Like Jane Galt, I don’t have an opinion on gay marriage and – also like Jane – I find many of the arguments, both for and against, unconvincing.

But Jane makes a good argument for the stability of institutions – with analogies to income tax, divorce and welfare – and the unintended consequences of what can happen when you change them.

Let me take three major legal innovations, one of them general, two specific to marriage.

The first, the general one, is well known to most hard-core libertarians, but let me reprise it anyway. When the income tax was initially being debated, there was a suggestion to put in a mandatory cap; I believe the level was 10 percent.

Don’t be ridiculous, the Senator’s colleagues told him. Americans would never allow an income tax rate as high as ten percent. They would revolt! It is an outrage to even suggest it!

Many actually fought the cap on the grounds that it would encourage taxes to grow too high, towards the cap. The American people, they asserted, could be well counted on to keep income taxes in the range of a few percentage points.

Oops.

It would be easy to misread Jane’s post as an argument against gay marriage but I don’t think she meant it to be read that way.