In the real world, paralysis and stun are most often caused by issues with the nervous system, which is broken up into two main parts: The central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system, consisting of all the other nerves spread throughout the body. While both paralysis and stun are almost always nervous system issues there is a bit of a distinction I would make. Paralysis is a condition that means you are unable to move your body, or specific parts of it, while still being mentally intact, and (when it is caused by a malfunctioning nervous system) is usually an issue with the spinal cord and the peripheral nervous system and not necessarily an issue with the brain itself. Paralysis can, however, be caused by the muscles not working properly, if I am not mistaken. Stun on the other hand, though not often used as an actual medical term to my knowledge (most likely due to lack of specificity), is something primarily associated with the brain itself as opposed to any other body part (you would never say your arms or legs got stunned, for instance). The most common condition I would associate with "stun" is a concussion. A concussion is, of course, the result of a physically traumatized brain. Because of this I can easily see how stun is a completely brain/mental effect and would not be considered a movement hamper. Since "hold" in BG seems mostly synonymous with paralysis, and paralysis is being unable to move the body (due to either a physical or mental condition), I can easily see this being considered a movement hamper as well as a mental effect.
This reasoning appears to be reflected in the game too, as mind shields will often block both hold and stun, but freedom only blocks hold and more physical movement hampers such as web and grease (which are not blocked by mind shields). This appears to be the case in D&D in general, to my knowledge, as it is the same way in the other D&D game I have played (NWN).
There are three opcodes for the hold effect in BG2: 109, 175, and 185. Opcode 109 is seen in Web and Implosion. Opcode 175 is seen in Hold Person, Hold Monster, Death Gaze, and Paralyze. Opcode 185 is seen in Hold Undead and Otiluke's Resilient Sphere.
Presumably, 109 means a physical restraint, 175 is a mental effect, and 185 is reserved for other stuff. But Free Action prevents all three, which would suggest that 175 is NOT mental, since stun, which is clearly associated with Psionic Blast, a mental thing, bypasses vanilla Free Action. But Hold Person and Hold Monster are Enchantment spells, which are supposed to be involved in affecting the mind, not in the rest of the body.
I always wondered about the terminology behind "hold." Same goes for "turn" undead.
Magic, being magic, likes to deal directly with what science would call the symptoms of deeper problems. Stabbed by a sword? Here, let me un-stab you. No, I can't create blood, or fuse broken objects together. I don't ever need to address the actual structural changes caused by stabbing. I just un-stab people. The result is achieved without the underlying problem ever even being considered.
So it is with Free Action and all the various restraining effects. If something prevents you from moving, Free Action blocks it, with no regard for the method. I mean, in pnp it even prevents people from successfully grabbing you. That makes no physical sense, but magic doesn't care. It prevents you from moving, so Free Action stops it. Stun slips by because, technically, it's not (supposed to be) stopping you from moving. It's just making you so befuddled you can't move coherently.
And as to etymology, "hold" could either be used in the sense of "grip" or as in the archaic imperative form of "halt". I suspect the former, actually, although the later seems to fit better if the spell is mental. "Turn" I do know, or at least I've heard. Long ago, one method used by superstitious people (read: everyone) to prevent their dead from rising was to literally turn them to face downward in their graves. That way, if they animated and tried to claw their way out, they'd only dig deeper. How that got associated with D&D's "the power of Christ compels you" stuff, I do not know.
@Jarrakul: I have long been bothered by the sciency implications of magic. Natural healing is a ridiculously complex process that even modern scientists are still learning about. But a spellcaster in fiction can apparently repair every microscopic tear caused by a sword, just by using a spell that probably takes a few seconds to cast, even if they know nothing about microbiology or the healing process. In D&D, a cleric's healing is justified, since a god is mediating it and you can expect the god to be sort-of omniscient like that, but in most fantasy settings, there is no explanation for how a mage can do something so immensely complicated with such a simple process.
In my own fiction, I justify it in evolutionary terms: humans and other critters evolved in the midst of a magical world, so they evolved to incorporate tiny spells into their systems. You have a Golgi Apparatus; they have a Magi Apparatus, plus the Golgi Apparatus. This way, people's brains would already work along the right lines to get magic to work properly.
Same reason you can flip a coin: you might not understand all the mechanics behind your muscles, but you can still flip a coin, since your body is adapted fairly well to it.
Comments
In the real world, paralysis and stun are most often caused by issues with the nervous system, which is broken up into two main parts: The central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system, consisting of all the other nerves spread throughout the body. While both paralysis and stun are almost always nervous system issues there is a bit of a distinction I would make. Paralysis is a condition that means you are unable to move your body, or specific parts of it, while still being mentally intact, and (when it is caused by a malfunctioning nervous system) is usually an issue with the spinal cord and the peripheral nervous system and not necessarily an issue with the brain itself. Paralysis can, however, be caused by the muscles not working properly, if I am not mistaken. Stun on the other hand, though not often used as an actual medical term to my knowledge (most likely due to lack of specificity), is something primarily associated with the brain itself as opposed to any other body part (you would never say your arms or legs got stunned, for instance). The most common condition I would associate with "stun" is a concussion. A concussion is, of course, the result of a physically traumatized brain. Because of this I can easily see how stun is a completely brain/mental effect and would not be considered a movement hamper. Since "hold" in BG seems mostly synonymous with paralysis, and paralysis is being unable to move the body (due to either a physical or mental condition), I can easily see this being considered a movement hamper as well as a mental effect.
This reasoning appears to be reflected in the game too, as mind shields will often block both hold and stun, but freedom only blocks hold and more physical movement hampers such as web and grease (which are not blocked by mind shields). This appears to be the case in D&D in general, to my knowledge, as it is the same way in the other D&D game I have played (NWN).
Presumably, 109 means a physical restraint, 175 is a mental effect, and 185 is reserved for other stuff. But Free Action prevents all three, which would suggest that 175 is NOT mental, since stun, which is clearly associated with Psionic Blast, a mental thing, bypasses vanilla Free Action. But Hold Person and Hold Monster are Enchantment spells, which are supposed to be involved in affecting the mind, not in the rest of the body.
I always wondered about the terminology behind "hold." Same goes for "turn" undead.
So it is with Free Action and all the various restraining effects. If something prevents you from moving, Free Action blocks it, with no regard for the method. I mean, in pnp it even prevents people from successfully grabbing you. That makes no physical sense, but magic doesn't care. It prevents you from moving, so Free Action stops it. Stun slips by because, technically, it's not (supposed to be) stopping you from moving. It's just making you so befuddled you can't move coherently.
And as to etymology, "hold" could either be used in the sense of "grip" or as in the archaic imperative form of "halt". I suspect the former, actually, although the later seems to fit better if the spell is mental. "Turn" I do know, or at least I've heard. Long ago, one method used by superstitious people (read: everyone) to prevent their dead from rising was to literally turn them to face downward in their graves. That way, if they animated and tried to claw their way out, they'd only dig deeper. How that got associated with D&D's "the power of Christ compels you" stuff, I do not know.
In my own fiction, I justify it in evolutionary terms: humans and other critters evolved in the midst of a magical world, so they evolved to incorporate tiny spells into their systems. You have a Golgi Apparatus; they have a Magi Apparatus, plus the Golgi Apparatus. This way, people's brains would already work along the right lines to get magic to work properly.
Same reason you can flip a coin: you might not understand all the mechanics behind your muscles, but you can still flip a coin, since your body is adapted fairly well to it.