Dualism in Science, Theology, and Economics

I’ve spent a lot of time on this blog debunking economists’ claims about productivity. Usually, I come at the problem from a fairly technical angle, meaning I break down the contradictions involved in economists’ methods. Today, I want to try a more philosophical approach. I’m going to talk about dualism — the idea that something can be two things at once.

Dualism in science

Science is filled with dualist statements — claims that a substance is two things at once. Of course, scientists don’t use this terminology. They call their dualist statements ‘mathematical equations’. Here’s a famous one from Albert Einstein:

\displaystyle E = mc^2

In this equation, Einstein claims that matter and energy are two sides of the same coin. In other words, there is some mysterious force that can convert matter into energy and vice versa.

Because mass-energy equivalence sounds pretty wild, Einstein’s equation gets a lot of attention. But science is rife with conceptually identical statements. For example, Newton claimed that there is something called a ‘force’ that can be converted into ‘acceleration’:

\displaystyle F = ma

When you reflect on these equations, you realize that they are making rather profound metaphysical claims about the world — much like claiming that the Father, the Son and the Holy Ghost are the same thing. So were Einstein and Newton just doing theology?

No. They were doing science.

Unfortunately, most introductory science textbooks don’t explain the distinction. Instead, they take a rather theological approach to pedagogy. Textbooks often present formulae as received wisdom, and then tell students to explore the consequences. Similarly, many science popularizers know that the public is hungry for metaphysics, and so they discuss the ‘profound’ implications of various theories. But what popularizers rarely do is explain why scientists trust the formulas they use.

Part of the problem comes down to mathematical notation itself. On its own, a mathematical equation is not science. It is a definition. For example, I can define a quantity F that is the product of mass times acceleration:

\displaystyle F = ma

Until I test this equivalence, however, I haven’t done science. To do science, we must treat our mathematical definition as a mathematical question. Unfortunately, there is no accepted notation for this way of thinking. But perhaps it might look like this:

\displaystyle F =? ~ ma

To test this equation/question, we devise ways of independently measuring both sides of it. Now, by ‘independently’, I don’t mean measurement that is ‘theory free’, since that’s impossible. All measurement depends on preconceptions about the world. (To measure the length of different objects, for example, you assume that the length of your ruler remains constant.) In science, ‘independent’ measurement simply means we use methods that don’t depend on the theory we are testing.

So if we are testing Newton’s equation, we can’t measure force in terms of acceleration. Instead, an independent measurement might be something like this:

  1. measure force with a spring gauge,
  2. measure mass with a balance scale
  3. measure acceleration using the change in velocity over time.

These measurements all depend on preconceptions about the world. But they do not logically imply Newton’s equation. And so if we find that force is the product of mass times acceleration, we’ve shown that Newton’s equation is not merely a human definition. It is a truth statement about the natural world.

We can do the same thing with Einstein’s equation — albeit using tools that are more complicated. For example, in 2005, Simon Rainville and colleagues used atomic-mass differences to test the equivalence of matter and energy. They found that Einstein’s equation was accurate to seven decimal places.1

Again, it is the experimental confirmation that renders an equation meaningful. Without the observational component, we are left with nothing but a human definition. And that brings us to theology.

Dualism in theology

If science is the combination of logical definitions with empirical observations, theology is science without the observation. It is a web of human definitions, and nothing more.

As an example, take the Catholic concept of the Trinity, which is notorious for its bizarre logic. According to church dogma, God exists simultaneously as ‘The Father’, ‘The Son’ and ‘The Holy Spirit’. But while these three entities are all God, they are somehow distinct from each other. Thus the Holy Spirit is God. And the Son is God. But the Holy Spirit is not the Son. Confused? That’s because the Trinity is logically incoherent. But don’t worry, the church says it’s be true.

Figure 1: The Shield of the Trinity. Wikimedia Commons

The Trinity is a prime example of theological dualism. We have a set of definitions, and nothing else. Sure, you can argue about the definitions. But there’s no objective way to settle the score. Quarrels over the Trinity are the medieval equivalent of debates in modern fandom. It’s like when Star Wars fans argue about whether Anakin Skywalker ‘died’ when he became Darth Vader. The correct answer is that there is no correct answer. The ‘truth’ is however you define it.

Although it makes for abysmal science, the theological stance is a great way to sound authoritative while you spout bullshit. The self-styled libertarian ‘philosopher’ Ayn Rand was a master of this technique. Here she is laying out her philosophy of objectivism:

The formula defining the concept of existence and the rule of all knowledge: A is A. A thing is itself. You have never grasped the meaning of [this] statement. I am here to complete it: Existence is Identity, Consciousness is Identification.

Rand’s writing is a tour-de-force in theological nonsense. Start with a tautology (A = A). Follow it up with some weighty definitions (existence = identity). Claim you have a ‘rule for all knowledge’. Marvelous bullshit.

Dualism in economics

Perhaps the best definition of economics is that it is ‘secular theology’. Economics adopts the veneer of science, but, like theology, is based on untestable definitions.

In economics, the most pervasive dualism is the equivalence between income and productivity:

\displaystyle \text{income} = \text{productivity}

Unlike Ayn Rand’s poetic bullshit, the dualism between income and productivity is meant to be quantitative and literal. In neoclassical economics, a person’s income indicates their contribution to society.

Like all good theology, the theory starts with a definition. If Alice has some output Q that is sold at some price P, her gross income is defined as:

\displaystyle I = Q \cdot P

For example, if Alice grows 10 apples and sells them for $1 each, her gross income would be $10:

\displaystyle I = (10 \text{ apples }) \cdot ( \$1 \text{ per apple} ) = \$10

If Alice grew half as many apples, her income would be cut in half:

\displaystyle I = (5 \text{ apples }) \cdot ( \$1 \text{ per apple} ) = \$5

From this angle, it seems like the duality between income and productivity is sound. The problem is that it is actually unnecessary. If we can count what Alice produces (apples), we can measure her productivity directly. So we don’t need income.

Worse still, if the price of apples changes, not only is the income-productivity duality unnecessary, it is also false. For example, if Alice grows the same number of apples each year, the reality is that her productivity is constant. And yet if the price of apples changes, we infer from her income that her productivity has changed. That’s just wrong.

So right off the bat, we have a logical problem with the productivity-income duality. Either it is correct but unnecessary, or it is both unnecessary and incorrect. Either way, the duality is unsound.

Of course, there is nothing wrong with having a hypothesis that is logically unsound. It just means that when you notice the problem, you should abandon the hypothesis. But that’s not what happened in economics. Instead, the income-productivity duality became the basis for the entire system of national accounts.

Along the way, economists invented various fairy tales to justify their theology. For example, in the late 19th century, the economist John Bates Clark tried to ‘prove’ that in a competitive market, each agent earned what they produced. To his credit, Clark realized that the only way this proof worked is if everyone produced the same commodity. The problem is that this assumption renders Clark’s hypothesis moot. If everyone produces the same commodity, we can measure their productivity directly, meaning we don’t need income.

It gets worse. In the real world, where people produce many different commodities, we cannot measure productivity directly. (We cannot compare apples and oranges.) And so economists infer productivity by measuring income. But in this situation, Clark’s proof breaks down.

To address this logical problem, economists have invented more theology. Prices, they claim, are themselves a duality. Prices are both a monetary quantity and a measure of utility:

\displaystyle \text{price} = \text{utility}

So yes, prices may change, but that’s because the underlying utility of a commodity has changed. Or maybe it hasn’t. The problem is that economists never measure utility. They infer it from prices. And so the whole operation becomes circular — a theological definition, and nothing more. Joan Robinson nicely summarized the situation:

Utility is a metaphysical concept of impregnable circularity; utility is the quality in commodities that makes individuals want to buy them, and the fact that individuals want to buy commodities shows that they have utility.

In other words, economists propose a definition, and these use this definition to justify itself. That’s theology, folks.

The dualism smell test

Since both science and theology appeal to dualism, it can be difficult to distinguish the two forms of thought. With that in mind, here’s a dualism smell test.

Dualism always starts with a definition. Force is mass times acceleration. The Son is God. Income is productivity. To distinguish between science and theology, you should look at what follows the definition. In the case of science, the definition should be followed by an empirical test. Thus, scientists didn’t just take Newton at his word. They tested his laws of motion and found them to be correct (at non-relativistic speeds).

Now, the wonder of mathematics is that by manipulating algebraic definitions, you can derive predictions that follow from the starting assumptions. It’s important to test these predictions. But if they hold, that doesn’t mean that the assumptions are correct. That’s why scientists always test both the predictions of a theory and its assumptions. The classic example is Newton’s theory of gravity. When combined with his theory of dynamics, you get a rich set of predictions — enough to send people to the moon.

These correct predictions, however, didn’t stop scientists from testing the core assumption — the claim that inertial mass is equivalent to gravitational mass (a dualist statement). Indeed, this ‘weak equivalence principle’ has been tested continuously for more than four centuries. No one has found a violation.

When people like Milton Friedman spout theological nonsense, they’ll try to convince you that assumptions don’t matter. Friedman notoriously claimed that if a theory gives ‘correct predictions’, that’s good enough. Don’t believe him. Assumptions are the most basic part of science. If they are wrong, the whole theory is garbage.

Speaking of Uncle Milton, that brings me to theological dualism. When you do theology, the goal is to use a definition to (seemingly) prove your point and to avoid the fact that you are not testing your definition. One of the more amusing applications of this technique is in supposed logical ‘proofs’ of God’s existence. My favorite proof comes from Rene Descartes and goes something like this:

  1. God is perfect.
  2. It is more perfect to exist than to not exist.
  3. Therefore, God exists.

Do you see what Descartes did here? He used two definitions to make his point. He defined God as perfect. He defined existence as more perfect than non-existence. Presto, God exists.

Sorry, Rene, that’s not how it works. You’ve got to test your assumptions.

Is God ‘perfect’? Hard to say, since God is unobservable and ‘perfection’ is a subjective aesthetic. And is it ‘more perfect’ to exist than to not exist? Again, there’s not much to test here since we’re talking about aesthetics. But mathematicians might disagree. Only imperfect circles exist (in the real world). Yet mathematicians can imagine perfect ones. So maybe it is ‘more perfect’ to not exist.

In short, dualism fails the smell test if it is not followed by an empirical test. If there is no such test, what you have is not science … it is theological rot — a web of interlocking definitions that tell us nothing about the natural world.2

Support this blog

Economics from the Top Down is where I share my ideas for how to create a better economics. If you liked this post, consider becoming a patron. You’ll help me continue my research, and continue to share it with readers like you.


Stay updated

Sign up to get email updates from this blog.

This work is licensed under a Creative Commons Attribution 4.0 License. You can use/share it anyway you want, provided you attribute it to me (Blair Fix) and link to Economics from the Top Down.

[Cover image: Wikimedia Commons]

Want to know more about how economists equate income with productivity? Here are five pieces on the topic:

  1. No, Productivity Does Not Explain Income
  2. Productivity Does Not Explain Wages
  3. Productivity and Income … Again
  4. Debunking the ‘Productivity-Pay Gap’
  5. Real GDP: The Flawed Metric at the Heart of Macroeconomics


  1. Rainville and colleague’s experiment worked as follows. They let an atomic nucleus capture a neutron, after which the nucleus emits a gamma ray. To test Einstein’s equation, Rainville compared the mass change between the reactants and product to the energy of the gamma ray.

    The experiment is an interesting case-study in how measurement depends on theory. To measure the energy of the gamma ray, Rainville used the Planck relation, which describes how the energy of a photon relates to its wavelength. The measurement of wavelength, in turn, depended on Bragg’s Law of diffraction. And to measure mass, Rainville used cyclotron resonance. Converting the resonance frequency to mass depends on both Newtonian mechanics and the theory of the electromagnetic Lorenz force.↩︎

  2. Okay, theology does tell us something about the natural world. It demonstrates that the human species is adept at fooling itself.↩︎


  1. Blair, This one was priceless (as all the best things actually are, of course), really good. I always wondered how is it that one could have a father and a son with no mention of a mother — either in religion, or in human productivity, where she has uniquely valueless maximum utility, just like the holy spirit! When clerics or economists really need something, you just know it will come out of the air.

    • The first question has an accepted answer. Newtonian dynamics break down at high speeds and at small scales.

      The second question is more controversial. The dominant assumption is that Newtonian dynamics (gravity specifically) hold at galactic scales, but that unobservable dark matter affects the movement of visible mass.

      I think an assumption that is better supported by evidence is that at very low accelerations, Newton’s theory of gravity breaks down. Two blogs that describe this research:

      1. Triton Station
      2. The Dark Matter Crisis

      I think what you’re hinting at is that scientific equations are almost always shown to be wrong in certain circumstances. This issue points to deep philosophical debates about what scientists should do in the face of falsifying evidence. In the case of quantum theory, scientists abandoned the old paradigm (Newtonian dynamics) and proposed something new. In the case of galaxies, most scientists continue to accept the old paradigm, but have added an auxiliary (dark matter) to save the theory.

      As the blogs above demonstrate, the natural sciences are not immune to sociological issues. If anything, I’d argue that from Galileo onward, the theory of gravity remains the best case study in the philosophy of science.

    • Because of the realities of the power curve. It works mechanically in flight but also can be applied to social contexts and perhaps is the basis for bell curves of all sorts, even fashion, in clothing, politics, econ, tourism, etc. — kind of like Diana Vreeland’s concept of “wretched excess”. Not very intellectual but makes the point.

    • 《He who can digest a second or third Fluxion, a second or third Difference, need not, methinks, be squeamish about any Point in Divinity….  [W]ith what appearance of Reason shall any Man presume to say, that Mysteries may not be Objects of Faith, at the same time that he himself admits such obscure Mysteries to be the Object of Science?》

      — George Berkeley, “The Analyst”, 1734

      《Only yesterday, when the Chief Circle (in other words our High Priest) came to inspect the State Prison and paid me his seventh annual visit, and when for the seventh time he put me the question, ‘Was I any better?’ I tried to prove to him that he was ‘high,’ as well as long and broad, although he did not know it. But what was his reply? ‘You say I am “high”; measure my “high-ness” and I will believe you.’ What could I do? How could I meet his challenge? I was crushed; and he left the room triumphant.》

      — Edwin A Abbot, “Flatland: A Romance of Many Dimensions”, 1884

      《Nothing is gained from clinging to the scientific method, or to any methodology except honesty, clarity, and tolerance. Nothing is gained because the methodology does not describe the sciences it was once thought to describe, such as physics or mathematics; and because physics and mathematics are not good models for economics anyway; […]》

      — Deirdre McCloskey, “The Rhetoric of Economics”, 1983

      《In the end, a theory is accepted not because it is confirmed by conventional empirical tests, but because researchers persuade one another that the theory is correct and relevant.》

      — Fischer Black, “Noise”, 1986

      • I disagree with your “aphoristic” argument if I understand it correctly. I don’t think because you can’t measure the scientific method, it does not follow that mainstream economic models are any more valid. The article in question is about the dualism that exists in both scientific and economic models and how each aims to solve the internal contradiction. I think you have confused reality with a theory of reality.

    • Liam said:

      《it does not follow that mainstream economic models are any more valid.》

      Was I not clear enough that both economics and science are equally faith-based?

      I.e. didn’t the epicyclists use empirical tests to disprove Aristarchus’s heliocentric theory? Why did geologists ignore for so long the 2cm per year expansion of Iceland’s rift valley (not to mention the glaringly obvious observational evidence that South America and Africa once fit together, which any kid looking at a globe could see)?

      Why is dark matter still accepted even though no empirical test can detect it? Is String Theory theology because it cannot be tested?

      In short, do physicists only observe what they are looking for?

      Also, Blair says:

      《when you notice the problem, you should abandon the hypothesis. But that’s not what happened in economics. Instead, the income-productivity duality became the basis for the entire system of national accounts.》

      So why does Blair continue to use GDP as if it means something? Does he have faith in it, just because it’s easy to access in his databases?

      • I don’t use real GDP, rsm, which economist assume measures economic output. However, on occasion, I do use nominal GDP, which is just one (of many) measures of national income.

Leave a Reply