One of the key concepts in Common Law is that of the reasonable man. Re-reading A.P. Herbert, it struck me how his famously insulting description of the reasonable man bears a deep resemblance to that of the ideal rationalist:

It is impossible to travel anywhere or to travel for long in that confusing forest of learned judgments which constitutes the Common Law of England without encountering the Reasonable Man. He is at every turn, an ever-present help in time of trouble, and his apparitions mark the road to equity and right. There has never been a problem, however difficult, which His Majesty's judges have not in the end been able to resolve by asking themselves the simple question, 'Was this or was it not the conduct of a reasonable man?' and leaving that question to be answered by the jury.

This noble creature stands in singular contrast to his kinsman the Economic Man, whose every action is prompted by the single spur of selfish advantage and directed to the single end of monetary gain. The Reasonable Man is always thinking of others; prudence is his guide, and 'Safety First', if I may borrow a contemporary catchword, is his rule of life. All solid virtues are his, save only that peculiar quality by which the affection of other men is won. For it will not be pretended that socially he is much less objectionable than the Economic Man.

Though any given example of his behaviour must command our admiration, when taken in the mass his acts create a very different set of impressions. He is one who invariably looks where he is going, and is careful to examine the immediate foreground before he executes a leap or bound; who neither star-gazes nor is lost in meditation when approaching trap-doors or the margin of a dock; who records in every case upon the counterfoils of cheques such ample details as are desirable, scrupulously substitutes the word 'Order' for the word 'Bearer', crosses the instrument 'a/c Payee only', and registers the package in which it is despatched; who never mounts a moving omnibus, and does not alight from any car while the train is in motion; who investigates exhaustively the bona fides of every mendicant before distributing alms, and will inform himself of the history and habits of a dog before administering a caress; who believes no gossip, nor repeats it, without firm basis for believing it to be true; who never drives his ball till those in front of him have definitely vacated the putting-green which is his own objective; who never from one year's end to another makes an excessive demand upon his wife, his neighbours, his servants, his ox, or his ass; who in the way of business looks only for that narrow margin of profit which twelve men such as himself would reckon to be 'fair', contemplates his fellow-merchants, their agents, and their goods, with that degree of suspicion and distrust which the law deems admirable; who never swears, gambles, or loses his temper; who uses nothing except in moderation, and even while he flogs his child is meditating only on the golden mean.

Devoid, in short, of any human weakness, with not one single saving vice, sans prejudice, procrastination, ill-nature, avarice, and absence of mind, as careful for his own safety as he is for that of others, this excellent but odious character stands like a monument in our Courts of Justice, vainly appealing to his fellow-citizens to order their lives after his own example.

A.P. Herbert, [Uncommon Law].(http://en.wikipedia.org/wiki/Uncommon_Law). Emphasis mine.

I imagine that something of a similar sentiment animates much of popular hostility to LessWrong-style rationalism.