For how long should we expect to live?

For how long should we expect to live? Though you may expect, due to some technology (cryonics, negligible senescence, etc.), to live an unusually long life by historical standards, you should act as if you will not. An admonition to “act as if X is false, despite a belief that X is true” may seem at first glance a call either for intellectual dishonesty or logical inconsistency, but it is neither.

This is because what we really mean by “act as if not X, despite X”, is that there should be no difference in your behavior depending on the truth or falsity of X. It is easy to see in general that, for any random proposition and any random decision, the truth or falsehood of the proposition may have no bearing on the decision. It is perfectly logical and consistent to say, “treat a black man as you would a white man,”; what we mean by it is: “whether a man is white or black should not impact how you treat him.” Conversely, one could say, “treat a white man as you would a black man”. The two are synonyms, at least literally. However, the connotations may be different: the first statement says, implicitly, “you already treat white men okay, but not black men,” whereas the second statement says the reverse.

So what I am saying is that the way you would act if you thought you would live a life of average length is probably better than the way you would act otherwise. That is, you may expect to live a historically unusual length of time, and as a result of that belief and a mistaken view of its implications, act dangerously (for yourself).

But what is dangerous, and why? The danger is, simply, that in anticipating a very long life, you may act in ways such that a violation of this expectation entails a wasted life. It is, in many respects, akin to anticipation of an afterlife, where one behaves, “on Earth,” as if Earth does not matter. If you are wrong, and there is no afterlife, then you will have accomplished nothing by acting only for its sake. Similarly, by acting as if you will live a very long time, you may make decisions which would cause your life to be of low accomplishment, should you in fact not live so long. On the other hand, if you act as if you will live a life of average length, then error here is easy to correct, simply because you will have plenty of time left should you turn out to be wrong (in this way, the situation differs from most afterlife myths, because your experience there is determined only by the way you lived your life on Earth, and there’s nothing you can do to change it once you’ve arrived).

Both hypotheses — long life and average life — must, for the time being, be treated as plausible, the schedule of technological advancement being difficult to predict, so one must consider the downside of betting everything on a merely preferred, as opposed to strongly preferred, hypothesis (I mean preferred in the sense of the perceived truth of the hypothesis, not how much you wish it to be true).

I have pulled a bit of a sleight of hand, in that I am now acknowledging, tacitly, that if you could really be sure (or at least very confident) of a very long life, then it would be perfectly appropriate to act accordingly, whereas before I had said that it makes no difference whatsoever. But with a slight rewording, my conclusion survives, because it is not, at present, reasonable to prefer the long life hypothesis over the other strongly enough such that it would, for these purposes, make a difference in this choice.

The structure of this argument bears some resemblance to that of Pascal’s Wager: choose one position because the downside in the case of error is much less severe. But my argument lacks the two fatal flaws of Pascal’s. First, I am arguing about action generally, not belief (which is a very special type of act). One can therefore follow my advice while maintaining intellectual integrity, whereas in taking the Wager one chooses to believe something for material benefit, the very definition of intellectual dishonesty. Second, I am not actually claiming infinite rewards or punishments (assumptions which Pascal had no basis for, and certainly no basis for assigning them exclusively to one side), merely very large ones; a life completely wasted is far worse than a life 1% wasted, even if in the second case you live 1,000 times as long. Don’t you agree?

So, plan on living 70 or 80 years, and organize your life such that if you die at 70, you will still have done worthwhile things.