Suppose one fine day you pick up your Smith & Wesson 586 ($809 MSRP), a .357 Magnum revolver—which means that thingee in the middle spins around, advancing one round at the time. It has an old-fashioned, manly wooden grip and six inch barrel (not wooden).
You savor it for a moment, considering it is not, or at least not yet, on a list the White House can peruse. Then, as you take out your cleaning rag, a knock comes at the door! The rag and oil can are pushed aside. As you load it, you shout, “Just a minute!”
The hallway seems longer than usual. But as you near the door—the gun comfortably nestled inside your pocket—you begin to relax as you recognize the outline of the man standing at the entrance. It’s your neighbor Fred, a professor down at the college who frequently drops by to try his latest theories out on you.
Fred had been reading Peter Kreeft’s Summa Philosophica and came across this passage:
[S]ometimes we need certainty, e.g. in matters of life or death. If a gun had 100 chambers, then 100 of them must be checked, yielding certain safety, and not just 99, unless you want to play “Russian roulette.”
Fred notices the bulge in your pocket and says, “What a coincidence! Would you, for one million tax free dollars, play Russian roulette with your .357? One chamber with a round, the others a empty, and so forth?”
Since you are not an idiot, you say no. This is because you deduce there is a 1 in 6 chance you’d fail to take the dog for his evening walk, this night or any other.
It is not certain you’d live, nor is it certain you’d die. If it were certain you’d live, every chamber would have to be empty; and for it to be certain you’d die, every chamber would have to be loaded. So much is elementary.
But Fred makes the game more interesting. “Suppose I were to build a machine which is like your gun but could hold N chambers. Only one would be loaded, the rest empty. Same game. How large would N have to be for you to play?”
And that, dear reader, is the question to you. Is an N of 1,000 large enough? That gives you a probability of 999/1,000 of not ceasing upon the morrow. But it’s still a 1 in a 1,000 shot of the wrong kind of haircut. Maybe 10,000?
Besides telling us your N, would you agree with me that no matter how large N gets it is never certain you will survive? And that the phrase practically certain has the same logical relation to certain as practically a virgin has to a virgin?
Do you think you would say N = NA, or N = NaN. I.e., no number? That you would refuse to play? Then I wonder why you strap yourself into your car and drive yourself to your paycheck-issuing location each weekday. There is, after all, a non-zero chance that you will become the subject of a high school drivers training film.
Real examples abound. Flying, skiing, walking along a road, eating donuts, listening to NPR, etc. All which prove you are willing to endanger your life in return for moola or thrills.
Is there a difference between purposely risking your life, as in Russian roulette, and routinely risking it, as in driving to work? If so, what is it?