Link broke
What can one say? Humans have been struggling with the notion of reason or rationality for untold moons now, and a solid definition has not been attained. If anything , we have learned that our behavior is often very illogical and contradicts most definitions of reason that have been proposed. It is probably best to leave the notion of rationality out of the mix and just be content with studying and comprehending human behavior before attempting a definition of a rational being.
Really simple and informative graph.
One thing I really like about it is that the level of confidence of the most expert expert, is not the highest point of the plot.
The answer is "2", for the graph figure is merely 2 turned on its side.
Here's a (hopefully) interesting thought. On average, all things being equal, is not reading instruction manuals a sign of the Dunning-Kruger effect in action?