From the ama­zon synopsis: 

Why do smart peo­ple make irra­tional deci­sions every day? The answers will sur­prise you. Pre­dictably Irra­tional is an intrigu­ing, witty and utter­ly orig­i­nal look at why we all make illog­i­cal deci­sions. Why can a 50p aspirin do what a 5p aspirin can’t? If an item is “free” it must be a bar­gain, right? Why is every­thing rel­a­tive, even when it should­n’t be? How do our expec­ta­tions influ­ence our actu­al opin­ions and decisions?

I have not fin­ished this book yet but it definete­ly is one of the best books I’ve read for a long time. Dan Ariely clear­ly has opened my eyes: Hith­er­to I used not to under­stand intel­li­gent peo­ple behav­ing them­selves irra­tional­ly — like Ven­ture Cap­i­tal­ists ask­ing for prof­itabil­i­ty on one day and for reach only the other day (it’s just an example 😉

Now I com­pre­hend those irra­tional behav­iours as ‘the way it is’ (=pre­dictably). Irra­tional­i­ty is not a defi­cien­cy or even a prob­lem — no: it is a big part of the every­day life. You may declare this a trite insight but for me it was like an epiphany. Call it naïve — I’ve learned a lot.

epiphany insight irrational predictably irrational rational