Ultimately I have to return to #Keynes c1933. where he related #liquiditypreference to a three dimensional relationship between the state of the news (#expectations), the #rateofinterest, and the quantity of #money. Fixing any one of these left the adjustment between the other two. In particular this thinking allowed the rate of interest to be determined exogenously. Perhaps the failure to grasp this is one factor behind the subsequent success of #ISLM
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So, it seems to me, that pretty much all the paraphernalia of economic theory can help explain is a structure of interest rates (#risk, #expectations, #profit, #liquiditypreference etc), but not its level or even what the level ought to be in terms of some Wicksellian natural rate. Or, like Picketty, we can look at historical norms.

Keynesian #liquiditypreference gives a sense to the structure of rates, the yield curve. It provides nothing in terms of the level. The mystery as to what might determine the #profit rate remains.