Ars Magica and Metaphysics

Irritatus of Bonisagus creates a box of twelve pieces of wood fixed together with nails.

He removes a splinter from the box, and fixes it as an Arcane Connection to the box.

He casts a spell to detect the box. It works.

He replaces one of the pieces of wood, saving the piece of wood he removed. He casts the spell again.

What happens?

He repeats the procedure eleven further times.

What happens when he casts the spell after each replacement?

He takes the twelve pieces of wood he saved and assembles them into a box.

Which box does his spell detect?

This is, as many people will have noticed, a simplified version of the Ship of Theseus. Philosophers have been arguing over the right answers to the questions above (phrased as "when does it stop being the same ship?") for thousands of years, and have yet to reach an agreement.

Because Hermetic magic is built around Aristotelian metaphysics, it is capable of providing a decisive empirical answer to this question. (It stops being the same box, or ship, when the AC stops working.)

This sort of issue is why there are areas of Hermetic magic where I choose to be vague. What is the boundary of an Individual? Is a suit of armour an Individual or a Group? What is the precise line for something to be inside a Structure? This is a game. If I could solve philosophical problems that have stumped everyone for millennia — actually, I'd probably still make more money managing Ars Magica.


I really like this post. That being said, whether you decide to answer philosophical problems or not, I believe you could still make more money managing Ars Magicka if Atlas decided to continue developping the franchise. It's worth repeating from time to time. :slight_smile:


In this case, the splinter comes from one of the 12 pieces, the real box has that piece.

For the general case, Irritatus will find the answer through his experiments. We won't though. :melting_face:


Nice post.

I think there's a point when Edgecasius of Pendantria can sort it out with his troupe, and not expect the rule book to be written like a legal text or programming language to make it crystal clear.

Then again, I don't know if the range of my personal thoughts can be extended to a group target. Can someone point me to a page in the rule book or errata to be sure? :slight_smile:



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A few years back I made a post about the near-infinite divisibility and aggregation of the elemental Forms. A patch of sand is millions of individual grains, but can be manipulated with Individual or Part magic rather than Group. Same with water, air and fire - you can split them apart or clump them together without limit, and Individual often still applies. Hermetic magic is fuzzy at the edges, that's why it's called Arts rather than Sciences.

The box would probably never lose the AC. Why? Because the AC was created to THE BOX, not to the components of the box. If you have an AC to a hill, if someone removes a clump of dirt from the hill and goes elsewhere, that AC doesn't apply to the clump of dirt. If someone moves a random clump of dirt onto the hill, the AC will affect the introduced dirt as it quickly becomes part of the hill.

We see this kind of division/aggregation regularly in the elemental forms, and it can work on even living things. Should you chop the arm off a grog, your AC to that grog doesn't really apply to the arm anymore. Regrow his arm and the AC can affect the new arm, as it is part of the grog. Now, you could use the grog as an AC to his former arm (and vice versa), but IMO Arcane Connections are defined through use - they are either used or fixed for a specific purpose when they are used or fixed.

For example, the splinter from the box could be an AC to the tree it came from, the person who made the box, or the box itself. This probably doesn't have to be defined until it is used for some magical purpose (casting of a spell or use of a Supernatural Ability). As time passes (unless fixed), the potential uses of the AC will diminish as the AC fades. If the AC is fixed, the storyguide should ensure what it is being fixed to is defined (the box, in this case). So long as the box doesn't cease to exist, the AC persists. Note that with Hermetic magic this could mean you could PeHe the box out of existence entirely, but CrHe magic with the AC could conceivably re-create the box entirely, because as far as magic is concerned, if something existed in the past, it can be re-created (unless it has a soul, hermetic limits still apply). And it will still be the same box as far as the AC is concerned.

The question is what iteration of the box would you get if you re-created it. Since an AC is an ongoing effect once fixed, I imagine the AC metaphysically always knows the current state of the box, but I can see an argument for re-creating the box in the state when the AC was fixed.

Also, if you chopped a grog perfectly in half, which half would the AC apply to? Probably irrelevant, as it's not actually possible (one half will always be greater, even if it's effectively impossible to measure), but we'd have to assume it's the part the spirit/soul stuck to in the brief instant before death.


Keep in mind that for the AM universe the answer could well be different tomorrow than it is today because teh universe is, by cannon, ruled by a sentient being (God, the SG, take your pick) who might well decide they like being somewhat perverse in annoying the kinds of people who try to find definitive answers to these sorts of questions, where the real answer is "WHATEVER I FEEL LIKE DOING TODAY MORTAL!"


As long as it's better than double fanucci...

There are multiple metaphysical elements at play here.

The original box is composed of the twelve pieces of wood yet has a distinct identity as the whole that is not contained or conferred on the individual pieces. (Some philosophers would argue this point, but I don't believe Aristotle would.) This means removing individual pieces and replacing them does not change the identity of the box, though it does mean that it is no longer perfectly equivalent to the old version of itself (has changed in state/form).

One answer (among many) to the general Ship of Theseus question is that this concept of composition is the crux of assigning identity to the complex object that is the ship (box). Removing and replacing pieces doesn't change the continuous identity of the box any more than the continuous identity of a person changes as they grow from a young child to a very non-equivalent adult person. The entity being referenced is still the same, bearing the same identity, even if it is no longer perfectly equivalent.

When we take the removed pieces and assemble them into a box again, while the previous box still exists, then arguably we have composed now a new box that came into being at a later time and has a distinct identity.

Magic complicates this with the concept of Sympathy and Arcane Connections.

I would personally ascribe Sympathy, and thus the thing "connected to" by an Arcane Connection, to the complex Whole entity/object, and not to any of the things that compose that Whole. Unless the real intent was to try and target a specific Part. The overall Sympathic identity, the Whole composed by Parts, remains the same until or unless something decisive is done to attempt to change this.

By which I mean something like a mystical renaming ceremony that seeks to fundamentally change the identity of the Whole, while severing identity ties to the past.

An interesting question!


Sad but only too true.


It's essentially the same as the idea of karma and the soul in Buddhism- you are not a soul which is an unchanging thing the same way a candle flame is not a object, but something whose composition is constantly changing yet maintains a stable pattern that is identified as an individual. Similarly the ship of Theseus appears constant as it's parts are swapped in and out. similarly no portion of my body at a molecular level is the same as what it was when I was two. Neither am I the same person in ters of behaviors and beliefs as when I was two, and yet the pattern of my being can be drawn continuously through time from that point to the current day.
But like I said, that is Buddhism, which is definitely not the same thing as Ars Magica, where reality is ultimately the whim of God/the SG.

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In brief thought, I would say it ceases to be a connection to the box when it is split up enough to no longer be called a box Essentially.
That is a simplified answer tho. An all at once change.

This is a land of philosophy and maybes.
Maybe the AC is always pointing to that box, if it always stays a box, even if it has no original components. Possibly because it is a fixed arcane connection.
Maybe a nonfixed connection would re-adjust to point to the box piece it was splintered from, maybe not.
Maybe once 51% of the boc was new, the connection would fail.

Addendum: in your particular example, there is always only one box, which does make the question a little easier.

Consider a candle flame
If I use MuIg(Te) to change it into a gem, then cut a piece off of that gem and fix it as an arcane connection. I put the AC in a box enchanted to keep it as a stone, and replace the rest of the flame on a candle.
The gasses from the wax that make up the flame, that are constantly burning do not remain the same from second to second, yet the flame is considered the same flame.