Noah Smith has some smart things to say about libertarians and property rights...

...and you should probably read the whole thing, but I wanted to single out this passage:

That's right: irreducible transaction costs are a fly in the libertarian soup. Completing an economic transaction, however quick and easy, involves some psychological cost; you have to consider whether the transaction is worth it (optimization costs), and you have to suffer the small psychological annoyance that all humans feel each time money leaves their bank account (the same phenomenon contributes to loss aversion and money illusion). Past a certain point, the gains to privatization are outweighed by the sheer weight of transaction cost externalities. (Note that transaction costs also kill the Coase Theorem, another libertarian standby; this is no coincidence.)

This dovetails nicely with this discussion about why the decision-making processes of engineers and scientists are often 'irrational' in the strict economics sense of the word. Like transactions, decision-making algorithms have a cost. In most cases, these costs are fairly small (like the few seconds it takes to decide on a brand of beer) and you can get away with ignoring them, but freshwater economists routinely make arguments for rational behavior that require people to make incredibly complicated calculations almost instantly. What's worse, they continue to make these arguments even when data suggests that people are using other, simpler rules to make their decisions.