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Hey there econ forces, subscribed to leave a comment, but also because you write good articles and it's worthwhile to discuss this stuff. I don't mind supporting your work at all.

I have really been trying to leave the mainstream people be, because I do think they do good work, and are making honest efforts. A lot of heterodox critiques aren't really helpful or specific, just blanket attacks. So first of all, I don't want be just randomly disparaging you guys or mainstream ideas in general. I want to be specific.

What the supply and demand model does is separate analysis into independent perspectives of buyers and sellers. You create one graph of seller price responses, and another for buyer price responses. Where those curves intersect is the current clearing price.

The limitation is when there is feedback, then the two curves aren't independent. The buyer response curve is diverges from the market price, rather than being fixed independently, and similarly for sellers.

In particular, for financial assets, buyers and seller don't really have distinct independent criteria. Both are assessing future value to try to buy the assets that will go up in price, and sell the assets that are going down. You can't really silo people trading financial assets into the buyer side or seller side. It's the information that matters, not whether someone is looking to buy or sell.

For real assets that get consumed, you inherently have different perspectives between producers and consumers, which translates well to the supply and demand model. It's not perfect, and there is still feedback, where people adjust their bids and asks according to price history, but it is useful to separate these two perspectives for analysis.

The problem is that many macroeconomic models, going back to IS-LM, are versions of supply and demand, but for financial assets. Just because a depth chart of an order book looks like supply and demand, does not mean it's a good model. There's no way to analyze buyers or sellers independently, and that's why IS-LM, as well as more modern version of AD-AS, fail to be effective.

A lot of back and forth with heterodox folks happens because people on both sides don't invest in understanding the other view, before attacking it. In general, there is no obligation to investigate something you don't think has merit, but if you do try to critique something in detail, then you should at least make a good faith attempt to understand it.

The post Keynesian perspective does have a lot of merit, and in particular Perry Mehrling does a really good job of teaching money in a way consistent with post-keynesian thinking. He has a great MOOC.

A lot of the critiques of supply and demand are when it is used tautologically, like with financial assets. The supply and demand model just lets you isolate price dynamics into two perspectives, but you then have do the exact same analysis from the buyer side or seller side, whether that is cost plus, or marginal utility, or whatever.

Also, it gets complicated when you talk about actual market orders in an order book, versus the counterfactual response of buyers or sellers when prices change. In general, I think cost plus has a lot of merit, and is not inconsistent with a supply curve, it's a way to build a supply curve.

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