Monthly Archive for February, 2016

Political Strategy

It now seems likely that:

  • In order for either Ted Cruz or Marco Rubio to become the Republican nominee, he must first consolidate the anti-Trump vote, which is to say that either can succeed only if the other drops out.
  • Cruz and Rubio have approximately equal chances of driving each other out.
  • Each would prefer to drive the other out sooner rather than later — i.e. before Trump wraps this whole thing up anyway.

Given that, it seems like one of the following two things should happen at tonight’s debate:


  1. Cruz, after making an eloquent case against Trump and explaining why he thinks it’s important to keep Trump out of the White House, turns to Rubio and offers to flip a coin right on the spot. The loser drops out of the race and the winner takes on Trump.
  2. or

  3. Rubio, after making an elegant case against Trump and explaining why he thinks it’s important to keep Trump out of the White House, turns to Cruz and offers to flip a coin right on the spot. The loser drops out of the race and the winner takes on Trump.

This gives each of them only a 50% chance of survival. But if they’ve already each got only a 50% chance of survival, that’s no loss. And it substantially increases the value of survival, because it gets things over with now instead of a month from now.

If I’m wrong in saying that each currently has a 50% chance — if instead, say, Cruz has a 60% chance and Rubio a 40% chance or vice versa — then they can flip an appropriately weighted coin.

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Antonin Scalia

scaliapicMy favorite Scalia story is from Ted Cruz’s book A Time for Truth. This took place in 1986, when the departure of Warren Burger had created a vacancy on the Supreme Court, and it was clear that attorney general Ed Meese would be President Reagan’s most influential advisor on choosing a nominee. According to Cruz:

Everyone knew that two of the stars on the conservative side, and thus possible nominees, were Robert Bork and Scalia, both on the D.C. Circuit. So one day Scalia was walking in a parking garage at the appellate court when two U.S. marshals stopped him. “Sorry, sir,” one of them said. “We’re holding this elevator for the attorney general of the United States.”

Scalia pushed past them, entered the elevator, and pressed a button. As the doors closed, Scalia shouted out, “You tell Ed Meese that Bob Bork doesn’t wait for anyone!”

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How to Be Reasonable

Listening to Season One of NPR’s podcast Serial, which is the story of a real-life murder case, I came away about 80% sure that the defendant was guilty and 100% sure that I’d vote to convict him. This got me to pondering whether my standards for reasonable doubt (apparently less than 80% in this case) are in fact reasonable.

So I wrote down the simplest model I could think of — a model too simple to give useful numerical cutoffs, but still a starting point — and I learned something surprising. Namely (at least in this very simple model), the harsher the prospective punishment, the laxer you should be about reasonable doubt. Or to say this another way: When the penalty is a year in jail, you should vote to convict only when the evidence is very strong. When the penalty is 50 years, you should vote to convict even when it’s pretty weak.

(The standard here for what you “should” do is this: When you lower your standards, you increase the chance that Mr. or Ms. Average will be convicted of a crime, and lower the chance that the same Mr. or Ms. Average will become a crime victim. The right standard is the one that balances those risks in the way that Mr. or Ms. Average finds the least distasteful.)

Here (I think) is what’s going on: A weak penalty has very little deterrent effect — so little that it’s not worth convicting an innocent person over. But a strong penalty can have such a large deterrent effect that it’s worth tolerating a lot of false convictions to get a few true ones.

In case I’ve made any mistakes (and it wouldn’t be the first time), you can check this for yourself. (Trigger warning: This might get slightly geeky.) I assumed each crime has a fixed cost C to the victim and a random benefit B to the perpetrator. For concreteness, we can take C=2 and take Log(B) to be a standard normal distribution, though the results are pretty robust to these particulars. (Or, much more simply and probably more sensibly, take B to be uniformly distributed from 0 to C — the qualitative results are unchanged by this.)

Continue reading ‘How to Be Reasonable’