What is a Simulation?

While reading Paul Rosenbloom’s outstanding book “On Computing” I came across an interesting question: what is a simulation, and how is it different from an implementation? I posed this question on Facebook and, thanks to the superlative quality of my HiveMind I had a productive back-and-forth which helped me nail down a tentative answer. Here it is:

‘Simulation’ is a weaker designation than ‘implementation’. Things without moving parts (like rocks) can be simulated but not implemented. Engines, planets, and minds can be either simulated or implemented.

A simulation needs to lie within a certain band of verisimilitude, being minimally convincing at the lower end but not-quite-an-implementation on the other. An implementation amounts to a preservation of the components, their interactions, and the higher-level processes (in other words: the structure), but in a different medium. Further, implementation is neither process- nor medium-agnostic; not every system can rise to the level of an implementation in any arbitrarily-chosen medium.

A few examples will make this clearer.

Mario is neither a simulation not an implementation of an Italian plumber. If we ran him on the Sunway TaihuLight supercomputer and he could pass a casual version of the Turing test, I’d be prepared to say that he is a simulation of a human, but not an implementation. Were he vastly upgraded, run on a quantum computer, and able to pass as a human indefinitely, I’d say that counts as an implementation, so long as the architecture of his mind was isomorphic to that of an actual human. If it wasn’t, he would be an implementation of a human-level intelligence but not of a human per se.

A digital vehicle counts as a simulation if it behaves like a real vehicle within the approximate physics of the virtual environment. But it can never be an implementation of a vehicle because vehicles must bear a certain kind of relationship to physical reality. There has to be actual rubber on an actual road, metaphorically speaking. But a steam-powered Porsche might count as an implementation of a Porsche if it could be driven like one.

An art auction in the Sims universe would only be a simulation of an art auction, and not a very convincing one. But if the agents involved were at human-level intelligence, that would be an implementation of an art auction. Any replicated art within the virtual world wouldn’t even count as a simulation, and would just be a copy. Original art pieces within a virtual world might count as real art, however, because art doesn’t have the same requirement of being physically instantiated as a vehicle does.

Though we might have simulated rocks in video games, I’m not prepared to say a rock can ever be implemented. There just doesn’t seem to be anything to implement. Building an implementation implies that there is a process which can be transmogrified into a different medium, and, well, rocks just don’t do that much. But you could implement geological processes.

Conway’s Game of Life is only barely a simulation of life; it would probably be more accurate to say it’s the minimum viable system exhibiting life-like properties. But with the addition of a few more rules and more computing power it could become a simulation. It would take vastly more of both for it to ever be an implementation, however.

My friends’ answers differed somewhat from the above, and many correctly pointed out that the relevant definitions will depend somewhat on the context involved. But as of March 29th, 2017, I’m happy with the above and will use it while grappling with issues in AI, computing, and philosophy.

Does Biology Drive ‘Pebble Formation’ in Ideologies?




Pebble Form Ideologies

(Epistemic Status: Riffing on an interesting thought in a Facebook comments thread, mostly just speculation without any citations to actual research)

My friend Jeffrey Biles — who is an indefatigable fountainhead of interesting stuff to think about — recently posited that the modern world’s aversion to traditional religion has exerted a selection pressure on meme vectors which has led to the proliferation of religions masquerading as science, philosophy, and the like. For any given worldview — even ostensibly scientific ones like racial realism or climate change — we can all think of someone whose fervor for or against it can only be described in religious terms.

Doubtless there is something to this, but personally I’m inclined to think it’s attributable to the fact that there are religion-shaped grooves worn deep in mammalian brains, probably piggybacking on ingroup-biasing and kin-selection circuitry.

No matter how heroic an attempt is made to get people to accept an ideology on the basis of carefully-reasoned arguments and facts, over time a significant fraction of adherents end up treating it as a litmus test separating the fools from those who ‘get it’. As an ideology matures it becomes a psychological gravity well around which very powerful positive and negative emotions accrete, amplifying the religious valence it has in the hearts and minds of True Believers.

Eventually you end up with something that’s clearly substituted ‘God’ for social justice, the free market, the proletariat revolution, etc.

An important corollary of this idea is that the truth of a worldview is often orthogonal to the justifications supplied by its adherents. I’m an atheist, for example, but I don’t think I’ve ever met another atheist who has a firm grasp on the Kalam Cosmological Argument (KCA). Widely believed to be among the most compelling arguments for theism, it goes like this:

  1. Everything which *began* to exist has a cause;
  2. the universe began to exist;
  3. therefore, the universe has a cause;

(After this point further arguments are marshalled to try and prove that a personal creator God is the most parsimonious causal mechanism)

Despite being clearly articulated in innumerable places, atheists like Michael Shermer are still saying “but if everything has a cause then what caused God?”

If you understand the KCA then the theistic reply is straightforward: “The universe began to exist, so it has a cause, but God is outside time and thus had no beginning.” The standard atheist line, in other words, is a complete non-sequitur. Atheistic rebuttals to other religious arguments don’t fare much better, which means a majority of atheists don’t have particularly good reasons for being atheists.

This has little bearing on whether or not atheism is true, of course. But it does suggest that atheism is growing because many perceive it to be what the sensible, cool people believe, not because they’ve spent multiple evenings grappling with William Lane Craig’s Time and Eternity.

Perhaps then we should keep this in mind as we go about building and spreading ideas. Let us define the ‘pebble form’ of a worldview as being like the small, smooth stone which is left after a boulder spends eons submerged in a river — it’s whatever remains once time and compression have worn away its edges and nuances. Let us further define a “Maximally Durable Worldview” as one with certain desirable properties:

  1. the central epistemic mechanisms has the slowest decay into faith-based acceptance;
  2. the worldview is the least damaging once it becomes a pebble form (i.e. doesn’t have strong injunctions to slaughter non-believers);
  3.  …?

There’s probably an interesting connection between:

  1. how quickly a worldview spreads;
  2. how quickly it collapses into a pebble form;
  3. the kinds of pebble forms likely to result from a given memeplex rotating through a given population;

Perhaps there are people doing research on these topics? If so I’d be interested in hearing about it.

Profundis: “Rapt”

Winifred Gallagher’s “Rapt” is a breezy, uplifting treatise on attention — that prism through which the light of experience is filtered, refracted, and bent. In an age that finds us buried 140 characters at a time, knowing how this vital process works is paramount for anyone seeking to live better by getting outside their own head. The science in Gallagher’s slim NYT-bestseller is elucidated with patient visual metaphors, and the prose is sprinkled with ample references from literature, science, history, and philosophy.

If you’ve been paying attention to the field of psychology then Gallagher’s insights into the relationship between attention and motivation, flow, visual perception, and the like won’t be particularly new. It’s nevertheless an entertaining and accessible treatment of the subject topics filled with all manner of interesting tangents.