# Possibly apocryphal worst estimate of probability?

My brain is telling me that three or four years ago there was a state legislator somewhere who, in the process of advocating for some position (probably abortion-related, but maybe not), brought up the possibility of men having babies with each other, rather than having a woman involved in the usual manner. He was asked about what the chances of that happening were, and he responded ‘50:50, because they either can or can’t’, or words to that effect. This strikes me as probably the worst calculation of odds that I can remember hearing about.

Does this ring any bells with anyone? Google isn’t helping me find this, so I’m beginning to believe that I imagined the whole situation.

50:50 is a prior probability estimate where you have absolutely no idea which alternative is more likely, or when you really believe they are equally likely. This is discussed a little bit as the “principle of indifference” and uninformative priors which cite how it is centuries old.

ETA there is an interesting discussion there of other probability distributions representing uncertainty such as the Haldane prior and Jeffreys prior.

The Daily Show had a bit a while back (go to 3:40) with some guy using exactly that logic regarding the Large Hadron Collider destroying the world. Just some lone nutcase, though.

John Oliver eventually asks (6:00) if they were the only two people left, they should try breeding–because it’s a 50/50 shot.

That guy’s knowe;dge of probability & estimates is very lacking, but this part was accurate. Males giving birth is fairly common nowadays; it happens about once a week. (Most of these are transgender males who have not had their female parts surgically removed.) Of course, almost any male can nurse a baby from their breasts, it only requires minor medical intervention (prescriptions for hormones).

I don’t know this particular scenario, but the whole “50/50” probability justified as “well, it’ll either happen or it won’t” despite the actual probability of one event being almost infinitely more likely than another is something I have come across many times.

There’s a reasonable chance that the guy is actually a genius.

Not that my contribution here helps (much), but this does seem to ring a bell in the archives of my mind, but I don’t remember any more than that – only that it seems more recent than 3 or 4 years ago. So I think that OP is probably not imagining the whole situation.

(It may be a 50/50 chance that he’s imagining it – either he is or he isn’t – but what is the probability that we are both imagining it? )

For the purpose of the probability estimate I’m pretty sure that such a person would not be considered “male”. So no, they weren’t accurate.

Clearly they were asking about “males” who have none of standard equipment required to bear children. Now the 50/50 reasoning is silly indeed but you can see where they get that twisted logic from seeing as there are only two possible futures one where it will happen and one where it won’t.

On that basis, I should start buying lottery tickets because, since I will either win or not win, it will be a 50/50 chance.

Best buy two tickets, to make sure.

Well if ticket A wins ticket B can’t and vice versa, the logic checks out!

Given sufficiently advanced medical technology, two men should be able to have a wider range of babies than two women, since two women would only have x chromosomes so could only have female children, while men have both* x* and* y* so could have both.

The chances of this happening are 50/50, or so they say.

That legislator’s statement is completely useless as a prediction. First, as of when is he predicting that there will be a 50/50 chance that two men will have a baby together? Was he saying that it will happen in the next year or the next ten years or the next one hundred years or the next thousand years or the next million years or the next billion years? A prediction that doesn’t give a limited time period for when it will happen is pointless. If someone predicts that the stock market will drop by 20%, the question is how soon this will happen. Is the prediction saying that this will happen in the next week or in the next hundred years? If someone says that the sun will go nova, are they saying that it will happen tomorrow or in the next trillion years? Furthermore, what did the legislator mean by two men? Does he only count cases where a baby has as genetic parents two individuals with XY chromosomes? Does he also count cases where the baby is born to someone with XX chromosomes who hasn’t undergone a full transition to male yet?

If you want to read a good book about what constitutes a useful prediction, read Superforecasting by Philip E. Tetlock and Dan Gardner. A useful prediction includes a precise time period during which the event is supposed to happen. It also includes a precise definition of what it would mean for it to come true. A prediction that allows the person doing the prediction to say “Well, it didn’t happen but it almost did, so that counts” is a useless prediction.

The weird claim regarding male-male breeding cited by the OP’s source is at odds with what I’ve been seeing in recent years. Namely, that it is the men who will die out (fairly soon) and women will be reproducing without them.

The earliest (serious?) cite I see regarding this is a book called Adam’s Curse: A Future Without Men from 2003. It says that shrinking y chromosomes mean human males only have about 5000 generations (or ~125,000) years before they go bye-bye.

Some variation of this has been touted regularly. Often with the number of years given as drastically less.

Of course the fact that hominid males, never mind mammalian males, have been around far longer than that, which suggests that dying out is not a likely occurrence, doesn’t seem to matter.

So this part of our fact-deprived culture now. With bad statistics thrown in.

Pretty sure this has already happened.

That’s exactly the type of usage I’ve heard this in.

The “it’s fifty fifty because it’ll happen or it won’t” thing is something that’s been said more than once, actually.

Of course, no one who says that ACTUALLY behaves that way.

Right, it’s like if you bought two quick picks and they both had the same number. What are the odds of that happening? Pretty close to the odds against you winning, and since that happens dozens of times a year we’ve got to assume that there are lots of people who buy multiple quick picks who get matching numbers. I’d feel like it was rigged.

Anyone who says that something could happen or it could not happen means that the probability of it happening is 50/50 doesn’t remotely understand probability. To say that something has X% chance of happening means that you’ve looked at all the circumstances surrounding what will happen and decide that the chance of it happening is X% and the chance of it not happening is 100 - X%. Another thing that the book Superforecasting makes a big point of is that you shouldn’t talk in ways like “This should happen” or “This might happen” or “This may happen” or “This could happen” or “This has a fair chance of happening” or “It’s not impossible that this will happen” or anything else that doesn’t assign a number to the probability. A forecast is useless if the forecaster doesn’t give a percentage for the probability. Don’t let a forecaster weasel out of their predictions by not precisely saying what event they are predicting or by not precisely giving a time period for the prediction or not giving a number for the prediction.

Choosing two tickets with the same numbers is actually a winning strategy, one of the few when playing the lottery.

If you win, against enormous odds, and someone else also - again, against enormous odds has the same numbers, you will get 2/3 of the prize, and they will get 1/3.