The Simulation Hypothesis is the hypothesis that we might live in a (computer) simulation within a similar or rather different world.
I make a distinction between regular simulations and irregular simulations. Regular simulations are worlds governed by simple laws and elegant of physics and do not allow for direct interference of the simulators while the simulation is running. Irregular simulations break at least one of those conditions: That is
- Irregular simulations might follow very weird laws of physics
- The simulators intervene in the simulation while it’s running
- There might even be multiple layers of physics and reality, all of them interacting in possibly highly complicated, chaotic, and dynamic ways
Further, I make the distinction between obviously irregular simulations and subtly irregular simulations. In obviously irregular simulations it’s rather obvious that things are highly “fishy”: There are gods that talk with you, or the laws of nature appear highly chaotic.
In subtly irregular simulations it’s not clear at all that the simulation is irregular. Instead, it looks like a regular simulation superficially. Detecting anomalies that hint at the irregular character of the simulation is hard. There may even be mechanisms in place that make detecting such anomalies virtually impossible for normal inhabitants of the simulation. If anything, some inhabitants have the suspicion that something is not quite right and that there is more “between heaven and Earth” than people suspect.
What could be present in subtly irregular simulations?
- Seemingly supernatural / paranormal phenomena without clear natural explanation
- Psi powers or magical powers that are usually very weak
- Higher powers subtly influencing the course of history
- Mystical creatures being real, but really hard to provably detect (mythical beasts, ghosts, spirits, gods, extraterrestrials)
- Hidden layers of reality only weakly interacting with the regular layer of reality
In other words: Crazy stuff that science doesn’t want us to believe in does actually exist in a subtly irregular simulation, since it’s added consciously (or by accident) by the simulators.
Now let’s come to the purpose of this hypothesis: It could actually be used to “explain” the weird stuff going on in our world, especially the paranormal stuff that isn’t easily explained away by science and critical thinking. The value of such explanations depends on their complexity and the probability that we actually live in a subtly irregular simulation. “Supernatural” stuff done by incomprehensible gods for opaque reasons has very high complexity, while simple hacks make by comprehensible simulators for logically sound reasons have relatively low complexity. Good explanations should have minimal complexity while explaining as much as possible.
What’s the probability that we live in a subtly irregular simulation? That’s hard to tell. We would need to know whether simulators are more likely to simulate regular or irregular simulations. Since we aren’t at the stage of development that would allow us to simulate large complex worlds in realistic detail, we can only speculate at the moment. Once we become simulators on our own, we would be in a better situation to estimate the probability that we live in a certain kind of simulation (if at all).
Are there any plausible reasons at all to create subtly irregular simulations? I think so:
- Simulators might be bored with all the regular simulations they have already done and “spice things up” by including weird stuff
- Simulators might want to test complex hypotheses by introducing specific irregularities into their simulations
- Simulators might not be sure whether they live in a subtly irregular simulation and therefore do several ancestor simulations of their own world. Among regular simulations they also do irregular variations to find out which of them approximates their own history best. This is probably the most conclusive way to find out whether one lives in a subtle irregular simulation or not!
- Simulators might want to accelerate the “progress” going on in their simulations and include “irregular factors” that help life and civilizations to advance faster
- Perhaps simulating irregular simulations is “cheaper” (more energy efficient or whatever) than doing regular simulations
- Whatever utility their simulations may have, it’s plausible to assume that cleverly chosen irregular simulations may have higher utility than regular ones – for most definitions of “utility” at least
So, there doesn’t seem to be a lack of motives for creating (subtly) irregular simulations.
Do I believe that we live in a subtly irregular simulation? No, I am agnostic about that. I just think that this is a very interesting hypothesis, which could possibly make sense out of the things that don’t make sense in our world. As such, it’s however a tempting short cut to simply “explain” mysterious stuff with us living in an irregular simulation, rather than doing a thorough scientific analysis of the weird phenomenon in question. On the other hand, science may indeed suffer from a bias when it doesn’t even consider the possibility that the irregular simulation hypothesis could actually be true!
Apart from that, the irregular simulation hypothesis is a marvellous device for creating fascinating, compelling, and rationally validated fictional worlds and stories containing weird “magical” stuff! 
Arguably, that has to do with different people having different implicit ontological models of the world. And the models of most people aren’t really good, because most people aren’t serious philosophers. I think the notion of being able to “unexist” something that has existed by travelling to a further past and changing history is logically inconsistent. That is because people reasoning about time argue from the inside of time, not from outside of it! Logic, existence, and mathematics are outside of time, not inside of them (ok, that’s my model of reality and people are free to disagree). When existence is outside of time, it cannot be undone by operations within time!
