This is a guest post by Logan Chipkin.

Introduction

So many ideas that we take for granted had once been considered revolutionary. Historically, common responses to founders of such ideas have been charges of heresy, ostracism, or death. Famously, Socrates was sentenced to die for "corrupting the youth", which is a euphemism for his genius Socratic method. Effectively, Socrates was killed for popularizing the very idea of discourse --- a concept now so deeply ingrained in Western Civilization that it hums unexamined in the background, silently serving as the primordial soup from which all other new ideas emerge. And its earliest champion was killed over it.

Socrates is far from the only example. Nineteenth century physicist Ludwig Boltzmann received harsh criticism for using the conceptual atom in his theoretical work, and it is thought that this contributed to his suicide at the age of 62. He has since been vindicated, and the atom is widely accepted by scientists and laypeople alike.

There is no dearth of these tales. But if history is riddled with awesome ideas that are not appreciated until long after their origins, could there be such ideas floating about right now, under our noses?

There are. In fact, I can think of three ideas that are so deep, so potentially useful, and so paradigm-shifting that widespread acceptance of even one of them would transform civilization for the better. I musingly call these 'The Big Three': critical rationalism, praxeology, and constructor theory.

Critical rationalism

Critical rationalism is our best theory of knowledge and how it can grow. The twentieth century philosopher Karl Popper spent his career developing and advocating for it across books, essays, and lectures. The theory is concisely summarized in the title of a compendium of his essays: All Life is Problem Solving. As people, we face problems --- conflicts between ideas, to quote the physicist David Deutsch. This is true not only in science, but in our personal lives, in economics, and it's even true for both genes and creatures of the biosphere. The theory is as deep as it is wide --- critical rationalism applies anywhere in nature where knowledge can be found.

How do people solve problems? They conjecture solutions. For the scientist, this takes the form of creating explanations, or hypotheses, of some physical phenomenon. For the entrepreneur, this could be offering an original product to the market. For the gene, this could be a mutation that allows it to spread at the expense of its rivals (to be sure, this process is not conscious). Notice what these cases have in common --- something genuinely novel has entered Reality. Before Einstein's theory of general relativity, no one ever held the thought that "space-time tells matter how to move; matter tells space-time how to curve", to quote the physicist John Wheeler. Before the invention of the wheel, there were no such objects in the entire Universe. And biology is well-known to create chemicals that do not exist anywhere else --- proteins, for example, can't be found in the dark oceans of the cosmos, and yet they abound on Earth, in the presence of life.

But if we are only ever guessing solutions to problems, how can we be sure of ourselves? We can't. Here was another stroke of genius by Popper. The quest for foundations, for certainty, was itself a mistake. In science, for example, even our most basic presumptions are forever tentative, forever liable to revision and improvement. We can never know how a new theory will change our worldview, and so no assumption is perfectly secure.

Typically, more than one solution is conjectured to solve a given problem. By the 1600s, for example, there were two rival explanations for the motion of falling objects: that of the ancient Greek philosopher, Aristotle, and that of the contemporary thinker, Galileo Galilei. Aristotle held that objects fell at a speed proportional to their weight, while Galileo conjectured that all objects fall at a uniform rate, independent of their weight. What to do in such a problem-situation in which more than one solution is offered? Popper explained that we criticize all candidate solutions. This step is itself a creative process, as our methods of criticism and criteria for what constitutes a good explanation are themselves ever-evolving and improving.

In science, the most salient form of criticism is the so-called crucial experiment. When two or more theories attempt to explain the same phenomenon, we conduct an experiment whose outcome contradicts the predictions made by all but one of the rival theories. In the case of Aristotle's and Galileo's explanations of falling objects, the test was straightforward --- drop objects of different weights from some height and record their time to impact. Famously, if only apocryphally, Galileo did just that by dropping balls from the Leaning Tower of Pisa. Veracity of this tale aside, only Galileo's theory was in fact shown to be consistent with experimental outcomes. Aristotle's explanation of motion was banished from the scientific community and relegated to the history books.

And so critical rationalism holds that we conjecture as many solutions as we want, criticize all of them, and retain those that survive. Even after some scientific explanation survives scrutiny, its shortcomings are eventually exposed, and we must conjecture new solutions yet again. Galileo's theory was soon improved and brought into a much deeper explanatory framework by the seventeenth century physicist, Isaac Newton. And Newton's theory was further superseded in the early twentieth century by both quantum mechanics and Einstein's theory of relativity. The scientific process is open-ended, as problems are latent in all of our theories, and we are forever trying to solve problems in our worldview, to resolve errors in our theories.

In general, the scientific method proceeds as follows: whatever our current understanding of the world is, it invariably contains gaps and misconceptions, and there are phenomena for which it cannot account. We then conjecture a new theory that resolves at least one such flaw in our worldview. We criticize that theory with all of the tools at our disposal, only one of which is experimentation. For example, we demand that the new theory is internally consistent, not arbitrary, and so on. A theory that fails those criticisms doesn't need to be corroborated by experimental evidence. Only when we have multiple candidate theories to explain the same phenomenon do we conduct the crucial experiment. Once we have criticized all available theories, we retain whichever have survived. But we then find ourselves in a new, deeper problem-situation, for even with our updated worldview, there remain gaps in our understanding of Reality --- some that would never have even been previously conceivable. The entire scientific scheme in the critical rationalist framework is shown in Figure 1.

Figure 1. Diagrammatic representation of Popper's critical rationalism. Discover a problem/unexplained phenomenon, propose several potential theories/solutions (TS1, TS2, etc.), criticize all potential theories/solutions until one remains, eliminate errors/explain phenomenon by applying the surviving theory/solution, discover new problems (P21, P22, etc.), repeat.

Many of the so-called crises in science today are a result of bad philosophy --- that is, of ignoring critical rationalism. In contrast to much of what is done in research, we cannot simply gather more data and hope to better understand Reality. Rather, we must first conjecture an explanation --- or several rival explanations --- and then criticize all such candidate theories. Data serves as a mode of criticism --- theories make different predictions about how the world ought to behave, and those theories whose predictions are inconsistent with data are said to be falsified, while those theories whose predictions are consistent with data are said to be corroborated. Moreover, it is logically impossible to 'go from data to theories', since interpreting a set of data is itself a theoretical act. So no amount of data-gathering can help us to solve problems absent some good explanation of what we expect to observe. Rival philosophies, such as empiricism --- which emphasizes only what we can observe --- and inductivism --- which claims that we proceed from observations to theories --- are false. So much effort is wasted by researchers and thinkers who are stuck in these mistaken frameworks.

So acceptance of critical rationalism would save many scientific fields that have stagnated in the last few decades, because researchers would reorient away from the overemphasized activity of gathering data towards the overlooked but fundamental activity of explaining reality.

Because critical rationalism shifts the emphasis from data to problems and conjectured solutions, the philosophy reaches far beyond science and into other important areas, such as how to live. A state of unhappiness is a problem-situation, and conjecturing explanations of why one is in such a state can inform a person as to what action to take. If the action still fails to resolve the problem, the person can conjecture yet another solution, and so on, in a trial-and-error fashion. A person continuously takes action in striving to go from problem-situation to better problem-situation. In fact, all of life takes this form, even if only implicitly.

Praxeology

Economics was always destined to be treated differently than the hard sciences. Unlike physics and chemistry, in which the objects of study are predictable systems like stars, planets, and metals, economics is a science of people --- and people are themselves creative, and hence unpredictable even in principle. This is cause for concern only for those who think that the goal of science is prediction. But as we've seen, critical rationalism implies that the goal of science is rather to solve problems in our worldview, to explain Reality. Prediction, then, is merely a way of testing, of criticizing theories. So the fact that people are inherently unpredictable is no problem for the critical rationalist.

Nevertheless, the astonishing effectiveness with which physicists had been able to predict the motion of objects ranging in size and speed from bullets to planets made an impression on thinkers in other fields. And critical rationalism was only discovered in the last century, so scientists and philosophers alike were vulnerable to all sorts of misconceptions that Popper's ideas would eventually resolve. In the meantime, predictions, mathematics, and sensory experience were thought to be fundamental to all sciences.

But, following Popper, our goal is to explain Reality with whatever tools we have at our disposal. The methods used by so-called Austrian economists are a priori and deductive --- they begin with an axiom so self-evidently true that to deny it would entail a self-contradiction. They then proceed to deduce logical implications of that axiom. In this way, no experiment could contradict their conclusions, because they were founded and deduced by logic alone.*

The Austrian school of economics was founded by the Viennese Carl Menger with the publication of his 1871 book, Principles of Economics. Menger and a few others ushered in the 'marginal revolution' in economic thought, so-called because they recognized that goods are consumed 'at the margins', an idea that solved the diamond-water paradox. Why is water typically cheaper than diamonds, if the former is more fundamental to human survival? The first generation of Austrian economists realized that 'water as such' and 'diamonds as such' are never consumed by the economic actor. Rather, a person consumes either a unit of water or a unit of diamonds at the margins --- he purchases whatever he values the most at a particular moment in time, after all of his lower values have already been satisfied. So, even though water is more biologically necessary than are diamonds, if John has already satisfied his desire to hydrate, then the next purchase he may prefer is a unit of diamond, rather than another unit of water. People make choices at the margins of their present scale of values. Value, then, is not intrinsic in any scarce resource, but rather is in the eye of the economic beholder. This subjectivist approach to economics contradicted both Adam Smith's classical school and the nascent Marxist view.

But how could anyone be sure that Austrian economics is correct, and those rival theories false? In physics, we could conduct a crucial experiment, as had been done successfully many times by that point in history. Enter Ludwig von Mises, arguably the greatest economist of all-time. In his 1949 magnum opus, Human Action, Mises elegantly derived --- and explained --- the entire edifice of Austrian economics via praxeology, the science of human action.

Mises' praxeology begins with the irrefutable axiom that man acts purposefully (I welcome the reader to reject the axiom and notice what happens). It is astounding how many conclusions follow. For example, in acting purposefully, it is immediately implied that John has chosen to pursue end A rather than end B. Had end A been unavailable, John would have indeed pursued end B. In this way, the action axiom implies the scale of values mentioned above. Furthermore, pursuing end A requires the use of some means, which, because they are being directed towards end A, they cannot be directed towards other ends. In other words, man acts in a world of scarce means. Because time is a scarce resource, then, all else being equal, man prefers to satisfy his ends sooner rather than later. In this way, the concept of time preference is derived.

Mises goes on to apply this way of thinking to ever more complex scenarios, starting with one man alone on an island to a society with diverse individuals desiring a multitude of ends. Through this deductive approach, he shows how prices emerge, the role of profits and losses in an economy, and, crucially, the damaging effects of coercive intervention into an economy of free actors.

I am only scratching the surface of what Mises accomplished. From first principles, he not only built an entire edifice of economic thought, but he also provided the explanation for why this school, the Austrian school, is the only correct one. After Mises, the Austrian school and its praxeological methods were here to stay, even though they remain the object of dismissal or mockery by economists from other schools of thought who demand that economics be empirical.

Murray Rothbard took the baton from Mises and continued developing Austrian economics. He also applied it forcefully to politics, creating the legal philosophy of anarcho-capitalism. Libertarianism had been defended in various forms in the past, but no one had unified praxeology, morality, and the concept of private property so thoroughly. In doing so, Rothbard spawned his greatest brainchild --- a consistent and elegant defense of a society without government and any other violations of the so-called nonaggression principle.

What Mises and Rothbard have demonstrated is that understanding is not limited to experimentally testable explanations. The dogma that scientific theories must be mathematical, and must make predictions about how objects will behave, is false. And with respect to politics, Austrian economics suggests that no government intervention may possibly improve the overall standard of living of mankind, to put it mildly. The ideas of these great men have radical implications that can be summarized in nine words:

You cannot coerce your way to a better world.

Constructor theory

The last of the Big Three is the youngest but perhaps the most fundamental. Constructor theory is officially less than a decade old, if the clock starts with the publication of its foundational paper in 2013 by physicist David Deutsch.

As with most of our deepest theories in physics and elsewhere, constructor theory's beauty is in its simplicity. That's not to say that the details wouldn't take effort to understand, but it's not some impenetrable labyrinth of mathematics and jargon. You don't have to be an expert in physics or epistemology or anything else to understand the ideas behind and within constructor theory.

In what Deutsch calls the prevailing conception of physics, theories take the form of 'initial conditions plus laws of motion'. For example, Newton's physics, called classical mechanics, allows you to predict an object's future position and momentum (mass times velocity) as long as you know all of the forces acting on it, as well as its current position and momentum. As we've seen, the success of Newtonian physics and other physical theories to predict a system's behavior over time was so impressive that predictive ability became a standard by which future theories would be judged.

In the 1800s, the theory of electromagnetism, while explaining a different class of phenomena than did Newton's theory, also took the form of 'initial conditions plus laws of motion'. In this case, the motion of charged particles, such as electrons, could be predicted if one knew the forces acting on them, and again, their initial state.

Even with the advent of general relativity and quantum mechanics in the 20th century, this paradigm reigned supreme. Although the state of a system was no longer necessarily expressed in terms of its position and momentum, the theories were still cast in terms of trajectories over time. Even in the notoriously weird quantum mechanics, something called a wavefunction evolved predictably over time, given particular laws of motion for that wavefunction.

So theories were thought to be all about what actually happens in the world. To reiterate, given some state of the world at any point in time, a successful theory, it was thought, should predict (or retrodict) the state of the world at some other time. In this prevailing conception, a theory provides equations of motion that predict what will happen to some system, given some current state, or initial conditions, of this system. Whether this system is a ball rolling down a hill, or the entire universe itself, or a quantum wave function, the prevailing conception is all about predicting what will happen to the system in question.

But some of our deepest explanations simply don't conform to this prevailing conception. Consider the other two of The Big Three --- critical rationalism and praxeology. In neither case do we predict the future according to some equation coupled with data of initial conditions. And, funnily enough, as I'd mentioned, one of the criticisms of praxeology is that it does not employ such equations! But the point is that some of our deepest theories of Reality simply cannot be expressed in terms of the prevailing conception. If Reality is as unified and comprehensible as most scientists fully expect it to be, then there has to be a way of formally unifying those theories that do conform to the prevailing conception, such as the ones I'd mentioned earlier, with these other theories that cannot be put in terms that the prevailing conception can handle. Other examples of the latter, by the way, include evolution by natural selection and computation.

So if our worldview is ever going to encompass both the wildly successful theories that do conform to the prevailing conception, as well as all of our theories that explain higher level phenomena --- such as praxeology and critical rationalism --- then we need some new theory, one that provides a language in which we can express all of the theories in the prevailing conception, as well as our other theories. This theory, it turns out, is constructor theory.

A final preliminary note --- there is a host of principles that most working scientists accept, but that are only implicit and cannot be expressed in any of the prevailing conception's theories. The principle of testability, that a theory must be falsifiable, is one such example. Until constructor theory, people just took that as a methodological rule, a rule of how science ought to be done. But constructor theory naturally and elegantly makes this principle explicit. Another example that seems to hold true but that the prevailing conception has no room for is the so-called Turing Principle, which essentially states that it is possible to build a computer that can simulate any physical process.

These two principles, along with others, have no place in the prevailing conception, because they're not about initial conditions and predicting the future state of a system. In fact, they're about what's physically possible and what's impossible.

This leads us to the governing idea of constructor theory --- that is, all of the laws of physics can be expressed in terms of which transformations are possible and which transformations are impossible, and why.

So while theories that conform to the prevailing conception will tell you the trajectory of the state of a system according to some laws of motion and given some initial state of a system, constructor theory tells you which trajectories are possible according to that theory, which are impossible, and why. While in the prevailing conception, what matters is what will happen, constructor theory is all about what can be caused to happen in principle. What actually happens is only an emergent consequence of what can possibly happen.

As a brief example, in Einstein's famous theory of special relativity, no object with mass can travel faster than the speed of light. And so in the prevailing conception, you have some object and its initial velocity, and the equations of special relativity can tell us the object's velocity at any future point in time. In those equations, it turns out to be impossible for the object's velocity to ever exceed the speed of light in a vacuum.

In constructor theoretic terms, we can say that the object's velocity cannot be transformed into a velocity that's greater than the speed of light, or, equivalently, that transforming an object's speed into a speed that's greater than the speed of light in a vacuum is an impossible task.

In that example, we don't get much purchase by switching to constructor theoretic terms, because the prevailing conception already has a handle on the phenomenon at hand. But what about questions that we can ask about other aspects of Reality? For example, under what conditions is life possible, in principle? That certainly can't be answered by the prevailing conception. How about: what resources are required to build a universal computer --- a computer that can simulate any other computer? There's no way we can answer these questions in terms of initial conditions plus laws of motion, but we might be able to answer them in terms of possible and impossible transformations. For example, maybe it's impossible for life to emerge in the absence of a genetic code, or any other sort of code. Maybe that can be shown under constructor theory. Maybe constructor theory can also show exactly under what conditions a universal computer can be built.

There are all sorts of questions that one can ask once one understands the power of constructor theory. And notice that the theory brings in counterfactuals into fundamental physics. In other words, what's fundamental is not what actually happens, but rather what could've been caused to happen. So what's interesting about, say, a computer, is not that it runs a particular program, but that it could be caused to run other programs.

And since constructor theory can just as well account for theories in the prevailing conception, as I had briefly shown with my special relativity example, we see that the prevailing conception is really just a limiting case that allows for classes of phenomena that do conform to an 'initial condition plus laws of motion' kind of theory. Constructor theory allows for a much wider class of phenomena, including those that are unpredictable in principle, those that require counterfactuals to explain, and those that can't be explained by resorting to a reductionist framework, in which we explain greater, bigger, or more complex phenomena in terms of their constituent parts. All of this is possible because of the single genius idea that all of the laws of physics can be expressed in terms of transformations that are possible and transformations that are impossible, and why.

Constructor theory is several decades younger than the other two of the Big Three, and so many of its accomplishments remain to be discovered (but read here, here, and here for scientific problems it has already solved). Still, constructor theory has many philosophical implications for our worldview, and even for our understanding of the role of people in the cosmos. Consider all of the transformations that are capable of being caused. Of those, only an extremely tiny minority occur 'naturally' --- there are few unique objects there are across the universe. Stars, planets, black holes, asteroids, and a whole lot of cold, dark, and empty.

Now consider what people have created in just the last few thousands of years. People have converted rocks into cathedrals. They've mixed the fiery energy of the sun with the guts of Earth itself to produce the orderly, purposeful devices that prevail in our digital age. They've turned wolves into dogs, trees into books, and metal into vehicles that fly through space. And the set of transformations that people are capable of causing is limited by what they know how to do. It follows, then, that both people and knowledge are fundamental in a constructor theoretic understanding of Reality --- only people are capable of causing any transformation capable of being caused, and their repertoire at any moment is limited by their knowledge.

Constructor theory also demands that we be philosophical optimists. Any problem that we face requires some transformation of our environment from the problematic state to an unproblematic state. But, as we've seen, people can render any transformation permitted by the Laws of Nature, so long as they acquire the requisite knowledge. It follows that any problem we face is necessarily solvable (see Deutsch's 2011 book, The Beginning of Infinity, for a longer discussion), it is just a matter of creatively discovering the solution.

Conclusion

The Big Three are available for anyone to study. I have merely introduced them in this article. Each of them contains so much more than I've offered in these brief pages.

Widespread understanding of any of The Big Three would resolve so many errors in our collective consciousness. Taken together, The Big Three constitute a revolution in the making on par with any of those that came before. There are numerous connections between them, but that's for another essay. The curious reader might already be putting the pieces together.

Socrates himself could never have imagined that our understanding of Reality might deepen and unify to such an astonishing degree. Although we remain infinite in our ignorance, our knowledge is deeper than in any age past. And yet, here we are, sitting atop a goldmine of mind-bending explanations. Best get digging.

*An open problem is how praxeology can be said to be empirical, if it is deducible from logic alone. This is one of the ways in which The Big Three come together, but that is a story for another essay.

Logan Chipkin is a freelance writer and ghostwriter in Philadelphia. Follow him on Twitter for more content like this.