since Newton, but not until G.H. Darwin’s (second son of Charles Darwin) work “The Tides and Kindred Phenomena in the Solar System” (1901) did a complete solution of what causes the tides get solved.

So when I said a “couple hundred years” i could have justifiably said only “a century,”, but I was planting the time frame halfway between George H. Darwin and Isaac Newton, out of respect for those who came in between.

Note that for someone to assert “the Moon causes the tides” (as all observant ancient civilizations knew) but not be able to explain why, does not constitute an actual understanding of the phenomenon.

Again, thanks for your interest in my comments.

-NDTyson

I’m still not convinced O’reilly was arguing from ignorance when he said that. It always sounded to me like he was using the tides and the sunrise as a metaphor for the miracle of the world not spontaneously ending while he sleeps. It’s still a crappy argument, particularly given the inherent ethnocentrism. But I’ve never been particularly impressed by how the skeptic community handled this.

How would you have handled it? Impress me.

This is part of why atheists are accused of being arrogant. The theist thinks that no one could be an atheist without having all the gaps filled. The gaps are obviously not all filled, therefore the atheist holds to arrogant delusions that they are filled. It does not occur to the theist that atheists are simply comfortable with unfilled gaps.