Got an email query about martial arts, connected to the recent posts. Question was, How do you know for sure the things you have been studying will work if you need them?
And the answer is, of course, you don't know for sure.
Few things in life are an absolute lock. You can probably bet the farm that the sun will come up in the east tomorrow and not the west, if you could find somebody stupid enough to take that action. I am willing to allow that fresh water will freeze at zero Centigrade, and that Darwin's Theory of Evolution is closer to fact than not -- but unless you have a working crystal ball and have made your deal with the Devil, predicting the future accurately in the face of ordinary chaos is a hard row to hoe. Weather guys with billions in computer sensory gear and satellites and Doppler get tomorrow's forecast wrong half the time, and predicting it reliably two weeks out in most of the world's active weather regions? Yeah. Right.
Still, there are educated guesses, based on a bunch of things -- direct experience and observation; well-documented versions of those by others, stuff like that. And the more you play in an arena, the more likely it is that you will gather data that is useful.
Here's an easy example: You don't need to know much about gymnastics at all to see if the guy doing the double-full off the high bar sticks the landing. If he falls down, it's obvious.
To decide whether a tiny bobble on an inverted giant swing and high release is worth a tenth or a tenth-and-a-half might require some skill and practice as an observer. But even if you've only watched the sport on TV or seen a couple meets in person, you can quickly tell whether or not a routine nailed it dead on or somebody stepped out or lost her balance. You learn by listening to the ex-gymnast doing the color commentary pointing it out and associating that with what you see.
You don't have to be able to do the move to see it falter, any more than you have to be a world-class guitarist to hear a bad note if the player hits one. Being an educated watcher is enough to give you a certain amount of useful information.
My experience in martial arts is shallow, save for one, but it is wide. Having studied a bunch of things over forty-odd years, and having seen a lot of different players, some of them world-class, move, I've had some education in certain ways of motion. I can't do some of their moves, but I know good when I see it. I can compare and contrast, weigh this against that, and come up with a working observation or two.
Thus in my personal experience, both as a watcher and a doer, the art I'm in now offers principles that seem more effective and useful than the other arts in which I have been involved. And while it is true that I haven't walked the mean streets to kick ass and take names to sharpen my skills, I have used some of the arts that I view as less effective to make do. If I believe that silat, based on my own experience, is more useful for me, then the notion that it will work as well or better than the other arts I studied is not such a reach.
As Randy Newman said in the theme song for Monk: I could be wrong now ... but I don't think so!
This doesn't say anything about other folks who bring different experiences to the table. They know what they know. But without getting all existential about it -- who can know anything? -- I don't lay awake nights worrying that what skills I have.