September 21, 2019

What’s wrong with DSGE models is the axiom set

Comment on David Glasner on ‘What’s Wrong with DSGE Models Is Not Representative Agency’


“When the premises are certain, true, and primary, and the conclusion formally follows from them, this is demonstration, and produces scientific knowledge of a thing.” (Aristotle)

Standard microeconomics is based on these hardcore propositions, i.e. verbalized axioms: “HC1 economic agents have preferences over outcomes; HC2 agents individually optimize subject to constraints; HC3 agent choice is manifest in interrelated markets; HC4 agents have full relevant knowledge; HC5 observable outcomes are coordinated, and must be discussed with reference to equilibrium states.” (Weintraub)

Because this set of hardcore propositions is shock-full of NONENTITIES all models that are based upon it are proto-scientific garbage. The whole of Marginalism derives ultimately from the core behavioral assumption HC2, i.e. constrained optimization, which is a NONENTITY like the Tooth Fairy or the Easter Bunny. From the Walrasian axioms, the triad SS-function―DD-function―equilibrium is derived. All ends up eventually in General Equilibrium Theory.

Because the behavioral axioms are false the whole of mainstream economics is false. This includes DSGE because it is just a variant of HC1 to HC5. The common denominator is that the axioms are behavioral. For deeper methodological reasons, which have been discussed elsewhere, macroeconomics has to be based on objective, behavior/agency-free, systemic axioms.

This is the correct core of premises: (A0) The objectively given and most elementary systemic configuration of the economy consists of the household and the business sector which in turn consists initially of one giant fully integrated firm. (A1) Yw=WL wage income Yw is equal to wage rate W times working hours. L, (A2) O=RL output O is equal to productivity R times working hours L, (A3) C=PX consumption expenditure C is equal to price P times quantity bought/sold X.

These premises are “certain, true, and primary” and therefore satisfy all methodological requirements. The set is minimalistic, that is, Occam’s Razor has been applied and the set cannot be reduced further, only expanded. The set contains no NONENTITIES like maximization or equilibrium and no normative assertions. All variables are measurable with the precision of two decimal places. Testability is built into the premises.

The price P follows as the dependent variable under the conditions of budget-balancing, i.e. C=Yw, and market-clearing, i.e. X=O, as P=W/R. This is the most elementary form of the macroeconomic Law of Supply and Demand. Accordingly, the real wage is W/P=R. The graphical representation of the macro-economy is given on Wikimedia AXEC31.

Elementary production-consumption economy

The monetary saving/dissaving of the household sector is defined as S≡Yw−C. The monetary profit/loss of the business sector is defined as Q≡C−Yw. It always holds Q≡−S, in other words, the balances of the business and the household sector always add up to zero. This is the Fundamental Law of Macroeconomic Accounting.

The mirror image of household sector saving S is business sector loss (-Q). The mirror image of household sector dissaving (-S) is business sector profit Q. Q≡−S is the elementary version of the macroeconomic Profit Law.

Given the minimalist core propositions (A0) to (A3), one has to proceed top-down by successive DIFFERENTIATION of sectors and firms until one arrives at the individual agent. The bottom-up approach, also called microfoundations, is methodologically false because it is (i) behavioral, and (ii), runs with necessity into the Fallacy of Composition. (A0) to (A3) fully replaces HC1 to HC5.

Economics is in need of a Paradigm Shift from false Walrasian microfoundations and false Keynesian macrofoundations to “certain, true, and primary” macrofoundations. Or as the Financial Times has it “Time for a reset.”#1

Egmont Kakarot-Handtke

#1 Links on “Capitalism. Time for a reset.”

Related 'DSGE and profit―forget it! MMT and profit―forget it!' and 'The Ur-Blunder of economics and its rectification' and 'Economics: How to stop mental pollution and global dumbing' and 'The curious non-existence of profit in economics' and 'Where economics went wrong (II)' and 'The GDP-death-blow for the economics profession'. For details of the big picture see cross-references Axiomatization.

For more on DSGE see AXECquery

Mike Norman Economics Sep 23

Source: Mike Norman Economics


Wikimedia AXEC137b Axioms/Macrofoundations


Twitter Feb 12  “The problem lies ... with its core axioms.”

Source: Twitter


INET Mar 8, 2021  Servaas Storm, The Standard Economic Paradigm is Based on Bad Modeling