The public debate about same-sex marriage has raised some really interesting questions about the nature and rationale of marriage. Marriage is an institution which we observe across space and time, but why do we have marriage and why has it been so prevalent across societies? Marriage in the West has been eroded over the past number of decades and many see the extension of the marriage franchise to same-sex couples as a further weakening of the institution. Unfortunately, much of the debate on this issue is being stifled and sometimes there is more heat than light. However, I recently came across a really good debate on Piers Morgan's CNN show, which featured Ryan Anderson of the Heritage Foundation, a conservative think tank based in the United States.