Charles Moore's hapless attempt on the Today programme to oppose gay marriage has been widely decried. But I suspect that, underneath his waffle, there is a useful perspective which is in danger of being forgotten.

Charles was trying to express the classical conservative disposition. This - associated with Burke, Oakeshott and partially Hayek - is sceptical about the powers of individual reason. Instead, it believes that traditions embody more wisdom than we know, and that deviating from these traditions can lead to unforeseeable effects. As Oakeshott said (pdf):

The total change is always more extensive than the change designed; and the whole of what is entailed can neither be foreseen nor circumscribed.

In this context, Moore's incoherence was not an individual failing, but a necessary consequence of his ideological position. If you believe that individual rationality is a weak tool and that consequences cannot be fully foreseen, then you cannot articulate your position well because - ex hypothesi - you cannot know the costs and benefits of social change.

When Norm says there are no reasoned arguments against gay marriage, he's right. But to conservatives like Moore, this tells us about the limits of reason, not the merits of gay marriage.

Herein, I think, lies a difference between what Hopi calls social conservatives and metropolitan liberals. Social conservatives such as Moore are sceptical about rationality and cleave to tradition; liberals are more rationalist.

Personally, I have sympathy for this conservative disposition. The cognitive biases programme has taught us that rationality is indeed a weak tool, and society is too complex to be fully understood by any single mind.

However, I have less sympathy for its application in this this case, for two reasons.

1. The case for legalizing single-sex marriage is an intrinsic one; the move embodies important values of equality and freedom. If you want to claim that there are costs of such a move sufficiently large to offset these intrinsic values, you should at least give us some clue as to what they might be.

2. Many of the conservatives who are so opposed to gay marriage have been quite relaxed about other big social changes of recent decades such as the collapse of trades unions, globalization and the growing power and wealth of top managers. (And others might add that they are keen to discard the traditions surrounding the welfare state and NHS). That the conservative disposition should have deserted them on these issues makes me fear that they are not coherent thinkers but merely bigots who hate people who are not like themselves, such as gays and workers.

But here's my worry.The conservative disposition is a valuable intellectual tradition. It would be a great shame if it were discredited by its association with anti-gay bigotry.