I'm working on a moddified D&D Pathfinder game and I want to strip out the old way of doing magic and add a Sympathetic system. I read a build for sympathy magic in a 3.x 3rd party book (I wana say it was Occult lore but can't remember) and it seemed very workable, though having just come off reading 'The Name of the Wind' I'm wondering if I can't build something that was more pseudo-science like.

On the one hand, I like the more realistic approach of shifting and transmuting energy to change the physical world, on the other being, that technical could lead to many a mid game disagreements, plus it would not translate well to complex or abstract tasks (healing, changing luck, mind control). I worry though, that If I simply make sympathy  a catch all magic class and allow people to select different types of sympathy like you can with cleric domains, I'm just going to put a thin vainer over the existing spell list, or have some pathways be much more useful than others.

I've also thought about making a few other branches magic that all work on vaguely sympathetic principles, but are more suited to different types of tasks and vary in their execution.  A current notion is to break up magical tasks into the very finite and physical with a more scientific sympathy, have more enviromental and abstract magics be covered by another discipline.

hmm need to get to work so will think more later

You might want to establish more clearly what you mean by sympathetic magic as will help poster's zero in on what you're looking for.  In fact, it might be a good idea to write this out as "laws of magic" for the setting.  Not only will that help us, but it also can give you a nice flavor piece and guideline while also being very fitting to a more scientifically oriented magic system.

My best guess right now is you mean magic where "like affects like" is a major principle.  In that case, I'd say you're looking to emphasize metaphysical links between similar or related items.  I'd make a significant part of the system being able to invoke these links, with items that have a strong association to the target having greater link strength.  These links would serve two purposes.

First, they act as a reference to the target, much like how pointers work in programming or how an address let's you know where to find someone.  This lets sympathetic magic work on targets who may not even be present.  That factor alone can be a significant advantage and a scary one for your average citizen.  I'd say the strong the link is, the more likely the spell is to be delivered to the right "address" and find it's target.  This may also work to grant increased accuracy while the target is present, though doing so is often far more risky as it's difficult to defend oneself while staging these kind of symbolic actions.

Second, the act of physically acting out what you want to happen can be a very effective way to focus the caster's will and intent.  I'd say treat this aspect as a ritual magic approach which builds up power over time.

You may have noticed this has a definite feel of "do big rituals far away from the enemy".  While very in keeping with most magic traditions though out history, you might be looking to use magic in combat.  In that case, the following variants might work:
- Pre-Battle Buffs: This is probably the closest to traditional war magic.  By doing things like making symbolic arrow bounce off a representation of the target you might grant them protection from actual arrows, and so on.  If you've a model of target, you might doing a quick version mid battle.
- Invoked Properties: This would consist of transfering the properties of an object to another or making the object act like something else with similar properties.  For example, you might touch a stone to a warrior and invoke it to increase the warrior's toughness.  Similarly, you might invoke the "heat" of something like chili powder to make it burn like fire.
- Battlefield Performances: By symbolically breaking a model of the enemy you can help make that happen.  While this might have less magical oomph than a prolonged ritual, it does have a nice morale lowering effect.
- Invoked Preparations: You could use a short ritual to trigger power that had been built up previously.  To do this, you'd want some of the tools used in the original ritual.  This takes more fore thought, but combines speed and power nicely.

I find odd that you single out thing like "healing, changing luck, mind control" as poor matches to sympathetic magic.  Those are exactly the kind of areas existing magic traditions have focused on.  For example, you can sympathetically heal wounds by making a clay sculpture of the wound then shaping it away.  You can also purge disease by using something to represent the disease, then ritually burning or casting out the item.  Changing luck and mind control are both simple matters of symbolically acting out what you want to happen and relying on the magic to make events mirror what you acted out.

If you're interested in magical laws, you might also want to look up some stuff by Isaac Bonewits.

I singled out those tasks as being difficult in relation to setting up a sympathetic system similar to that present in The Name of the Wind. In that story Sympathy followed three core rules. 1) Like effects Like 2) Part of a thing can stand for the Whole of a thing and 3)Energy can neither be created nor destroyed.
The examples present in the book are purely physical, with different bonds effecting different physical properties. When the main character first learns Sympathy, it is illistrated to him by another character moving one coin by forming a bond to another coin then picking it up. The result is that both coins would move in space and equal amount and the Sympathist would exert a physical effort equal to lifting the weight of both coins. The likeness of the objects would alter the effcientcy of the bond, so the Sympathist can bond anything together but may not be able to do much do to poor efficeincy of the bond. When the main character plays around with the first bond he learned he found that lifting a branch with a twig he broke off was easy and the total weight was equal to the branch + twig. When he tried to bind two unlike things the weight was over double what the combined weight of the items should be.
The actions become more complex as he learns to hold different bonds simultaneously. A later example envolves him trying to break a large glass barrel that is hard to reach and very stoutly built. He makes what I assume to be a dual bond, the first links his body to a small piece of glass in his hand via his blood being on it, the second links the glass in hand to the barrel. He then drops the glass and steps on it, using heat energy pulled from his body to add to the force he applies to the barrel through the glass bond. The result being he shatters a barrel that would otherwise need a pickaxe to punch a whole in.

The book has many more examples, and I think i should re read the text to get a better feel for the logic of it, but all the things that happen are direct cause and effect. There is little to no symbolism to the magic (I think at one point a doll was used to illustrate bonding efficiency and it also happened to demonstrate targeting) but no abstract tasks are covered or very complex and precise tasks such as medical work. There was an intersting glimpse at ruins being used in the world to effectively maintain a sympathetic link without actually needing anyone to think about it, thus 'magic' items are created.

As for my game, I like the pseudo-science approach, giving players a set of tools and letting them get clever with the application. It also lends its self to fast play as bonds and actions happen as fast as the player can think and physicaly do. It also opens the doors to MANY questions just on the clear cut physics bonds. There is mention of chemical bonds that they never go into and I can only assume there is some limit to what you can and cannot bond, or it would seem that anything would be possible just by bonding the Sun as a power source, then let the good times roll.
Using a more thematic form of Sympathy would probably be much easier to manage, since then it could be boiled down to 'I do something which mimes out my desired effect' with a plus or minus based on what props are used and how closely it falls in line to what a character is suppose to be good at.

Just as a quick thought, while he doesn't focus quite as much on 'sympathetic effects', Larry Niven in his "The Magic Goes Away" stories (or "The Warlock" stories) presents magic in a kind of pseudo-scientific way. Plus they're darn good reads :) His stories are where Richard Garfield got the idea of mana drawn from the land to power spells for Magic: the Gathering, by the way.

I've put some more thought into how Sympathy would work and now have more questions than answers. I'm going the route of a scientific set of bonds that can be mixed and matched to form various effects that roughly adhere to the laws Newtonian physics and thermodynamics.

I'm starting off with the first example from The Name of the Wind, where two coins are joined and moved equally through spaced. I have many more questions than answers.
1) The coin in hand is said to feel as though it weighed twice as much as it did before the bond. This implies that the effects of gravity on the bonded coin (aka the Target) is transfered to that of the coin in hand (aka the Focus).
2) While spacial movement in relation to the character is described (moving the coin up and down and side to side) the geometry of the coin is not described. Does twisting the Focus cause the Target to pivot on it's access? If so how is the axis of Focus and Target defined?
3) If the effects of gravity are felt through the Focus from the target, are other forces transfered as well? I do not recall the character trying to press the coin through the table, but I can assume that one of two things happened
  a. The force of the table pressing against the Target is transmitted in full to the Focus, resulting in the Focus NOT moving
  b. The force of the table pressing against the Target is not transmitted fully to the Focus, resulting in the Focus moving but with a certain amount of resistance.
I'm inclined to believe 'b.' is true as the ability to make floating platfroms would be all to easy by linking an object held aloft to one on a solid base like the ground. This was present no where in the book, but for my own game world I could declare it either way.

Allowing scenario 'a' would make for some very strait forward and effective uses for even simple sympathy. Imagen having two sticks and binding them to the closest visible tree (or any tree that could be thought off for that matter). The character could effectively climb thin air by pulling themselves over hand, the force of their weight pulling down going straight into a stout tree which is more than capable of bearing it.

Thoughts?

HM,
  Well, I think the system that works best for more flexible and less rigid systems such as this are ones where you define the trait and give it a mechanical rating. And then the rating is used, regardless of the descriptor for that trait. So, if I make Gatling Gun (1d4) and I go up against someone with crossbow (1d12), then I am at a disadvantage, even though the descriptions would say otherwise.
  Dogs in the Vineyard and HQ1 do this extremely well. you can get a really subtle and nuanced game play and characters, without haggling over mechanical values. Because the value assigned is in essence the rating of how much influence that Trait has over the shared imaginary world the gaming group is creating together.
  If you don't know much about these games, let me know and I can elaborate. I hope that helps.

I've read the Dogs in the Vineyard rule book and understand your meaning of assigning values to different important aspects of the story despite their description. I don't believe this style mechanics would work for my situation since sympathy is suppose to be very direct cause and effect relationship. I'm really trying to build a logical, numberless set of tools that will force myself and players to brush up on their physics if they want to apply it effectivly.

I'm looking at it like a series of logic problems on how bonded items would interact so that the various forces on them equaled out. To start I'm looking at spatial relation and motion. My current model for the simplest form of bond is that of a 'single link' in which the Focus acts as a sender and the Target a receiver. In this model forces acted upon the Focus are transmitted to the Target, but not vice versa.
Heres an example to illustrate-

Two identical blocks of mass X are on a smooth frictionless surface. A single link spacial bond is placed on block A connecting it to block B, the items being so similar that 100% effeceincy is reached. When force N is applied to block A it accelerates the blocks a delta(v)=(2X)/N
Both blocks would have the same velocity and spacial displacement at any point in time.

If an object obstructed the path way of block B (the target block) block B would experiance two vectors of force. The first force would equal 1/2 N which is the original force, the second would be 1/2 N which is the force exerted on the block from it's obstruction.
Block A would continue accelerating and traveling  in the vector of the original force, while block B would be brought to a stand still.

So far, I'm happy with this, but things get harder for me to wrap my brain around when you throw gravity in the mix. Logically the ground both blocks are sitting on exerts a force equal to 2Xg where 'g' is the acceleration do to gravity. When the blocks are bonded, half of all forces exerted on block A are transmitted to block B, making A feel as though it had the mass of 2X. Since the forces acting on block B make no difference to the forces acting on block A, the ground would exert a total of 3xg force, 2Xg for block A and Xg for block B. Since block B is already being supported, it would accelerate upwards with a force equal to Xg. Once B is no longer in contact with the ground, the forces equallize. B is being held at exactly ground level, but not exerting force on the ground since it is being held up by the force from block A. That would effectively make block B weightless and any external forces acting upon it would be so as though it was in zero-g. That is not how I want spacial sympathy to work.

If I define the bond as a two way street between the linked objects, I can by pass this issue. The blocks would then act as though joined by an invisible steel bar, transmitting  force back and forth. In the first example given, block A would come to a stop when block B was obstructed as  the forces on B would be transmitted to A. This how ever opens up a whole can of worms, as well as making sympathy more effective in certain situations when bonding dissimilar items than similar. Being able to climb mid air as I mentioned in an earlier post would be a prime example.

horomancer wrote:
I don't believe this style mechanics would work for my situation since sympathy is suppose to be very direct cause and effect relationship. I'm really trying to build a logical, numberless set of tools that will force myself and players to brush up on their physics if they want to apply it effectivly.

My meaning to sympathy being 'numberless' is the spells don't have any number associated with them aside from a mechanic to illustrate an inefficient bond. If you link two objects and try to move them, you would make something like an 'athletics' check or STR check as normal. The bonds should not give a direct mechanical advantage, rather allow of greater flexibility on how a problem could potentially be solved.
It seems the only solution is a statement that only conscious force is transmitted. I don't like that since it's really just an omission I can't make the energies even out.

Hmmmm. maybe if i define the potential energy between bound items to be >= 0, I could then declare that any motion within the vector of gravity to be un-transmittable beyond a plane set by the spacial location of the Focus at the time of binding. So if I hold an object in my hand and bind it to an object to the ground, the potential energy of my Focus is equal to mgh and the Target is 0. Since the bond cannot transmit negative potential energy lowering the Focus towards the ground results in no effect to the Target, and the observer only feels the weight of the Focus, not the total weight of Focus and Target. Trying to raise the Focus after lowering it would impart a gain to potential energy which DOES transmit through the bond causing both Focus and Target to rise in the air. The effects would be like the two items tied together by a tape measurer, moving towards the bonded item in respect to gravity gets you nothing, moving away from or perpendicular too results in the transmission of energy. This makes the logical paradox for spontaneous generation of weight go away, but what can of worms have i opened?
What happens when the potential energy of the Target item changes?  Say I lift a penny off the table and set it on the ground?

My head is hurting again. Maybe I should just accept defeat and say that once an item is bonded the Focus transmits energy that would displace it from it's current position and gravity doesn't count. Then set in an artificial cap on the amount of energy transmittable linked to a characters CHA bonus to keep from having floating platforms bearing absurd amounts of weight.

Another problem with the system as described. (Utilising it in a very literal physics sense)

Object A & B are n units apart from each other and bonded, like a dumbell.  A is the "focus" in my hand, B is the "target" I bonded.

If I hold A and rotate it so that the bond is NOT parallel to the direction of turning, will B rotate on the spot or will it pinwheel like a ferris wheel?

I think you're going to have some issues.  Somewhere you need to end up developing a connection between the efficiency of the Bond and the Difficulty of the Skill DC.  For example, 90+% bond = 0, 80-90% = -1 on roll, etc, etc.
That seems to be something you need to develop.

I had side stepped that problem by spell selection. You could make the target rotate on it's axis or you could make it pivot around the focus depending on which spell you used.
I haven't given thought to this for a while since it gave me to many headaches when I tried to make the math make a modicum of sense. I haven't shelved the notion yet, but I may have to go with a much more general, theatrical notion of sympathy magic as opposed to a hard science one. That or just kinda break it down into what the result the character wants, how much energy it would take, and how much energy that scrounge up from what ever is at hand.