It turns out that you only need 23 people for it to be more likely to find a shared birthday than not. - David Franklin

I guess… it was just a shocking event. We’re not used to someone like him being President.” Here, the student reveals an availability bias in which we expect future outcomes to look like what has gone before.

With 80 people, the size of this classroom, the probability that there will be no shared birthdays is so tiny as to be virtually impossible.

The phrases ‘certainty is an illusion’ and ‘think probabilistically about the world’, both introduced in the first class, are the first two examples of high-level concepts which Dan calls airport ideas.