Pascal’s Alien Wager

We seem to be 3-1 here on the key issue of yelling to aliens, with Vakoch opposing the rest of us. So I’ll make this one comment here on this subject, and then turn my attention to topics where I disagree with Brin and Barkow.

In the ordinary Pascal’s wager, God is said to greatly reward those who believe in him and do what he favors. The rewards are so huge that even those who assign only a small chance to God existing are wise to try to make themselves believe. 

A standard response is to point out that a great many different Gods might exist, each of whom favor different actions. If you have little idea of which Gods exist or of what acts they favor, then there is little point in taking their rewards into account. You might as well just ignore them.

Douglas Vakoch seems to me to suggest an aliens version of Pascal’s Wager. He suggests that aliens might be near and already know we are here, but refuse to talk to us until we send the first message. But once we do talk first, they’ll send us lots of useful info. So even if we think the chances are slim that any aliens are around, the rewards would be so huge that we might as well take the chance.

The standard response mentioned above to the ordinary Pascal’s Wager also seems appropriate for this variation - there are many other possible kinds of aliens. For example, there may be aliens who will only shower us with valuable info if we show ourselves to be rational by keeping quiet for a long while before yelling. Or maybe there are aliens with a strong sense of status who will destroy us for being uppity by speaking louder than our status justifies. 

Surely it is not enough to simply point out the possibility of good outcomes from yelling. We must also consider the relative chances and values of good and bad outcomes. Regarding a choice to yell on purpose, there are two key relevant parameters: a value ratio, and a chance ratio. 

The value ratio divides the loss we would suffer if exterminated by aliens by the gain we would achieve if friendly aliens were to send us helpful info. I’d guess this ratio is at least one thousand. The probability ratio divides the chance that yelling induces an alien to send helpful info by the chance that yelling induces an alien to destroy us. I’d guess this ratio is less than one hundred. 

If we can neglect our cost or value regarding the yelling process, then we need only compare these ratios. If the value ratio is larger than the chance ratio, yelling is a bad idea. If the value ratio is smaller than the chance ratio, yelling is a good idea. Since I estimate the value ratio to be larger than the chance ratio, I estimate yelling to be a bad idea. If you disagree with me, I want to hear your best estimates for these ratios. 

To those who think aliens must already know we are here, consider a three-parameter family of possible aliens. Aliens could vary by distance, by listening intensity, and by listening luck. Aliens that are closer, listen intensely, and are lucky already know about us. But aliens that are distant, listen little, and are unlucky do not. 

While there are aliens in this parameter space who must already know we are here, or who will know when our signals reach them, there are also points in this space holding aliens who would not know of us if we did not yell. So it all comes down the the distribution of aliens over this parameter space. About which we are substantially uncertain. So I can’t see how one could plausibly be confident that no aliens would learn of us via our yelling. 

Also from this issue

Lead Essay

  • David Brin criticizes the possibly reckless turn in recent SETI research. He also speculates on what the great silence may say about human societies. It may not be such a good idea to go about shouting to the cosmos - not when we have so little idea of what may be out there.

    That said, Brin speculates on the nature of any intelligent life we are likely to meet. He notes that our scientific and technological society is very unusual when compared to societies of the past: It is, he says, diamond-shaped, with relatively few at either the bottom or the top, and with a broad equality of social station, rights, and even wealth in the middle. Maintaining such a society is hard work, and one reason we seem to be alone in the universe may simply be that very few alien civilizations have escaped from feudalism or something like it.

Response Essays

  • Robin Hanson runs a cost-benefit analysis on our use of very loud radar signals. He finds that if there is even a small probability of a hostile civilization hearing us, then the risks are not worth the rewards. This conclusion holds up under fairly severe assumptions, and it grows much firmer as we consider our likely technological developments in the near future. Astronomy, moreover, is advancing rapidly, and it will likely tell us much more about the probability of existence and the nature of extraterrestrial life. When it does, we may have a better idea of the wisdom of sending out very loud radio signals. In the meantime, he concludes that yes, humanity should indeed shut the hell up.

  • We have few tools at our disposal to learn about intelligent extraterrestrials - if they even exist. But one relatively powerful tool is evolutionary psychology. Jerome H. Barkow reviews some findings from terrestrial evolutionary psychology and considers their implications for alien life. We will learn a lot if we can discover what aliens find sexy, he claims - because sexual selection has overwhelmingly influenced terrestrial animals, including ourselves.

    We will also learn a great deal by observing aliens’ predation history, their group cooperation, and their genetic transmission of culturally favored traits. Of course, these observations will have to wait for first contact. Barkow concludes by agreeing with Robin Hanson - until we know more, humanity should probably keep relatively quiet.

  • Douglas Vakoch argues that active SETI is not to be feared: If highly advanced civilizations exist out there, they will have highly advanced radio detection equipment. If they are anywhere near us, then they will have known about us for decades. Messaging them can do no more harm than what we have already done, and it may do us a great deal of good, particularly if these civilizations are waiting for us to make the first move, and if messaging them directly is the signal they need to initiate contact.