Descriptive theory, then normative. Correct? 

The article claims that
“Savage proved that, if you adhere to axioms of rationality,  if you believe an uncertain event has possible outcomes  each with a utility to you of  then your choices can be explained as arising from a function in which you believe that there is a subjective probability of each outcome is , and your subjective expected utility is the expected value of the utility…”

First of all, how can something like this be “proved”? It seems to be an empirical matter. But more importantly, the article later says, with regards to the failure of the theory to predict actual choices, that
“Savage's response was not that this showed a flaw in his method, rather that applying his method allowed individuals to improve their decision making.”

The first paragraph claims a descriptive role for the theory, but according to the second quote it is a normative theory about how people should reason. This problem is so flagrant that I have to question whether Savage ever actually made the first claim, since this one also contains the problematic claim of a proof. Could we either get a description more in line with Savage's own claim, or either a reference for this flaw?