There's a long tendency for people to be attracted to simple ideas. Many believe that there are easy solutions to tricky problems - be they independence, a smaller state, getting companies to pay fair taxes, whatever. (Yes, Marxism used to be among such ideas.) There's a name for this - the Casaubon delusion, the notion that there's a key to all mythologies.But, as several millions corpses in the 20th century warn us, such keys often don't exist. Foxes (pdf), who know many small things, do better than hedgehogs who know one big thing.
However, the opposite of a great truth is another great truth. In other contexts there are indeed simple solutions or near-solutions.Gerd Gigerenzer has shown (pdf) that simple rules of thumb are surprisingly effective, and evidence from many different contexts supports the claims of Robyn Dawes (pdf) and Paul Meehl (pdf), that simple models often out-perform expert judgment.


However, there is popular resistance to the use of such simple methods. Very few stock-pickers rely solely upon simple screens* and our attitudes to management - especially among the political-media class - haven't progressed beyond "ju-ju man do magic."

So here's the paradox. We often believe in simplicity when we shouldn't, and don't believe in it when we should. John Stuart Mill said that liberty is often granted when it should be withheld and withheld when it should be granted. The same, perhaps, applies to simplicity.

*1:リンク先(cf. リンク先のサイトオーナーのWikipedia)には以下のように書かれている:
In George Eliot's Middlemarch, Edward Casaubon spends his life in a futile attempt to find a comprehensive explanatory framework for the whole of mythology. He is writing a book which he calls the Key to all Mythologies. This is intended to show that all the mythologies of the world are corrupt fragments of an ancient corpus of knowledge, to which he alone has the key. Poor Mr Casaubon is, of course, deluded. His young wife Dorothea is at first dazzled by what she takes to be his brilliance and erudition, only to find, by the time he is on his deathbed, that the whole plan was absurd and she can do nothing with the fragments of the book that she is supposed to put into order for publication.
In honour of Mr Casaubon, I have given this tendency of the mind to search for all-inclusive answers the name Casaubon delusion.


*3:cf. ここ

*4:cf. ドーズのWikipedia。なお、ディローのリンク先はリンク切れだったので、同論文の別のリンク先にリンクしている。

*5:原注:This might be reasonable for professional fund managers as such strategies carry benchmark risks, but retail investors have no such excuse.(そうした戦略はベンチマークリスクを伴うのでプロのファンドマネージャーにとっては妥当かもしれないが、一般の投資家にはそうしない理由はない。)