An interesting Facebook post by the noble Vipul Naik, reprinted with his permission.  Vipul:

I think Bryan Caplan could have won the Intelligence Squared debate by pandering to his audience in the following ways:

(1) Stated that “America is a nation of immigrants.”

(2) Talked about the Founding Fathers and the Constitution.

(3) Stated that immigration restrictions are racist.

(4) Waxed eloquent about Ellis Island.

(5) Talked about how awesome immigration is and what nice people immigrants are.

(6) Made the claim that open borders is no big deal, because, economic
determinism suggests that migration flows aren’t really affected by
migration restrictions

(7) Made the claim that open borders is no big deal. All it means is a
little more migration from Mexico and Canada to the US, and that the
people who already migrate have proper documentation, and quoted Alvaro
Vargas Llosa as the authority on the subject.

(8) Endorsed minimum wage proposals as a complementary policy to
creating a strong, ethnically diverse, and anti-racist American middle

(9) Pooh-poohed Unz’s claims about a billion people as pie-in-the-sky racist scaremongering.

(10) Claimed that if America doesn’t make migration easier, all the
software programmers and gardeners and farmers will migrate to Canada or
the UK instead. And we know how awful that would be for America.

Vipul adds:

re: pandering, I think that points (1)-(4) are to quite an extent true,
but non-central to the case for open borders. (5) is too vague to be
true or false. I believe (6)-(10) are mostly false, but one could make
reasonable arguments in favor of them in some circumstances. But to the
extent they’re true, they either oppose or are non-central to the case
for open borders.