
Originally Posted by
sarnamluvu

Originally Posted by
Achilleas

Originally Posted by
Daecon
I'd have thought economics was a branch of mathematics (statistics?) that's closer to chaos theory than a science.
Unfortunately, mainstream economics at least, does not use chaos theory. Well, in most cases economics doesn't even use dynamic analysis at all. Theory sticks to static equilibrium. Only some few heteredox schools of economic thought uses chaos theory, complex systems, non linearity, dynamics, etc.
The most complete economics models used by central banks, IMF and governments, the so called DSGE (dynamic stochastic general equilibrium) models are always in equilibrium. No chaos in here.
- the law of supply
- the law of demand
- elasticities
- market forms (,e.g. monopoly, oligopoly, monopolistic competition, etc.)
- externalities
- sunk costs
- short run and long-run costs
- the law of diminishing returns
- the minimum efficient scale
- economies of scale/scope
- the quantity theory of money
I do argue that these are not empirical facts. These are theoretical concepts, mostly derived from neoclassical school of thought. Through econometrics and basic statistics we can find all short of correlations. That doesn't lead to causality though.
Some comments:
Law of Demand (as a downward monotonous function) & Law of Supply (as an upward monotonous function) are invalid if we assume more than one person. ("sold quantities= bought quantities" is just a tautology and doesn't mean that D(p)=S(p)).
Elasticity is "just" the slope of a function, the derivative function (if we assume that the first function is differentiable). The empirical β, (in an econometric function) may represent various differently determined elasticities. A very useful tool, though.
Theoretical market forms may be determined by various ways. You refer to neoclassical forms of markets. The two core forms (perfect competition and monopoly) have several important fallacies (eg Sraffa's critique, Sononheim-Debreau-Mantel theorem, etc). Other school of thoughts may determine a market by comparing the long-term specific % of profit with the adjusting capital (determined by competition) ) Obviously, different theoretical market forms will lead to different observations.
The law of diminishing returns is a 100% theoretical concept and literally there's no way to estimate it since marginal products don't exist. Also, the various econometric functions based on Cobb-Douglas are rather problematic (for more, Shaikh has a great paper on that).
The Quantity Theory of Money. This is actually an old theory (since mid 1700s). In any case, money is an endogenous variable (especially money-commodity and credit money through the law of the reflux). QTM has several applications in specific cases (eg in certain cases in over"printed" fiat money) but in the way it is used (MV=PQ --> Ms=Md) it's rather problematic as well.
Son oligopoly doesn't exist? And yes, there are different modes of determining things, so what? this doesn't mean that the base concept is invalid.
Monopoly theory is much better than perfect competition, for sure. At least, it provides fertile ground for economic policy and state intervention. But, it has important fallacies derived from partial equilibrium, marginalism and neoclassical concept of competition. On the other hand in economic policy debates perfect competition still functions as the benchmark.
The neoclassical theory on it's core is individuals who maximize/minimize certain things (profit, utility, risk, etc). We could criticize the theory from numerous points of view. I'll just mention the most famous concept of neoclassical theory as an example. S=D.
Note that the law of the supply still doesn't function even under monopoly (have a look at Sraffa's late work & capital theory debates for more) for several reasons. You can't draw a supply curve since marginal products don't exist, Capital is not homogenous (this is a macro implication), etc Or you may draw a supply curve which is not upward moving. Also, you can't derive the Supply of capital. It is always assumed that capital is not produced at the current period (even though these models are static) so in the capital market you there's no a supply curve.
The law of Demand doesn't function for several reasons as well (if you're not familiar with the criticism let me know, I can post some more info- it's really interesting).
Most notably, Schonenheim-Debreu-Mantel theorem argues that each polyonimal derived from individual utility functions can function as an aggregate demand curve and literally, can have very strange shapes, not necessarily a downward slope. Furthermore, if we wanted to draw a downward demand function we should assume that each individual's Engel curves are parallel but, since Engel curves pass through O (0,0) we should assume that all individuals have the same Engel curve. Nonsense, it's like saying that each individual is the same replica of a given individual.
The problem is that neither aggrigate nor individual demand curves function as downward slopes.
These are just a few examples that I can recall without referencing to other sources. The critique can become much bigger.
Real sciences start on aggregate level. Also, all other social sciences start on aggregate level. (possible exception, psychology) Only neoclassical economics starts on the concept of individualism. If you dig a bit the core of the theory, you'll find the "axioms of revealed preference":
1) Completeness
2) Transitivity
3) non-satiation
4) convexity
Under these circumstances utility functions exist, etc.
Now, how can you argue that this is a science since indiference curves are unobervable? You create a "science" that its main axioms are about an unobservable thing.
Paul Samuelson did answer by creating the "revealed preference".
Some empirical research has been done (Sippel, 1995,1997). He askef from his students in the economic department to compare goods given a fixed income and write down their preferences. Later, he tried to draw their indiference curves. The key proposisions being tested were the "weak axiom of revealed preference" "strong axiom of revealed preference" and "general axiom of revealed preference". The results were smashing. None of these axioms are empiricaly correct.
Also, the maximisation under the constraint of income is unrealistic.
A blowmind example. Suppose that you enter a supermarket which has 100 commodities. Assume that you have 2 options related to quantity (buy/not to buy- no other quantities). Each commodity adds an extra dimension on your indiference curve.
So with 100 commodities and 2 options for each commodity you have:
2^100= 1,267,650,600,228,229,401,496,703,205,376 combinations.
like 1st combination: 1 beikon, 0 banana, 1 carrot, 1 DVD, 0 orange juice, 1 water bottle, 1 lager beer, 1 stout beer, 0 pizza, 0 batteries, 1 plastic fork,....... and so on.
If you add more options (0,1,2,3..,5 quantities of eg bananas, beers, etc) you have 5^100 combinations.
If you add more commodities (supermarkets have thousands) you have 5^1000 combinations.
A computer needs 3-5 years to calculate is utility function in a 50 commodities store with only 2 options.
Does anyone beleive that it is "rational" to compare so many combinations in order to find which basket maximizes the utility? it just doesn't scale to reality. Yet, you say the concept is valid.
My main argument is that economic sphere is certainly a subject of scientific research. But, not all schools of thought have scientific characteristics.
On the one hand, economy is described by conflicts, endless motion, institutional, social and historical changes.
On the other hand, neoclassical economics describe a harmonious, peaceful world were "rational"selfish agents in "free" markets act according to their very personal goals and all markets stabilize in their equilibrium simultaneously. There are no social classes, no conflict interests, no motion, no (historical and most times not even natural) time. No offense but, how can you say that this concept is valid?