OK, this is serious displacement activity, but I can't stop myself...
Further to the two posts yesterday (main explanation, and follow-up), this is what I believe is wrong about Tet Woo Lee's argument in his letter in the New Scientist on 3 July.
Lee says: "What you are changing is the group of parents we are talking about."
Correct, but his argument is based the group of parents changing from all those with at least one son to all those with at least one son born on a Tuesday, which is not right. We are not changing it to all those with at least one son born on a Tuesday, we are changing to all those who declare the son that was born on a Tuesday. The group of parents we are talking about now does not include those with two sons but who choose to declare the one that born on some other day.
[Update 6 September 2010. See http://news.bbc.co.uk/1/hi/programmes/more_or_less/8735812.stm for a rather better explanation of all of this.]