Even if I don't believe in aliens, I think I can appreciate a crop circle as much as any UFOlogist. The shapes that appear in fields, primarily in the UK, are sometimes astonishing, and moreso every year, as those that create them gain experience and skill. It seems obvious to me (and don't most opinions just seem so obvious?) that they're created not by interstellar travelers, but enterprising human beings.
That statement is that, obviously, humans could not make crop circles. That, yeah maybe people could make some of the smaller, simpler ones, but that the very large, very elaborate crop circles are outside of the range of human ability.
Really? Really-really? Are you sure that's an argument you want to make? You're talking about the cleverest animal on this ball. You're talking about the animal that achieves the impossible so often that it's starting to get boring. We don't drop our jaws in wonder when a four-hundred fifty ton 747 is able to support itself on thin air, it's only of passing interest when the guy on the corner is juggling torches, and most of us don't care when a figure-skater pulls off a triple-axel, which none of us could ever hope to do. But the moment it looks like something might be communicating with us from another planet (in a hopelessly obscure way, I might add) it's way outside of the realm of reason that a group of friends could flatten crops in a fancy shape.
Say what you want, about what you want, and I'll try to listen with an open mind. When you start to put limits on human ingenuity, you will lose ground with me very quickly.