Science & System

Johannes Kepler's platonic solid model of the Solar System, from Mysterium Cosmographicum, 1596. Public domain.

This blog post adapts elements of Thomas Kuhn’s and Paul Feyerabend’s theories of scientific progress and uses them as RPG theory. If that sounds boring as shit to you, bail out now.

Science and reality aren’t identical. Science is a body of knowledge that approximates reality to the greatest possible degree of accuracy.

RPGs perform a similar task. Instead of adhering to our lived reality, most RPGs approximate the workings of worlds that are imaginable but different from our own.

RPG systems and scientific paradigms both serve as models of possible realities. But they model those realities for different purposes.

Scientific Paradigms

Science serves as a model of the natural world. It explains observed phenomena, and it lets us make predictions about the future based on those observations. These models, explanations, and predictions are called paradigms.

When a paradigm’s descriptive or predictive power fails—when we observe phenomena that deviate from what science tells us should happen—then we’ve discovered a gap in that paradigm. We try to fill this gap by modifying or elaborating the existing model.

But if that approach fails, we must shift to a new paradigm. The change from the long-dominant geocentric cosmological model to the Copernican heliocentric model is one example of a paradigm shift. When Einstein’s general relativity supplanted Newton’s classical mechanics, that was another paradigm shift.

In both (and all other) cases, a new paradigm replaces the old because it (the new one) possesses greater accuracy. It provides a superior model for describing observed phenomena. The history of scientific milestones is the history of new paradigms.

RPG Systems

RPGs are models of imaginable worlds. We don’t use them to predict real phenomena; we use them to simulate the phenomena of RPGs’ imaginable worlds.

When a system’s simulative power fails—when it can’t do what we want, either efficiently or at all—we seek alternatives. We hack the old system, or we find or design a new one.

RPGs are pluralistic; they’re in economic competition for readers’ attention and money, but not for truth-value like scientific paradigms are. Systems don’t supplant one another the way paradigms are perceived to.

But even old paradigms can remain in play. We still use classical mechanics to launch spacecraft because it’s practical. It’s not the most accurate model of physics, but it gets the job done, and that’s what counts.

RPG systems work the same way. They coexist alongside one another, and we use whichever one provides the desired experience—and if not, we hack a system so that it will provide that experience.

The same thing occurs in science with ad-hoc postulates, which modify an existing theory or hypothesis. In science, the postulates augment a model to maintain consistency with observed phenomena; in RPGs, they modify the system to more adequately simulate the intended phenomena.

Normal Science & Third-Party Content

Normal science builds on an existing model. Normal science is research science; it elaborates a paradigm and widens its scope by extending its jurisdiction to new phenomena. The scientific community is mostly engaged in normal science.

If an RPG system is equivalent to a paradigm, then its normal science is third-party content. Third party content elaborates and expands a system the same way normal science does for a paradigm.

Third-party content falls into two categories: declarative and procedural.

Declarative content is about things: adventure modules, spell lists, gear, monsters. It adds stuff for you to use within the existing system.

Procedural content is about doing things. It adds mechanics that increase the system’s variety and versatility. It lets you play in new ways by modifying the existing system.

Third-party publications aren’t canonical, but they’re accessible; the content circulates in the community, gaining visibility and currency among fellow practitioners. The same dynamic is how scientific discoveries earn adherents and lead to practical and intellectual advances.


The holy grail of modern physics is the unification of relativity with quantum mechanics—models of very large scales and very small, respectively. Einstein died trying to reconcile them. Modern physicists still try.

But for the sake of illustration here, they are incommensurable. Each has a particular explanatory scope that doesn’t account for the other. You can’t use macrophysics to do microphysics, and vice versa.

The same is true of RPG systems.

Plenty of games have obvious genealogical relations, such as games that adapt the core d20 system; a die is rolled, modified, and measured against a target number. Examples and variations of this system are countless: Knave, A Dragon Game, Mörk Borg, and too many others to list.

Another common system comes from Lasers & Feelings. Whereas d20-based systems overwhelmingly (if not universally) feature multiple discrete attributes, Lasers & Feelings and its descendants use binary attributes on a continuum. Barkhäxan puts four stats on two continua, but it still uses the same fundamental structure.

These systems are incommensurable with one another. They use different mechanics to achieve their goals. Each one does certain things well, but it’s unable to do everything. Each model has its own inherent limits and gaps that restrict what it’s able to simulate (and how).

The systems mentioned above are also incommensurable with other, different ones such as the Year Zero engine, which uses dice pools. And all of these are likewise incommensurable—if not more so—with other materially distinct systems like Carolina Death Crawl’s card-based mechanics or Dread’s physical, kinesthetic block tower.

Scientific paradigms and RPG systems proliferate because each one works differently, and each allows us to perform different activities (or, at least, similar activities in meaningfully different ways).

The Consistency Condition

The consistency condition demands that if something isn’t unworkably broken, we maintain the status quo. It’s a reflex that mitigates cost and risk.

In both science and RPGs, it’s impractical to revise resources every time a modification is possible or desirable. Digital distribution has eased this problem to a certain extent, but even additions as small as a footnote in a science textbook or an errata update in an RPG still require time, effort, and funding.

For bigger fixes like new or revised game systems, RPG publishers have to invest even more money into development, testing, and distribution. Players have to invest in new books so they can then invest time and effort into learning a new or modified system.

Don Norman, in The Design of Everyday Things, sums up the situation: “If a new way of doing things is only slightly better than the old, it is better to be consistent. But if there is to be a change, everybody has to change.”

That change is inevitably costly, time consuming, and faces significant resistance; adherents will likely push back against the changes if for no other reason than being accustomed to the way things are.

The Eternal Return of Discourse

Science and RPGs behave similarly because they’re both discursive; they’re systems designed to structure experience. Saying “system doesn’t matter” is the equivalent of arguing that geocentric and heliocentric cosmologies’ differences are purely superficial. They aren’t. The differences are structural and significant.

As discourses, scientific paradigms and RPG systems construct worldviews. They structure the way we understand, interpret, and interact with a world. In the case of science, that world is lived reality, while RPG systems predominantly structure imagined worlds.

In both cases, structure doesn’t simply inform what we do; it determines what we can imagine and how we pursue our goals within that structure.

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