Showing posts with label economics and mathematics. Show all posts
Showing posts with label economics and mathematics. Show all posts

Wednesday, August 2, 2017

Robert Paul Wolff — Mathematics in Economics

I think it is a mistake to ask whether economists should use mathematics. That is like asking whether an electrician should use a Philips screwdriver. The obvious reply is, For what? The really interesting foundational questions in economics can never be answered by introducing more sophisticated mathematical techniques, fun though they are. Before all else, one must decide what questions economics should be trying to answer.
Fir the tool to the job, not the job to the tool. Or to put it another way, if all you have is a hammer, every problem looks like a nail.

The Philosopher's Stone
Mathematics in Economics
Robert Paul Wolff | Professor Emeritus, University of Massachusetts Amherst

Sunday, July 30, 2017

Tim Johnson — Why mathematics has not been effective in economics

I have the opinion that almost all of the criticism of the use of mathematics in economics stems from a lack of understanding of what mathematics is, reflecting a general ignorance in economics that has led to the failure of mathematics in economics.…
The starting point of understanding the role of mathematics in finance and economics is to appreciate what mathematics is concerned with. Mathematics is concerned with identifying relations between objects: bigger smaller, to the left/right, symmetry, before/after and so forth. Top class mathematical research is concerned with discovering new ways of representing how things are related. More every-day research shows that A=B or how you go from A to B. Once the mathematicians have done their work, of "formatting the world as we experience it" by identifying how we see relations between objects, others then get on and do things.…
Mathematicians rely on other disciplines providing problems, mathematics, whatever the caricature of a mathematician dealing with abstract ideals will say. Mathematics then figures out a way of looking at the problem - the relations between its components - so that a solution can be found. The caricature of the mathematician is explained by how mathematics is presented. Rather than starting with the problem and then breaking it down into its components, mathematics is presented back to front. It starts with the components and then shows how these combine to deliver the observed phenomena.…

The effect in economics is most clearly seen in Friedman's argument, in theMethodology of Positive Economics, that the validity of an economic theorem should not rest on the realism of its assumptions. I will not dismiss Friedman as the arch-priest of neo-liberalism as I think the argument he makes has some merits (he focuses on the empirical outcome and would normally be regarded as 'anti mathematiciastion'). The attitude he shares with most economists, along with Kant, Hobbes and Spinoza, is that a 'mathematical' argument flows from assumptions to conclusions. A mathematician approach would be to try and tease out the correct assumptions from the observed behaviour. I would prefer the problem to be re-cast as "By fetishising synthetic a priori knowledge, economists turned economics into a highly paid pseudoscience".

The next question is why do economists do this. The answer is rooted in the observation that the 'mathematical' approach is powerful rhetorically: you can use it to convince everyone of almost anything, providing you can make the chain of arguments tricky enough to follow.…
Once mathematics has delivered ways of identifying relations in physics, 'invariants' can be identified, such as momentum, energy or the speed of light (Noether's Theorem is critical here). Physical theories are then tested on the basis of whether or not they adhere to a particular conservation law. Because economics is disinterested in using mathematics to identify relationships it has been unable to accomplish the next step of discovering invariants.…
Money, Maths and Magic
Why mathematics has not been effective in economics
Tim Johnson | Lecturer (associate professor) in the Department of Actuarial Mathematics and Statistics, Heriot-Watt University, Edinburgh

Sunday, August 21, 2016

Ari Andricopoulos — On Maths and Models

Every now and then a debate seems to flare up about economic models. A recent one started with Noah Smith arguing (in reply to Frances Coppola), that heterodox economics does not have the tools to replace mainstream economics. Steve Keen gave an excellent point by point reply about the mathematical quality of heterodox work. Then Frances also wrote a reply and then another, which  I agree with, pointing out that an understanding of the economy does not require maths. Where maths can be used to formalise this understanding, it is very useful. But economics is not a mathematical equation.
I say this from the point of view of someone with a PhD in mathematics, but whose job is to predict the behaviour of systems, specifically financial systems. And I know that in describing a system, parsimony is king. One should use as much maths as is necessary and not a bit more. The more complex the maths, generally the worse the predictive power.
The economy is a very complex system. It is non-linear with a huge number of unknowns. For this reason prediction is difficult. This seems to have meant that any degree of poor prediction is excused on the grounds that no-one can predict the future. I recommend everyone read this excellent Noah Smith blog post from 2013 which was only let down by the somewhat cowardly conclusion.  It shows DSGE models are not useful as predictions - he points to this paper showing that DSGE models are no better than simple univariate autoregression (AR) models at predicting inflation and GDP growth. Bearing in mind AR models are just simple mean reversion models this is a pretty categorical failure. He then argues that they are neither good for policy advice nor even for communication of ideas, before concluding that we should continue with them as the are the 'only game in town'.
Saying that the economy can't be predicted because it is too complex and no-one knows the future is a big cop out for me. No-one could have predicted with any degree of certainty that the global financial crisis would happen in 2008. This is because it is impossible to predict the timing of events of this nature that depend on triggers and positive feedback loops. It also depends on policy reaction. For example, a possible crash in China early this year was averted by a large government spending programme. But what heteredox economics has done is give keys to understanding the nature of the economy.…
Notes on the Next Bust
On Maths and Models
Ari Andricopoulos | Partner at Dacharan Advisory, Zurich, and PhD in Mathematics

Lars P. Syll — Steve Keen, Noah Smith and heterodox ‘anti-math’ economics

Responding to the critique of his Bloomberg View post on heterodox economics and its alleged anti-math position, Noah Smith approvingly cites Steve Keen telling us there is
a wing of heterodox economics that is anti-mathematical. Known as “Critical Realism” and centred on the work of Tony Lawson at Cambridge UK, it attributes the failings of economics to the use of mathematics itself…
Although yours truly appreciate much of Steve Keen’s debunking of mainstream economics, on this issue he is, however, just plain wrong! For a more truthful characterization of Tony Lawson’s position, here’s what Axel Leijonhufvud has to say:
Lars P. Syll’s Blog
Steve Keen, Noah Smith and heterodox ‘anti-math’ economics
Lars P. Syll | Professor, Malmo University

Saturday, August 13, 2016

Lars P. Syll and Ramanan reply to Noah Smith on the use of math in econ

Noah Smith — like so many other mainstream economists — obviously has the unfounded and ridiculous idea that because heterodox people like yours truly, Hyman Minsky, Steve Keen, or Tony Lawson, often criticize the application of mathematics in mainstream economics, we are critical of math per se.
I don’t know how many times I’ve been asked to answer this straw-man objection to heterodox economics– but here we go again.
Lars P. Syll’s Blog
Noah Smith — confusing mathematical masturbation with intercourse between research and reality
Lars P. Syll | Professor, Malmo University
So it is not that neoclassical economists have great mathematical tools. It’s that by failing to incorporate the framework of flow of funds, they are showing their incompetence in mathematical reasoning.
Math is a tool box filled with various tools fit for different purposes. The art of using tools involves not only knowing how to use each tool properly but also how to choose the right tool for the job.

The Case for Concerted Action
Economics Without Mathematics?
V. Ramanan

Note: Noah Smith is a troll.


Wednesday, May 11, 2016

Thursday, April 7, 2016

Jason Smith — The mathematics is not the issue here, Dude


Some interesting reflections by Jason Smith.

Instead of talking about math and "mathiness," perhaps we should speak about formalization of informal arguments and conceptual models in the interest of rigor. 

Humans think and communicate using ordinary language, which is product of evolution and consists of many alleys and byways as well as highways. As Ludwig Wittgenstein sought to show, ordinary language can be something of a minefield. Meaning is context-dependent. Failure to appreciate the use of signs in context leads to misunderstanding signs as symbols.

Wittgenstein explored rigorous expression before turning to ordinary language. The Tractatus was a response to Russell and Whitehead's Principia and also to Frege. Russell was so impressed he invited Wittgenstein to Cambridge.

The Tractatus as an exposition of the logic of description can be seen as a work not only about logic but also the philosophy of science. Wittgenstein was an engineer by training. His Tractatus was developed out of the introduction to Hertz's Principles of Mechanics.

Wittgenstein's work turned the focus of Anglo-American philosophy in the direction of analysis. There are arguably three periods in the history of Western philosophy. Ancient and medieval philosophy were chiefly absorbed in the question, What is there? In founding modern philosophy, Descartes pointed out that prior to answering this question, it is necessary to answer the question, What can we know about what is? Wittgenstein shifted the focus from thought to language, asking the question, What can we say meaningfully?

Formalization of language is an attempt to increase rigor in expression. However, it is not the only way, since logic is broader than formal logic and mathematics. Clear and precise expression is a challenge because the ordinary language that grounds our thinking process contains a lot of noise, and it is a temptation to confuse some of that noise with a signal.

The history of Western thought is generally traced to Socrates as his student Plato set forth the dialectical method in the Dialogues. It is clear that the method that Socrates employed was intended to clarify expression by introducing rigor through debate. This was the beginning of the scientific method, as it were. If one insisted instead in talking about gods, they were sent to the temple.

Science is usually thought as a being chiefly empirical, so Aristotle is credited with founding the scientific approach. But prior to observation is expression, and expression involves the use of signs as symbols. Getting clear on how language works is a prerequisite to gaining knowledge as the confluence of experience and understanding. Aristotle agreed. His works begin with the logical investigations, Prior and Posterior Analytics. Aristotle's logic can be viewed as a proto-formalization of logic implicit in the Dialogues.

Tradition has it that the lintel of Plato's Academy was inscribed with, "Let no one ignorant of geometry enter." The term "geometry" may have meant "mathematically literate" in context. Aristotle wrote in the Analytics that one should not talk "geometry" with those who are not geometrical, that is, not so inclined. This could be extended to mean that one should not attempt to be rigorous with those who are non-rigorous and who cannot deal with abstraction.

Descartes initiated the second great step in formalization in his Discourse on Method, the full title of which is Discourse on the Method of Rightly Conducting one’s Reason and Seeking Truth in the Sciences. "Clear and distinct ideas" are fundamental to correct method. 

Descartes was a mathematician as well as a philosopher. Descartes developed analytic geometry and Leibniz initially developed calculus, although it was Newton that usually credited. Formalization begins to incorporate mathematics, and mathematics is developed to support greater formalization.

Since then, the overwhelming view is that formalization in science is chiefly mathematical. This quite obviously followed since science is about measurement of quantity and changes in quantity. But basic logic still applies. You can't add apples and oranges, and the meaning of terms cannot shift within the same context. 

Occam's razor also applies: Let expression be as simple as possible for the task. This is where over-formalization and "mathiness" can come in. Is the exposition as simple as it could be to get the job done? Or is it being complicated as a matter of jargon that protects the trade?

I don't think any of this is controversial. Say what you mean as simply as possible and as rigorously as need be, and don't get pedantic. To the degree that a subject is amenable to quantification, the preferred method is to use math appropriately. Is there any argument about this?

Alfred Marshall advised economists to use math intelligently to clarify their thought and make their point.
I had a growing feeling in the later years of my work at the subject that a good mathematical theorem dealing with economic hypothesis was very well unlikely to be good economics: and I went more and more on the rules - (1) Use mathematics as shorthand language, rather than as an engine of inquiry. (2) Keep to them till you have done. (3) Translate into English. (4) Then illustrate by examples that are important in real life (5) Burn the mathematics. (6) If you can’t succeed in 4, burn 3. This last I do often. — Letter to A.L. Bowley, 27 February 1906, cited in: David L. Sills, Robert King Merton, Social Science Quotations: Who Said What, When, and Where Transaction Publishers, 2000. p. 151.
Keynes said of Marshall:
The study of economics does not seem to require any specialized gifts of an unusually high order. Is it not, intellectually regarded, a very easy subject compared with the higher branches of philosophy and pure science? Yet good, or even competent, economists are the rarest of birds. An easy subject, at which very few excel! The paradox finds its explanation, perhaps, in that the master-economist must possess a rare combination of gifts. He must reach a high standard in several different directions and must combine talents not often found together. He must be mathematician, historian, statesman, philosopher – in some degree. He must understand symbols and speak in words. He must contemplate the particular in terms of the general, and touch abstract and concrete in the same flight of thought. He must study the present in the light of the past for the purposes of the future. No part of man's nature or his institutions must lie entirely outside his regard. He must be purposeful and disinterested in a simultaneous mood; as aloof and incorruptible as an artist, yet sometimes as near the earth as a politician. Much, but not all, of this many-sidedness Marshall possessed. But chiefly his mixed training and divided nature furnished him with the most essential and fundamental of the economist's necessary gifts – he was conspicuously historian and mathematician, a dealer in the particular and the general, the temporal and the eternal, at the same time. John Maynard Keynes, Essays In Biography (1933), p. 170.
Keynes thought of economists as wearing many hats. This accords with the ancient conception of the philosopher as lover of wisdom. A philosopher studies the whole, regarding nothing as alien. Robert Heilbroner called the great economists "worldly philosophers." They are not only social and political scientists but also social and political philosophers.

I would say that the placing math on a pedestal in economics may tempt some economists to forget that that they are doing something other than natural science, which the conception of "market forces" is apt to convey if not designed to do so. Math is not a end in itself other than for those doing pure mathematics. Those who use math for other than pure mathematics are doing applied math. What they are doing may involve much more than math and even more than is quantitive, since human life is qualitative as well.

There is also pure science and applied science. Theoretician are dong pure science, while engineers are going applied science or technology. Engineering uses science as theoretical knowledge to make stuff. So it is an art. Some theoretical physicists are exploring the boundary of science and philosophy.

Economics also has theoretical and applied aspects. Theoretical economists explore model space. Applied economists attempt to make economics useful in explaining the world. Some applied economists also use economic to affect the affairs, e.g., through policy formulation.

Conflating pure and applied results in confusion. What holds in a model does not necessarily hold in reality. Exploring model space is interesting and important, but it is not the whole of the field.

Moreover, and most importantly, theoreticians may not be well qualified in areas of application, such as policy formulation. A noble prize in theory doesn't necessarily quality a person as a policy adviser.

It is also useful to remember that Ronald Coase received The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for "the Coase theorem," which is not expressed mathematically.

There is also a place for people like John Kenneth Galbraith that translated economics and politics economy into a level of expression that non-economists could understand and use in approaching policy.

Generally speaking, math cannot be used to sell an idea politically without appealing to argument from authority since most of the audience won't understand the math. Voters need to understand the rationale for policy and have criteria for evaluating it. Otherwise it is a matter of proliferating post hoc ergo propter hoc (before therefore because) fallacies.

There's a difference between buying a piece of technology that depends on complicated math and intricate science that very few have the capacity to understand and buying into to policy prescriptions based on "experts."

In summary, there is a need for rigor in expression. Math is one tool in the toolbox for achieving rigor. But just as tools can be applied to uses for which they are not fitted, so too can logic and math.

When this is unintentional, it is called ignorance. When it is intentional, it is called sophistry. So while rigor is a plus, user beware. Rigor is a only prerequisite — a necessary condition but not a sufficient one.

Information Transfer Economics
Jason Smith

Wednesday, September 2, 2015

Tuesday, May 26, 2015

Mark Buchanan — In Economics, What Calculates Isn't Always Right

This mathematical-purist approach came from a rather odd place. As Roy Weintraub relates in his excellent book "How Economics Became a Mathematical Science," Debreu took his perspective from a secret group of French mathematicians who, starting in the 1930s, worked under the pseudonym “Nikolas Bourbaki.” The Bourbaki group thought mathematics should have an almost religious purity, refined and unsullied by contact with the practical. Educated in Paris, Debreu came under their influence, and then shifted from mathematics to economics. 
Weintraub argues that Debreu played a decisive role in transforming economics -- “not only the field's self-image, but its concept of inquiry itself.” Ever since, economic math has been Bourbakian, primarily concerned with formal structure. Practitioners downplay the need for realistic assumptions, as Paul Fleiderer noted in his brilliant essay on chameleons. They use highly dubious suppositions to generate a result, which they then use as a foundation for giving advice to policy makers. This is pretty much the opposite of good science. 
Scientists generally enlist mathematics only as a tool, and ultimately value practical understanding above theoretical rigor. They care deeply about the plausibility of the assumptions used in any model. Models, of course, are always oversimplified -- one might say “wrong” -- but it's what they get right that matters. A sphere is a good model for the Earth not because it lacks any geographical detail, such as mountains or valleys, but because it gets the rough shape right. 
The Bourbakian influence in pure mathematics actually caused a rift between physicists and mathematicians back in the 1980s. The formal and pure Bourbakian approach seemed useless to the physicists, whose more practical approach seemed suspect to the mathematicians. Since then, that rift has disappeared as math has moved on. Economics apparently hasn't recovered yet.
Good article on how conventional economics got where it is. 

It's all in the head.

Bloomberg View
In Economics, What Calculates Isn't Always Right
Mark Buchanan

See also

Lars P. Syll’s Blog
Anti-Romer
Lars P. Syll | Professor, Malmo University

Sunday, May 24, 2015

Brian Romanchuk — Mathiness


In "Protecting the Norms of Science in Economics", Paul Romer writes: 
"About math: I have studied physics as an undergraduate.I’ve seen clear evidence that math can facilitate scientific progress toward the truth.  
"If you think that math is worthless or dangerous, I’m sure that there are people who will be happy to discuss this with you. I’m not interested. I’m busy."
I'll see his undergraduate degree in physics, and raise him by a Ph.D. in applied mathematics (Control Systems Theory). Undergraduate physicists study highly polished and elegant models which have been chosen because they describe aspects of physical behaviour quite well. Conversely, engineers study complex systems which may or may not appear to follow those simplified laws of nature*, and are forced to make educated guesses on how to simplify the analysis of the systems. Economics is dealing with complex systems that are a lot closer to the reality of engineering than the ivory tower of undergraduate physics. 
One needs to push down the expectations of what mathematics can accomplish. Mathematics consists of two things:....
May should like it is going to go all wonkish, but it doesn't.  Brain makes some killer points. Nice job.

Bond Economics
Mathiness
Brian Romanchuk

Thursday, May 21, 2015

Stephen Williamson — Don't get mathy with me, or I'll give you a good shunning


Stephen Williamson gets back to Paul Romer.

Stephen Williamson: New Monetarist Economics
Don't get mathy with me, or I'll give you a good shunning
Stephen D. Williamson | Robert S. Brookings Distinguished Professor in Arts and Sciences, Washington University in St. Louis

Tuesday, May 19, 2015

Monday, May 18, 2015

Sandwichman — Mathiness and Growthiness

The fundamental reason why we cannot do without dialectical concepts is that actuality, at least as seen by the human mind, continuously changes qualitatively. … —Nicholas Georgescu-Roegen, "Methods in Economic Science"
Like I've been sayin' in those same words.  And quality is more important in life than quantity.
In a 1981 commentary on Georgescu-Roegen's paper, Salim Rashid defended economists' persistence in undialectical methods as lying "not in their failure to appreciate the importance of dialectical logic, but in the institutional structure within which they live and work."
I would say this in terms of dialectical reasoning versus institutional arrangements in that dialectical reasoning incorporates institutional arrangements along with many other relevant factors in taking a holistic (systems) approach. Institutional arrangements are norms that generate priorities that can be analyzed quantitatively to a degree. But institutions are fundamentally qualitative, based on an organizational culture for example.

They follow dialectical logic, as Bill Black has been documenting regarding the behavior of the officers of TBTF banks. It is perfectly rational dialectically to pursue control fraud in an unregulated and unsupervised criminogenic environment where the stakes are huge and the potential for being caught, let alone punished, is small.

Conventional economists missed this, am most are still blissfully unaware of it, because they assumed away criminogenic environments, resultantly predictable based on historical precedent, in their chiefly quantitive approach based on restrictive assumptions, for example, in this case an overly restrictive definition of rationality and interest that rules the issue out. Subsequently, Fed chair (hence regulator in chief) Alan Greenspan later admitted his "mistake" after the horses had left the barn.

Sandwichman always write good stuff. If you are not following him, this is a good one to read if you are at all interested in the critique of conventional economics. It goes much fur there than a critique of Paul Romer's view of mathiness.

Econospeak
Mathiness and Growthiness
Sandwichman

David F. Ruccio — The fetishism of mathematics


As usual David Ruccio nails it (IMHO). Paul Romer hoist with his own petard.

Occasional Links & Commentary
The fetishism of mathematics
David F. Ruccio | Professor of Economics University of Notre Dame Notre Dame

Wednesday, April 29, 2015

Robert Heilbroner: “The prestige accorded to mathematics in economics has given it rigor, but, alas, also mortis”

“Economics is not a scientific discipline like the natural sciences, and that no cumulative advance describes its changeful form over the years… The chapter we call modern economics, compared with earlier chapters of our discipline, is shallow and poor rather than deep and rich, and that the intellectual puzzle of some future time will be to account for the failure rather than the success of the period in which we have lived… The prestige accorded to mathematics in economics has given it rigor, but, alas, also mortis.” (Heilbroner 1979: 193, 196)
Economic Sociology and Political Economy
Robert Heilbroner: “The prestige accorded to mathematics in economics has given it rigor, but, alas, also mortis”
Oleg Komlik | founder and editor-in-chief of the ES/PE, Chairman of the Junior Sociologists Network at the International Sociological Association, a PhD Candidate in Economic Sociology in the Department of Sociology and Anthropology at Ben-Gurion University, and a Lecturer in the School of Behavioral Sciences at the College of Management Academic Studies