...so I thought it was worth collecting them.
PrometheeFeu writes: "I think part of the problem is that this may not be emphasized enough in economics college courses. My international relations courses made a big deal of the fact that our models were just tools to understand the world from the very first day of IA101. My economics courses felt like they were making a big deal that people are rational agents."
I have a couple thoughts. The first is agents are rational in the colloquial sense of the term. Some people try to change this into meaning that they're emotionless or that they don't have diverse goals, but I think that's a misleading use of the word. Plus economists are usually not using it in the colloquial sense and have something specific in mind, and that's worth keeping in mind too. As for the point generally I of course can only fight anecdote with anecdote - but I've racked up quite a few anecdotes over the years and my experience is completely the opposite. Economists in my experience are very good at emphasizing that their models are just useful abstractions to illustrate a particular mechanism.
S/he continues: "Maybe it's just anecdotal, but then there is the fact that in many studies, econ students do behave much more rationally than their peers, happily violating social norms in the name of optimization."
Selection effects are very important here. Certain types of people choose to take economics. I'd also wager the anecdote is an overstatement. And finally, a lot of the empirical evidence on this comes from experimental economics games. To me, that just says that economics students know the theory behind the games and they know how powerful some anonymous, unrepeated defection can be. Insofar as that's the evidence, I'd be wary of generalizing that to behavior in the real world (which, I understand, kind of shoots a hole into the whole point of experimental economics).
Elliott had the most bizarre comment of all: "Policy setters attempting to "de-complicate" the system based on recommendations stemmed from mainstream economic models -- I imagine this is what pisses everyone off -- the reality of "uncertainty" and "entrepreneurship" by themselves should shine a light upon delusional recommendations stemmed from the notion of state enforced common good"
My experience is that it's usually precisely we economists who are the only ones telling policymakers that they are not capable of achieving this. Come on guys - it's the old Hayek line about how the task of economists is "is to demonstrate to men how little they really know about what they imagine they can design"
Charles Rice says: "I agree right up to the part where you said "to develop testable predictions""
This gets to my long-standing point about explanation versus forecasting (and "prediction" is admittedly an ambiguous word). Forecasting a complex system is very hard, whether it's the weather or the economy. We can do OK at forecasting using a process that Charles describes: throwing a bunch of lags and polynomials of a bunch of variables into a model and seeing what gets spit out. That's often what forecasting amounts to. If you're a trader that has its place, but its not economic science because you're not really learning anything about the processes of the economy. I would not be as caught up with forecasting as Charles's comment is. I'm more concerned with testable predictions about the behavior of data. He goes on to say we should bet on our conclusions... I've never understood the fascination with prediction markets. A few interesting bets here and there always makes things interesting, but I don't see what's necessary about that.
Unlearningecon says: "I think the difference is that there is only one variable that the algae adjust to here, whereas when humans make decisions there are a lot of different influences."
I disagree with the first part of the sentence and agree with the second part. Then he goes on to essentially blame the financial crisis on mainstream economics, which is nuts because mainstream economics is giving us the best explanation now of what all happened.
Min provides another head-scratcher: "First, evolution is a satisficer, not an optimizer. It's survival of the fit, not the fittest. Herbert Spencer did not get it right. In fact, some of the best evidence for evolution is the lack of optimality."
Right. But Min, you seem to have an odd view of the objective function of a maximization problem. It doesn't have to be "maximize my strength subject to these constraints" - that would be the (false) optimizer view of evolution (as you put it). If the objective function is simply to pass on genes subject to constraints - and particularly if those constraints involve a degree of path dependence - you have a satisficer version of evolution. This is what bugs me about critics of mainstream economics who hate the idea that everyone is motivated by profits, for example. Fine! Put something else in the objective function! Mainstream economics is a framework for approaching a problem. I've never heard anyone say "if you don't think people are solely interested in maximizing profits you can't be a mainstream economist". Dierdre McCloskey, great as she is, makes this mistake a lot.
Min goes on: "When the environment changes at the same rate as the organism, the result can be chaotic. Human systems in which agents are adapting to each other can be chaotic, as well."
Well, right Min! Min is a lot like Charles Rice above... I think half the reason why s/he disagrees with me is because s/he thinks I'm saying something that I'm not.
What takes the cake is that Min shares this link about how Russ Roberts butchers a discussion of biology and economics: http://mikethemadbiologist.com/2011/03/21/when_economists_misunderstand/
Clearly Min is unaware that I harangued Russ over EXACTLY this post and I made most of the points that Mike makes here. Mike argues that economists should be careful when they talk about biologists. The same is true in reverse (although physicists are the absolute worst when it comes to thinking they know something about social science). Clearly Min is assuming I'm saying things that I'm not saying.
Introduction to Algorithms, Lecture Three
1 hour ago