A regular reader of my blog commented to me, rather offhand, "To read your posts, you sound awfully sure of yourself. A little arrogant, even."
I'll leave the last part to wiser heads than mine to answer; I may well have an arrogant streak, and in fact I've remarked more than once that to have a blog at all implies a bit of arrogance -- you have to believe, on some level, that what you think and write will be interesting to enough people to make it worth doing. But I'd like to leave my own personality flaws aside for a moment, and take a look at the first part of the statement, which is saying something quite different, I think.
In saying that I sound "sure of myself," the fellow who made the comment was saying, so far as I can tell, that I sound like I've got all the answers; that my pronouncements on ghosts and faces on pub walls and Florida Skunk Apes, and -- on a more serious level -- ethics, politics, philosophy, and religion, are somehow final pronouncements of fact. I come across, apparently, as if I'm the last word on the subject, that I've said "fiat lux" in a booming voice, and now all is light.
Nothing could be further from the truth, both in fact and in my own estimation.
It's because I have so little certainty in my own senses and my brain's interpretation of them that I have a great deal of trust in science. I am actually uncertain about most everything, because I'm constantly aware about how easily tricked the human brain is. Here are five examples of just how counter-intuitive nature is -- how easily we'd be misled if it weren't for the tools of science. I'll present you with some explanations of commonly-observed events -- see if you can tell me which are true and which are false based upon your own observations.
1) Homing pigeons, which can find their way home from amazing distances, are navigating using visual cues such as the positions of the sun and stars.
2) Herding behavior in collies and other sheepdogs is learned very young; herding-breed puppies reared by non-herding breed mothers (e.g. a collie puppy raised by a black lab mother) never learn to herd.
3) A marksman shoots a gun horizontally over a level field, and simultaneously drops a bullet from the same height as the gun barrel. The dropped bullet will hit the ground before the shot bullet because it has far less distance to cover.
4) Flowering plants are temperature-sensitive, and spring-flowering plants like daffodils and tulips recognize the coming of spring (and therefore time to make flowers) when the earth warms up as the days lengthen.
5) Time passes at the same rate for everyone; time is the one universal constant. No matter where you are in the universe, no matter what you're doing, everyone's clock ticks at exactly the same rate.
Ready for the answers?
All of them are false.
1) Homing pigeons are remarkably insensitive to visual cues. An experiment, conducted at Cornell University, showed that pigeons' tiny little brains allow them to navigate by picking up the magnetic field of the earth -- i.e., they have internal magnetic compasses. This ability, called magnetotaxis, is shared with only a few other species, including at least one species of motile bacteria.
2) Herding behavior in collies is entirely genetic, not learned (although they refine the skill with training). Most amazingly, it is caused by a single gene. A dog with that gene can be trained to herd; a dog without it can't. Scientists are still trying to figure out how one gene can control a complex behavior like herding ability. This sheds some interesting light on the nature-vs.-nurture question, though, doesn't it?
3) In this classic thought experiment, the two bullets hit the ground at precisely the same moment. Vertical velocity and horizontal velocity are entirely independent of each other; the fact that the one bullet is moving very quickly in a horizontal direction, and the other isn't, is completely irrelevant.
4) Temperature has very little to do with the timing of flowering, although a prolonged period of cold can slow down early-flowering plants some. It used to be thought that flowering plants were timing their flowering cycles based on relative day length, and whether day length was increasing or decreasing; this clearly has something to do with it, but the mechanism controlling it is still poorly understood.
5) The General Theory of Relativity, which has been experimentally confirmed countless ways, actually says exactly the opposite of this. What it does say is that the speed of light is constant in all frames of reference, and this has, as one of its bizarre outcomes, that time is completely relative. Not only might your clock be ticking at a different rate than mine, depending on our relative motion, but events that look simultaneous to you might look sequential to me. No wonder Einstein won the Nobel, eh?
All of this is just to indicate that our intuition, our "common sense," and even our sensory information, can sometimes be very misleading. Science is our only way out of this mess; it has proven itself, time and again, to be the very best tool we have for not falling into error because of the natural mistakes made by our brains, the fallacy of wishful thinking and confirmation bias, and being suckered by charlatans and frauds.
A charge levied against science by some people is that it changes; the "truths" of one generation may be different from those of the next. (I call this the "They Used to Believe the Earth Was Flat" argument.) Myself, I find this a virtue, not a flaw. Science, by its nature, self-corrects. Isn't it better to put your trust in a world view that has the capacity to fix its own errors, rather than one which promises eternal truths, and therefore doesn't change regardless of the discovery of contrary evidence?
I realize that this line of reasoning approaches some very controversial thin ice for many people, and I've no intent to skate any nearer to the edge. My own views on the subject are undoubtedly abundantly clear. I firmly believe that everyone buys into the world view that makes the best sense of his/her world, and it would be arrogant for me to tell another person to change -- the most I can do is to present my own understanding, and hope that it will sell itself on its own merits. And for me, the scientific model may not be perfect, but given the other options, it's the best thing the market has to offer.