Fire spells don't obey the laws of physics

[HoodedHero007]

disregarding the whole "magic" part, anyway.
let's take Fire Bolt, a cantrip that, among other things, sets fire to things that aren't being worn or carried.
Let's say Mr. Wizard hurls it at a block of unobtainium, which has a specific heat of 1 trillion joules/ degrees celsius and a burning point of 900 googolplexianth degrees celsius, since it is not being worn or carried, it's set on fire, therefore, the bolt is hot enough to do that, which in most cases, is enough to melt anyone's face of within a 100 mile radius (or something like that)

[raygun goth]

It sets fire to "flammable" things.

The real question here is why it doesn't create a cool, gentle breeze across your back when you hurl it away from you.

[smcmike]

You are using an awfully open interpretation of "flammable." Most DMs would interpret it differently, I think.

Also, of course magic doesn't follow the rules of physics.

[JoeJ]

Why is surprising that a magic spell doesn't follow real world physics?

[Regitnui]

There was a section in a Dresden Files book about how "Arcanos" fire spells don't work like reality. And this is coming from a wizard who's known for setting buildings on fire. If anyone knows how real magic fire works, it's Harry "the building was on fire and it wasn't my fault" Dresden.

[krugaan]

Fire spells don't obey the laws of physics...

well...


disregarding the whole "magic" part, anyway.

Ok.

OP has forgotten that firebolt only sets to flammable things.

[uraniumrooster]

Wait, you guys are telling me D&D mechanics aren't based on real science?

Well... that explains my high school physics grades I guess.

[Shaofoo]

PSA: This is yet another "How to break the game with a cantrip by throwing "science" with a magic hand till you choke on it... on the magic hand, not the science" topic. Do not take this too seriously or at all.

But really shows how lazy OP is, why not burn the air since air is an unattended object and since all the air is burnt you will cause an extinction level event. (Do not take this seriously, it is to show how lazy and pointless this entire exercise is).

[Shining Wrath]

The firebolt only ignites the flammable. Flammable is in the DM's purview.
Perhaps the unobtanium ignites and burns - one atom at a time. It requires 6.02*10**23 rounds to burn a mole of unobtainium, but it does burn.

Really, though, the correct answer is "science has no place in a world with wizards" and leave it there.

[Theodoxus]

Well, technically, everything is flammable, eventually.

[krugaan]

Well, technically, everything is flammable, eventually.

Doesn't flammable generally mean the heat of it's own combustion is enough to continue the reaction? That doesn't apply to a lot of things.

edit: so while things can be altered by fire, they won't necessarily be set on fire.

[Shining Wrath]

Well, technically, everything is flammable, eventually.

Define "flammable". Some things sublimate into gas without ever combining with atmospheric oxygen.

[JoeJ]

Nowhere in the spell description does it say that the burning material is incapable of doing any damage on its own. So the unobtainium ignited by the Fire Bolt would presumably act just like burning unobtainium normally does.

[Shaofoo]

Well, technically, everything is flammable, eventually.

The way he presents it he basically says that "on fire = instantly convert matter into energy" the way he presented his case. You can chuck a Fire Bolt at water, asbestos or even fire itself and it will burn because it says so and transform all matter into energy because there is no comprehension at all and the point is to break the game by misunderstanding science.

[krugaan]

The way he presents it he basically says that flammable = instantly convert matter into energy the way he presented his case. You can chuck a Fire Bolt at water, asbestos or even fire itself and it will burn because it says so and transform all matter into energy because there is no comprehension at all.

I had a good lol at that one.

[Anonymouswizard]

OP has forgotten that firebolt only sets to flammable things.

Actually, flammable is a very bad term to use, as most things will go up in flames with enough heat applied quickly enough (no values because this is not my field).

It's obvious what flammable is meant to mean, but until the designers define inflammable this is a legitimate way to break the game, if you're willing to receive a book upside the head.


Really, though, the correct answer is "science has no place in a world with wizards" and leave it there.

This is wrong on so many levels. While rules should not be interpreted overly strictly (which leads to either the commoner railgun or the commoner teleporter) a world with magic should still have the scientific method, if a different body of scientific knowledge.

[Shaofoo]

This is wrong on so many levels. While rules should not be interpreted overly strictly (which leads to either the commoner railgun or the commoner teleporter) a world with magic should still have the scientific method, if a different body of scientific knowledge.

Better said, fantasy world should stick with fantasy rules and real world should stick with real rules. Do not mix one with the other because what you can do in real life does not have a bearing what you can do in fantasy life and vice versa. Something that reacts a certain way in the real world could react a different way or even be inert in the fantasy world.

[krugaan]

Actually, flammable is a very bad term to use, as most things will go up in flames with enough heat applied quickly enough (no values because this is not my field).


again ... heat changes things, but only certain materials will have a self-sustaining exothermic (releasing energy) reaction that "flammable" requires. If remove the source of the heat (ie the firebolt) the reaction continues ... that's flammable.

[Ace Jackson]

Better said, fantasy world should stick with fantasy rules and real world should stick with real rules. Do not mix one with the other because what you can do in real life does not have a bearing what you can do in fantasy life and vice versa. Something that reacts a certain way in the real world could react a different way or even be inert in the fantasy world.

At the same time, if there is no grounding, no points of reference, there can be no meaningful interaction with the system, no use in playing if my character walks out the door and immediately flies into the sun for no player-perceptible reason.

My take on these kinds of issues is to say that true simulation is impossible, you can talk to me as the GM about why something might be cool, but I reserve veto power for when it simply no longer makes sense.

Yes, titanium burns before it melts in the presence of oxygen, no, you cannot set the metal siege engine on fire with firebolt. Why? Because of two reasons, one, I am the GM, two, when they wrote the description of firebolt, they wrote it such that you wouldn't need a doctorate to play the game. Look at it like you're a young middle to highschool student, unless explicitly declared otherwise during the planning of the campaign, and we will all be fine. If you want to play a game engine built such that you need a doctorate to meaningfully understand how to play, fine, but I'm not running it.

EDIT: Typo

[Anonymouswizard]

Better said, fantasy world should stick with fantasy rules and real world should stick with real rules. Do not mix one with the other because what you can do in real life does not have a bearing what you can do in fantasy life and vice versa. Something that reacts a certain way in the real world could react a different way or even be inert in the fantasy world.

Exce the general of fantasy is 'like reality unless otherwise noted'. While I'll agree that magic doesn't have to strictly follow the laws of physics, getting rid of gravity because 'it's fantasy' is just silly.

[Shaofoo]

Exce the general of fantasy is 'like reality unless otherwise noted'. While I'll agree that magic doesn't have to strictly follow the laws of physics, getting rid of gravity because 'it's fantasy' is just silly.

Unless the world where the game takes place is without gravity (Isn't the Plane of Air like this where you could choose where to fall?). I do agree that some things should be assumed but not all. Of course this comes back to good will and not trying to be a munchkin and one shot the campaign by trying to misunderstand how does setting things on fire work.


At the same time, if there is no grounding, no points of reference, there can be no meaningful interaction with the system, no use in playing if my character walks out the door and immediately flies into the sun for no player-perceptible reason.

My take on these kinds of issues is to say that true simulation is impossible, you can talk to me as the GM about why something might be cool, but I reserve veto power for when it simply no longer makes sense.

Yes, titanium burns before it melts in the presence of oxygen, no, you cannot set the metal siege engine on fire with firebolt. Why? Because of two reasons, one, I am the GM, two, when they wrote the description of firebolt, they wrote it such that you wouldn't need a doctorate to play the game. Look at it like you're a young middle to highschool student, unless explicitly declared otherwise during the planning of the campaign, and we will all be fine. If you want to play a game engine built such that you need a doctorate to meaningfully understand how to play, fine, but I'm not running it.

EDIT: Typo

The rules provide grounding, go by what the rules say if you need a point of reference. Also the DM provides the grounding point as well.

Like I said, the OP has done this kind of shenanigans before, he isn't trying to be a simulationist, he is trying to break the game by using bad logic. The end result isn't trying to be as close to real life but to deal all the damage.

[pwykersotz]

again ... heat changes things, but only certain materials will have a self-sustaining exothermic (releasing energy) reaction that "flammable" requires. If remove the source of the heat (ie the firebolt) the reaction continues ... that's flammable.

^^Pretty much this.

[smcmike]

This is wrong on so many levels. While rules should not be interpreted overly strictly (which leads to either the commoner railgun or the commoner teleporter) a world with magic should still have the scientific method, if a different body of scientific knowledge.

I respectfully disagree. If your character wants to sit around doing science experiments, he can do it in someone else's game. In my game, the world basically simulates perceived reality, with a healthy dose of genre ridiculousness.

[Anonymouswizard]

I respectfully disagree. If your character wants to sit around doing science experiments, he can do it in someone else's game. In my game, the world basically simulates perceived reality, with a healthy dose of genre ridiculousness.

And a character should be able to study that and exploit it, whether it's the wizard developing buff spells, the Taoist priest mixing martial arts and magic, or the scientist building an antimagic field generator.

Although I am someone who wants to play Academia: the RPG, which was released under the name 'Ars Magic'.

EDIT: also, I've previously managed to annoy GMs when my scientists manage to sit down and science, because I will detail my experiments and try to exploit the findings.

[krugaan]

Like I said, the OP has done this kind of shenanigans before, he isn't trying to be a simulationist, he is trying to break the game by using bad logic. The end result isn't trying to be as close to real life but to deal all the damage.

It's much more satisfying to beat them at their own game.

[Ace Jackson]

Unless the world where the game takes place is without gravity (Isn't the Plane of Air like this where you could choose where to fall?). I do agree that some things should be assumed but not all. Of course this comes back to good will and not trying to be a munchkin and one shot the campaign by trying to misunderstand how does setting things on fire work.



The rules provide grounding, go by what the rules say if you need a point of reference. Also the DM provides the grounding point as well.

Like I said, the OP has done this kind of shenanigans before, he isn't trying to be a simulationist, he is trying to break the game by using bad logic. The end result isn't trying to be as close to real life but to deal all the damage.

Alright, I can better understand what you're saying and why you're saying it now. Much appreciated.

[comk59]

*reads thread title*

... Well, yeah.

[smcmike]

And a character should be able to study that and exploit it, whether it's the wizard developing buff spells, the Taoist priest mixing martial arts and magic, or the scientist building an antimagic field generator.

Although I am someone who wants to play Academia: the RPG, which was released under the name 'Ars Magic'.

EDIT: also, I've previously managed to annoy GMs when my scientists manage to sit down and science, because I will detail my experiments and try to exploit the findings.

Right, that's what I mean. Get that stuff outta there. You wanna research spells, you use the rules on researching spells, or you just talk it over and suggest some effects that you'd like to see.

There really isn't a reason to think the scientific method is easily applicable to magic, and trying to apply it requires creating a magic system far more detailed than what is provided by the game.

[Anonymouswizard]

Right, that's what I mean. Get that stuff outta there. You wanna research spells, you use the rules on researching spells, or you just talk it over and suggest some effects that you'd like to see.

There really isn't a reason to think the scientific method is easily applicable to magic, and trying to apply it requires creating a magic system far more detailed than what is provided by the game.

Except for the fact that magic is easily repeatable. Get 500 fire spells, cast them all a half dozen times and you can start working out what makes them differ. It might be impossible to deduce the entirity of the rules in one lifetime, but you can work stuff out.

Now if you want to have magic where the scientific method isn't valid you can have it, but it makes wizards frustrating to play.

Excuuuuse me princess for wanting realism.

P.S. why can't I have my learned Taoist using magic alongside his kung fu?

[smcmike]

Except for the fact that magic is easily repeatable. Get 500 fire spells, cast them all a half dozen times and you can start working out what makes them differ. It might be impossible to deduce the entirity of the rules in one lifetime, but you can work stuff out.

Now if you want to have magic where the scientific method isn't valid you can have it, but it makes wizards frustrating to play.

Excuuuuse me princess for wanting realism.

P.S. why can't I have my learned Taoist using magic alongside his kung fu?

I don't understand the postscript - what is that referring to?

My point is simply that, even if there are a set of "rules of magic" that are possible for a human to comprehend, you are asking the DM to create these rules from whole cloth, when he'd probably rather just be running a fun adventure.

"My character finds 500 slight variations on Fireball, and spends 8 years studying them to determine how they work."

"Ok."

"And?"

"And what?"

[krugaan]

Except for the fact that magic is easily repeatable. Get 500 fire spells, cast them all a half dozen times and you can start working out what makes them differ. It might be impossible to deduce the entirity of the rules in one lifetime, but you can work stuff out.

Yes... after 500 fireballs you deduce that it does 8d6 fire damage over a 20' radius. Oh, and you can cast the epicenter about 120' away from your person. And some other little details.


Now if you want to have magic where the scientific method isn't valid you can have it, but it makes wizards frustrating to play.

Excuuuuse me princess for wanting realism.


...I've previously managed to annoy GMs ...

Generally people try not to annoy other people.


P.S. why can't I have my learned Taoist using magic alongside his kung fu?

Taoism isn't really a thing in DnD. I mean, unless your DM allows it, but that's always the caveat to everything.

[JackPhoenix]

I don't understand the postscript - what is that referring to?

My point is simply that, even if there are a set of "rules of magic" that are possible for a human to comprehend, you are asking the DM to create these rules from whole cloth, when he'd probably rather just be running a fun adventure.

"My character finds 500 slight variations on Fireball, and spends 8 years studying them to determine how they work."

"Ok."

"And?"

"And what?"

"All right. Meanwhile, rest of the party will follow the plot and actually play the campaign. You can roll up a new character, or wait until the others get through those 8 years of ingame time to catch up with you."

[smcmike]

"All right. Meanwhile, rest of the party will follow the plot and actually play the campaign. You can roll up a new character, or wait until the others get through those 8 years of ingame time.

As a more friendly DM might do it, though -

P: "I do X experiment, (lists out steps)"

DM: "What are you trying to accomplish?"

P: "My character is trying to scientifically test the nature of magic."

DM: "Oh, ok. What does he find out?"

[Anonymouswizard]

Yes... after 500 fireballs you deduce that it does 8d6 fire damage over a 20' radius. Oh, and you can cast the epicenter about 120' away from your person. And some other little details.

What about Fire Bolt, Burning Hands, Hellish Rebuke, Flaming Sphere, and all those ones I've forgotten that are in the PhB.

I should explain that fine with magic fire not behaving like mundane fire. It's the 'magic so no science' that annoys me. There should be a difference between making Fireball 2: Inferno Boogalo from scrat and doing it knowing 15 fire spwl and their interactions.


Generally people try not to annoy other people.

Hey, he started it by allowing me to play the scientist in a zombie apocalypse game. If he wanted me to bash heads instead of experiment he should have said that when I made the dude.


Taoism isn't really a thing in DnD. I mean, unless your DM allows it, but that's always the caveat to everything.

I know, I used it as it's a common archetype in fiction where use of the scientific method is a valid in-character action in games. Ironically, possibly in a setting where shooting fire from your hands isn't strictly considered magic.

[krugaan]

I should explain that fine with magic fire not behaving like mundane fire. It's the 'magic so no science' that annoys me. There should be a difference between making Fireball 2: Inferno Boogalo from scrat and doing it knowing 15 fire spwl and their interactions.


Lol at bolded.

Hahaha, yeah, fine, but the effect it produces should always be the same, because RAW. A different effect is a different spell, and there is research for that. If you want the DM to tell you how mechanically the spell works and the whole Vancian system in general, fine, but most DMs are not stupid enough to open that can of worms.



Hey, he started it by allowing me to play the scientist in a zombie apocalypse game. If he wanted me to bash heads instead of experiment he should have said that when I made the dude.


Obviously he didn't think that one through.


I know, I used it as it's a common archetype in fiction where use of the scientific method is a valid in-character action in games. Ironically, possibly in a setting where shooting fire from your hands isn't strictly considered magic.

I know, but you're trying to mix and match systems here. 5E is the way it is, for some very good reasons which people seem to like. If you want physics / science heavy discussion go visit the Minor Illusion thread.

[TheTeaMustFlow]

Exce the general of fantasy is 'like reality unless otherwise noted'. While I'll agree that magic doesn't have to strictly follow the laws of physics, getting rid of gravity because 'it's fantasy' is just silly.

Actually, something like that sounds fun. Astral Plane campaign anyone? I never liked the space-time continuum anyway.

[RickAllison]

Actually, something like that sounds fun. Astral Plane campaign anyone? I never liked the space-time continuum anyway.

Explain it away as being within a multiple-star solar system around the subject space! For the planet-sized chunk of space, it has the unique feature of having effectively zero-Gs, but still an atmosphere.

[JoeJ]

Except for the fact that magic is easily repeatable. Get 500 fire spells, cast them all a half dozen times and you can start working out what makes them differ. It might be impossible to deduce the entirity of the rules in one lifetime, but you can work stuff out.

Even if the differences between them follow some sort of rule, which is by no means certain with magic, there's no guarantee that the rule is simple enough for your character to understand.

[smcmike]

What about Fire Bolt, Burning Hands, Hellish Rebuke, Flaming Sphere, and all those ones I've forgotten that are in the PhB.

I should explain that fine with magic fire not behaving like mundane fire. It's the 'magic so no science' that annoys me. There should be a difference between making Fireball 2: Inferno Boogalo from scrat and doing it knowing 15 fire spwl and their interactions.

They don't really interact, per the rules, though, and if they did I can imagine it still wouldn't quite scratch your itch.

Or, to put it another way, there are already numerous ways in the PHB to become particularly adept at use of fire spells. Elemental Adept, for instance, or the School of Evocation. You can explain either of these abilities with a bit of mumbo jumbo about all your detailed experimenting.

It's when you start asking for a second rule system, explaining how exactly the magic works within the world, that you get into trouble. I mean, if everyone at the table is interested in that sort of thing, that's cool, but then you run into the problem where the DM's individual concept of magic (it all runs on the souls of babies!) might start interfering with the RAW.

[JoeJ]

Exce the general of fantasy is 'like reality unless otherwise noted'. While I'll agree that magic doesn't have to strictly follow the laws of physics, getting rid of gravity because 'it's fantasy' is just silly.

No one is getting rid of gravity. I mean, sure it stops at a certain range, and it's either full strength or none, and even small objects have normal gravity until they get close enough to a larger object for their gravity fields to merge, and on elongated objects gravity pulls to a plane rather than a point so you can walk on the decks of ships in space (and upside down on the bottoms of those ships), and the largest structures known to exist somehow have no gravity at all, but nobody is getting rid of gravity.

[Regitnui]

This is wrong on so many levels. While rules should not be interpreted overly strictly (which leads to either the commoner railgun or the commoner teleporter) a world with magic should still have the scientific method, if a different body of scientific knowledge.

You know what happens when you apply the scientific method to magic? You get Eberron. Eberron's entire schtick is magic applied as science. So you have a continent-wide telegraph powered by sending and a rail system pulled by air elementals. While the average Sivis gnome has less idea of how the sending spell works than most people IRL about the internet, they can invent faster and better ways of using the spell.

Think of it this way. The average app designer doesn't go "why does the internet work?", they instead say "how can we use this in a new way". The gnomes don't ask "why does sending let us say words to people half a mile away", they ask "how can we send to people across the ocean".

[Lombra]

Science lol

[Dr. Cliché]

Flammable means *easily* set on fire. That's the whole point of having 'Flammable' as a warning, really - these are materials that can be easily ignited by a small spark or flame, and which will then fuel a larger fire.

There may be a bit of leeway regarding what constitutes 'easily', but if a material will only burn if placed in the heart of a star, I think we can reasonably discount it. :smalltongue:

[Anonymouswizard]

You know what happens when you apply the scientific method to magic? You get Eberron. Eberron's entire schtick is magic applied as science. So you have a continent-wide telegraph powered by sending and a rail system pulled by air elementals. While the average Sivis gnome has less idea of how the sending spell works than most people IRL about the internet, they can invent faster and better ways of using the spell.

Think of it this way. The average app designer doesn't go "why does the internet work?", they instead say "how can we use this in a new way". The gnomes don't ask "why does sending let us say words to people half a mile away", they ask "how can we send to people across the ocean".

Yep, and they also might think 'hm... message is similar to sending but acts differently, maybe I should look into that'.

For what it's worth, I personally like Eberron the most precisely because of this scientific approach to magic. I might run it (the 3.5 version) in September because of this, and I will allow players who are interested to investigate magic. I agree that this shouldn't allow them to break game rules, I never have when doing this stuff, but why is this considered wrong bad gameplay whereas lugging around a 10 foot pole, a 12 foot pole, a 6 foot pole, and a bad of marbles considered just playing the game?

[smcmike]

Yep, and they also might think 'hm... message is similar to sending but acts differently, maybe I should look into that'.

And then what? That's the question. I would assume that a character might have all sorts of theories about the nature of magic, and might spend tons of time practicing it or experimenting or whatever. I just don't see how you translate that into the game, beyond spinning some stories about what your character does in his downtime.

[Markoff Chainey]

I really do appreciate it when players have a scientific mindset, especially when they are applying their theories and those deal with fire, like in this comic (http://www.lfg.co/page/978/)(LFG)

Inflammable... bah! :smallbiggrin:

[Regitnui]

And then what? That's the question. I would assume that a character might have all sorts of theories about the nature of magic, and might spend tons of time practicing it or experimenting or whatever. I just don't see how you translate that into the game, beyond spinning some stories about what your character does in his downtime.

In the case of Eberron? Especially if the character's a gnome, they're going to have House Sivis very interested in her research, to the point where they're the character's main sponsor or a major antagonist undermining the party's efforts just to slow or stop the character's research. In the former case, the player might be able to call on favours from the House of Scribing (identity documents, free legal service, priority message services). In the other case, players find patrons can't contact them easily, criminal opponents of the party never seem to get caught, the player who steps over the line of the law might be thrown in jail...

[Shining Wrath]

As a DM, I am fine with a wizard who wants to apply the scientific method and study magic systematically. It's very in-character, I might even award an inspiration point or two.

But ...

you will never be significantly more powerful as a result. Never. The scientific method would not, at my table, lead to being a better wizard. Not because I don't believe in science; because I believe you are not the mutiverse's first wizard, nor the first to try systematic study, nor even among the first one billion wizards in the multiverse to try systematic study using the scientific method. That's how things like Wish came into existence; generations of wizards building on previous study, learning and adapting and advancing the Art Magical. The spells in the PHB and EE and SCAG represent the results of systematic study. You will not improve on them. You will not discover some essence to magic no one else knows. You will not know more about magic than Boccob or equivalent deities.

You may invent a new spell not in the books. It will produce about the same level of effect for a given spell slot as the existing spells. That's fun! But "hey I'm gonna be uber because I study magic scientifically" is right out.

[Knaight]

You know what happens when you apply the scientific method to magic? You get Eberron. Eberron's entire schtick is magic applied as science. So you have a continent-wide telegraph powered by sending and a rail system pulled by air elementals. While the average Sivis gnome has less idea of how the sending spell works than most people IRL about the internet, they can invent faster and better ways of using the spell.

Think of it this way. The average app designer doesn't go "why does the internet work?", they instead say "how can we use this in a new way". The gnomes don't ask "why does sending let us say words to people half a mile away", they ask "how can we send to people across the ocean".

That's not science, it's engineering; similarly the average app designer might qualify as a software engineer, but they aren't a scientist.

[HoodedHero007]

But then, there is the whole "worn or carried rule" of course

[Vogonjeltz]

PSA: This is yet another "How to break the game with a cantrip by throwing "science" with a magic hand till you choke on it... on the magic hand, not the science" topic. Do not take this too seriously or at all.

But really shows how lazy OP is, why not burn the air since air is an unattended object and since all the air is burnt you will cause an extinction level event. (Do not take this seriously, it is to show how lazy and pointless this entire exercise is).

All this does is to make it blatantly clear that the game does not regard air as neither flammable, nor an object, nor hittable.

Also, the term flammable = easily set on fire.

Water isn't easy to set on fire. Unobtanium may be easily set on fire, but it must be hit first and it can't be attended, which presumably means the attendee is able to prevent it from being set on fire or put it out quickly. If you as a DM want to make an exception for a highly flammable object, I'm sure the player could make a good case for allowing it, although whoever was attending would probably want to make a roll to stop the hit from happening at all.

[R.Shackleford]

The biggest thing that bugs me about fire spells, specifically fireball, is that it acts like a liquid.

Which means you can't dodge it while in the space. Even if you protect vulnerable areas, the rest of you is getting hit by fire.

Which means it should be a Constitutiin Save to resist/ignore the damage of the fire.

[Shaofoo]

All this does is to make it blatantly clear that the game does not regard air as neither flammable, nor an object, nor hittable.

Also, the term flammable = easily set on fire.

Water isn't easy to set on fire. Unobtanium may be easily set on fire, but it must be hit first and it can't be attended, which presumably means the attendee is able to prevent it from being set on fire or put it out quickly. If you as a DM want to make an exception for a highly flammable object, I'm sure the player could make a good case for allowing it, although whoever was attending would probably want to make a roll to stop the hit from happening at all.

You do realize that I just said not to take this seriously, right? It was right there in the text that you quoted.

And as was said before, easily can be left for debate. Of course reasonable people not looking to break the game might say things like "exposed to an open flame will be enough to set it on fire" and while unobtanium can be easily set off by flame (unobtanium itself being a fully meaningless term that can be literally anything). Of course if it is the unobtanium as the player says I would wonder why isn't the object in some sort of protective case if it is to go nuclear when struck with fire (and I wonder the mass of something that can generate so much energy so quickly especially since flammability isn't a truly efficient way to create energy).

The only way I can see a DM even allowing such a thing is if he wants to push the reset button on the campaign and rocks falls everyone dies is played out.

And I personally wouldn't allow inventory destruction unless there is an effect that specifically mentions it. If that is what you want to do then go for it but the players in my games don't like having random arrows and bolts shatter bottles and blow up their alchemist fires as a whole and I don't, because I find it a cheap way to raise the stakes and plus we have to sit down for a while and argue whether the position and blow would totally have destroyed the item.

[RickAllison]

I would like to point out that if there is any debate over what constitutes flammable, a good reference can be industrial fire codes.

[Knaight]

The biggest thing that bugs me about fire spells, specifically fireball, is that it acts like a liquid.

It acts like a fluid, but a better analog than a liquid is pressurized air - which absolutely can be avoided while still within the high pressure radius, provided you get behind something. Completely dodging fire in an empty room is pretty ridiculous, but mitigating it by ensuring less of you gets hit, hiding at least partially behind any number of obstacles that only really qualify as rough terrain, and doing other things is reasonable. All of that would be a dex save.

[KorvinStarmast]

As a DM, I am fine with a wizard who wants to apply the scientific method and study magic systematically. It's very in-character, I might even award an inspiration point or two.

But ...

you will never be significantly more powerful as a result. Never. The scientific method would not, at my table, lead to being a better wizard. Not because I don't believe in science; because I believe you are not the mutiverse's first wizard, nor the first to try systematic study, nor even among the first one billion wizards in the multiverse to try systematic study using the scientific method. That's how things like Wish came into existence; generations of wizards building on previous study, learning and adapting and advancing the Art Magical. The spells in the PHB and EE and SCAG represent the results of systematic study. You will not improve on them. You will not discover some essence to magic no one else knows. You will not know more about magic than Boccob or equivalent deities.

You may invent a new spell not in the books. It will produce about the same level of effect for a given spell slot as the existing spells. That's fun! But "hey I'm gonna be uber because I study magic scientifically" is right out.This. There is enough material in the game to enjoy as it is.


But then, there is the whole "worn or carried rule" of course that is done to streamline play. If you want to go back to 1e days and make each item makes its own saving throw versus dragonbreath, or a spell, go right ahead.
Roll a d20 for each item in the inventory on the sheet and slow the game down long enough to drive your players away from the table.
Be my guest.

[R.Shackleford]

It acts like a fluid, but a better analog than a liquid is pressurized air - which absolutely can be avoided while still within the high pressure radius, provided you get behind something. Completely dodging fire in an empty room is pretty ridiculous, but mitigating it by ensuring less of you gets hit, hiding at least partially behind any number of obstacles that only really qualify as rough terrain, and doing other things is reasonable. All of that would be a dex save.

Pressuirized air that fills its space instantaneously is no different than saying it's a liquid for this issue.

You aren't really doing to dodge it. You may hide your sensitive areas but you can't protect them all (face, ears, junk, exposed skin, pick one).

A Constitution save still makes more sense. You are shrugging off the damage and effect. Hell, even in a normal fireball you should be able to use a Con saving throw.

Frostbite and many other spells/features already show that Con is used to save against physical effects.

With the way 5e has set up their saving throw system (i prefer the 3e/4e hybrid system) The defender should always get a choice of two saves. When it comes to maneuvers this is already an option and it doesn't slow shut ing down.

Fireball: Con or Dex save
Phantasmal Force: Int or Wis save
Banishment: Cha or Wis save.

This would really cut down on just how powerful cherry picking saves really is and it makes the two systems fall more in line.

Why can a person decide to use Strength or dexterity to get away from a grapple but not strenth or dexterity to get away from magical plant grappling you? I mean, does the magic automatically get to choose how your PC reacts to the world around it before you even get to save?

Shouldn't you get a mental save first to stop said magic from determining how you would react to it?

Too troublesome.

All spells in this system should give two ways to save... A "resist" and a "dodge".

[Knaight]

Pressuirized air that fills its space instantaneously is no different than saying it's a liquid for this issue.

It doesn't need to fill the space instantaneously, just fairly quickly. Taking a second or two is entirely reasonable.

As for it being different from a liquid, they flow differently. If you're hiding in a ditch under the place pressurized air originates from, the high pressure air will mostly flow over the ditch, creating a localized low pressure zone. It's a fairly safe place to hide. If you're hiding in a ditch when a liquid rushes over it, you just get drenched from above. Meanwhile, hiding on the other side of a ditch for a liquid could be helpful, although given the volumes involved it's far from a perfect defense.

[RickAllison]

It doesn't need to fill the space instantaneously, just fairly quickly. Taking a second or two is entirely reasonable.

As for it being different from a liquid, they flow differently. If you're hiding in a ditch under the place pressurized air originates from, the high pressure air will mostly flow over the ditch, creating a localized low pressure zone. It's a fairly safe place to hide. If you're hiding in a ditch when a liquid rushes over it, you just get drenched from above. Meanwhile, hiding on the other side of a ditch for a liquid could be helpful, although given the volumes involved it's far from a perfect defense.

For that matter, hiding that way applies to high-pressure liquids as well! Spray water with a high-pressure nozzle and hiding in a ditch becomes a viable tactic. This can even be seen on something as low-pressure as the Splash Mountain ride. A common tactic for mischievous youngsters (and a few older pranksters *coughmecough*) is to duck down in the front row so a family member in the second gets the full brunt while you are relatively dry!

[R.Shackleford]

For that matter, hiding that way applies to high-pressure liquids as well! Spray water with a high-pressure nozzle and hiding in a ditch becomes a viable tactic. This can even be seen on something as low-pressure as the Splash Mountain ride. A common tactic for mischievous youngsters (and a few older pranksters *coughmecough*) is to duck down in the front row so a family member in the second gets the full brunt while you are relatively dry!

To bad a ditch won't help you against a fireball as it fills its space, instanenously, with harmful fire damage 20' radius isn't just horizontal.

Edit

Just so people know how fireball works (like a liquid)

3rd-level evocation

Casting Time: 1 action; Range: 150 feet; Components: V, S, M (a tiny ball of bat guano and sulfur); Duration: Instantaneous

A bright streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one.

The fire spreads around corners. It ignites flammable objects in the area that aren’t being worn or carried.
****


Fireball moves around corners and fills the 20' radius instantly.

Fireball could also be a cat, cats are liquid after all.

[Mr.Moron]

Except for the fact that magic is easily repeatable. Get 500 fire spells, cast them all a half dozen times and you can start working out what makes them differ. It might be impossible to deduce the entirity of the rules in one lifetime, but you can work stuff out.

Now if you want to have magic where the scientific method isn't valid you can have it, but it makes wizards frustrating to play.

It's fully possible that the underlying principles of magic are unobservable. Imagine for a moment trying to find answers on the mechanisms of say how anger works without access to brain scans, an understanding of chemistry sufficient to comprehend things like neurotransmitters. The task would simply be impossible because the mechanisms would be beyond your capacity to observe and measure them. Now imagine that for whatever reason the laws of physics were such that brain scans were impossible, or that the human brain was cognitively limited in such a way the concepts were simply beyond them. Now it isn't just matter of insufficient technology, the task is fundamentally impossible.

A mouse will never comprehend how the mouse's brain works. It lacks the ability to create the tools needed to observe the function of the brain and lacks the cognitive ability to comprehend the concepts even if it did observe. Similarly it is not conceptually impossible that there are things beyond the human ability to observe (or create things that can observe them), and/or our ability to comprehend them when observed.

Similarly what makes for slight variations in the performance of magic may simply beyond the capacity of mortals to observe, and beyond their ability to comprehend it could they observe it. The true fundamentals of magic being to us, as electromagnetism is to insects. Something which can interact with them, something they can even manipulate and and utilize in some cases. However the rules which govern it are forever beyond them, so far beyond them in fact they have no notion that there would be anything to be found.

[TheTeaMustFlow]

As a DM, I am fine with a wizard who wants to apply the scientific method and study magic systematically. It's very in-character, I might even award an inspiration point or two.

But ...

you will never be significantly more powerful as a result. Never. The scientific method would not, at my table, lead to being a better wizard. Not because I don't believe in science; because I believe you are not the mutiverse's first wizard, nor the first to try systematic study, nor even among the first one billion wizards in the multiverse to try systematic study using the scientific method. That's how things like Wish came into existence; generations of wizards building on previous study, learning and adapting and advancing the Art Magical. The spells in the PHB and EE and SCAG represent the results of systematic study. You will not improve on them. You will not discover some essence to magic no one else knows. You will not know more about magic than Boccob or equivalent deities.

You may invent a new spell not in the books. It will produce about the same level of effect for a given spell slot as the existing spells. That's fun! But "hey I'm gonna be uber because I study magic scientifically" is right out.

What this guy said. Apart from in a time travel scenario or somesuch, I have a special hatred for the whole 'One Man Scientific Revolution' trope.

[Shining Wrath]

It's fully possible that the underlying principles of magic are unobservable. Imagine for a moment trying to find answers on the mechanisms of say how anger works without access to brain scans, an understanding of chemistry sufficient to comprehend things like neurotransmitters. The task would simply be impossible because the mechanisms would be beyond your capacity to observe and measure them. Now imagine that for whatever reason the laws of physics were such that brain scans were impossible, or that the human brain was cognitively limited in such a way the concepts were simply beyond them. Now it isn't just matter of insufficient technology, the task is fundamentally impossible.

A mouse will never comprehend how the mouses brain works. It lacks the ability to create the tools needed to observe the function of it's brain and lacks the cognitive ability to comprehend the concepts even if it did observe. Similarly it is not conceptually impossible that there are things beyond the human ability to observe (or create things that can observe them), and/or our ability to comprehend them when observed.

Similarly what makes for slight variations in the performance of magic may simply beyond the capacity of mortals to observe, and beyond their ability to comprehend it could they observe it. The true fundamentals of magic being to us, as electromagnetism is to insects. Something which can interact with them, something they can even manipulate and and utilize in some cases. However the rules which govern it are forever beyond them, so far beyond them in fact they have no notion that there would be anything to be found.

Further, in a world where gods dispense magic to their clerics, with spells that in some cases are identical to those cast by wizards; and also we have sorcerers, who simply tell the universe what it is going to do by sheer force of personality and succeed - it is entirely possible that the laws of magic are not only unknowable, but deliberately obscured by Powers beyond the ability of mortals to challenge.

Arcane magic is then a Promethean effort, deliberately unveiling that which god(s) want hidden and subject to divine meddling. In such a situation, the scientific method is going to encounter problems with the reproducible aspect of experiments, as the success or failure of an experiment may depend upon whether or not the gods and / or their minions notice and permit it to function.

[Ravens_cry]

Really, though, the correct answer is "science has no place in a world with wizards" and leave it there.
Actually, D&D spells are quite scientific. They are easily repeatable with results that, while variable, are within carefully controlled parameters. It's just that the laws of physics (which includes magic) within a D&D world are quite a bit different from out own.

[Mr.Moron]

Actually, D&D spells are quite scientific. They are easily repeatable with results that, while variable, are within carefully controlled parameters. It's just that the laws of physics (which includes magic) within a D&D world are quite a bit different from out own.

You're also really only stating qualities of the spells as written in the book, which is an abstraction meant to give us a good adapter on the game world. The game dictates characters must eat but doesn't delve into nutrition, taste and million other nitty gritty details that really change & inform the process of eating. It ignores those things because we want to play a game about adventurers doing adventurer things not meal planners & nutritionists. The game also does not even explictly call out it's glossing over a million details about biology and nutrition it's just that far out of scope. Heck the writers & designers probably didn't even think about the fact they were glossing over such details it so irrelevant it was glossed over without making a conscious decision to do so.

It may be that "Fireball" is no more a finely grained picture of what goes into casting spell and producing a large bang of heat and energy than the food rules present a fine grained picture of biological processes. Sure wizards can consistently get a flash of heat and concussive force but maybe every time you do it's a pretty different process and there are million variables the game doesn't go into and they're not always the same diameter and the color is always different for reasons nobody understand.

Sometimes an orange is rotten but rotten oranges have nothing to do with telling exciting stories about adventurers so they rules don't cover "Oh yeah you need vitamin C so you need oranges, but sometimes the orange is rotten and it doesn’t' count" because such things aren’t' conducive to having cool stories about adventurers doing cool things while playing a little tactical board game about it. It's irrelevant and off tone so forget it. Perhaps sometimes when do what you do to cast fireball it conjures a goat. However "Oh yeah you can cast fireballs, so you need to get bat guano but sometimes the the way the spell wants you to hold it changes and you can't really tell so sometimes you get a goat" isn't really conducive to having cool stories about adventurers doing cool things while playing a little tactical board game about it.

Certainly "spells can do stuff you don't expect" is a common fantasy trope, and the default flavour is open ended enough to allow for such things.

[pwykersotz]

You're also really only stating qualities of the spells as written in the book, which is an abstraction meant to give us a good adapter on the game world. The game dictates characters must eat but doesn't delve into nutrition, taste and million other nitty gritty details that really change & inform the process of eating. It ignores those things because we want to play a game about adventurers doing adventurer things not meal planners & nutritionists. The game also does not even explictly call out it's glossing over a million details about biology and nutrition it's just that far out of scope. Heck the writers & designers probably didn't even think about the fact they were glossing over such details it so irrelevant it was glossed over without making a conscious decision to do so.

It may be that "Fireball" is no more a finely grained picture of what goes into casting spell and producing a large bang of heat and energy than the food rules present a fine grained picture of biological processes. Sure wizards can consistently get a flash of heat and concussive force but maybe every time you do it's a pretty different process and there are million variables the game doesn't go into and they're not always the same diameter and the color is always different for reasons nobody understand.

Sometimes an orange is rotten but rotten oranges have nothing to do with telling exciting stories about adventurers so they rules don't cover "Oh yeah you need vitamin C so you need oranges, but sometimes the orange is rotten and it doesn’t' count" because such things aren’t' conducive to having cool stories about adventurers doing cool things while playing a little tactical board game about it. It's irrelevant and off tone so forget it. Perhaps sometimes when do what you do to cast fireball it conjures a goat. However "Oh yeah you can cast fireballs, so you need to get bat guano but sometimes the the way the spell wants you to hold it changes and you can't really tell so sometimes you get a goat" isn't really conducive to having cool stories about adventurers doing cool things while playing a little tactical board game about it.

Certainly "spells can do stuff you don't expect" is a common fantasy trope, and the default flavour is open ended enough to allow for such things.

^^Also this. (Yes, I know, my contributions to this thread are truly a sight to behold :smalltongue:)

[smcmike]

^^Also this. (Yes, I know, my contributions to this thread are truly a sight to behold :smalltongue:)

That's ok. I agree wholeheartedly.

[Vogonjeltz]

You do realize that I just said not to take this seriously, right? It was right there in the text that you quoted.

And as was said before, easily can be left for debate. Of course reasonable people not looking to break the game might say things like "exposed to an open flame will be enough to set it on fire" and while unobtanium can be easily set off by flame (unobtanium itself being a fully meaningless term that can be literally anything). Of course if it is the unobtanium as the player says I would wonder why isn't the object in some sort of protective case if it is to go nuclear when struck with fire (and I wonder the mass of something that can generate so much energy so quickly especially since flammability isn't a truly efficient way to create energy).

The only way I can see a DM even allowing such a thing is if he wants to push the reset button on the campaign and rocks falls everyone dies is played out.

And I personally wouldn't allow inventory destruction unless there is an effect that specifically mentions it. If that is what you want to do then go for it but the players in my games don't like having random arrows and bolts shatter bottles and blow up their alchemist fires as a whole and I don't, because I find it a cheap way to raise the stakes and plus we have to sit down for a while and argue whether the position and blow would totally have destroyed the item.

Apparently one person's serious is another's whimsy eh?

[Regitnui]

Here's a thought; maybe the PHB spells are the result of the scientific method being applied to spells. Bat guano of a certain amount and vintage is the most efficient material component for a fireball spell. Putting your thumbs together with fingers splayed gets the best possible range on the burning hands spell. While I agree one PC Wizard isn't going to revolutionize the world of spellcasting, if a player is diligent enough about their roleplay that they describe their character constantly experimenting, why not reward them with slightly more effective spells?

"As the fireball explodes near the imp, it shrieks in surprise as the flames actually burn it! It disappears, no doubt to report to its superiors what it has learned today." And the players spend the rest of the game being bothered by 'friendly' demons and devils who want to know how this mortal wizard overcame a devil's fire immunity and if they can use it themselves for their Blood War.

[Mith]

I wouldn't describe bypassing immunity as "slightly more effective". If you can bypass immunity, that is a big deal.

The best mechanical bonus I would give is raise the floor of the spell with perhaps "1s are counted as 2" while keeping the same damage cap (so a 1d8 spell would go 2,2,3,4,5,6,7,8).

THe only spell I would let bypass resistances is Magic Missile, but that's because I like the idea of the one spell that would eventually take down anything. Unless of course it deflects the spell.

[Regitnui]

I wouldn't describe bypassing immunity as "slightly more effective". If you can bypass immunity, that is a big deal.


Precisely why I impose the consequences of being pursued by demons and devils for the rest of your natural existence. Maybe it only works on imps or devils. Perhaps it reduces their immunity to resistance. Maybe it was a one-time nigh-impossible set of circumstances (cast in a manifest zone to the fire plane at high noon on the summer solstice while chewing gum). That's what experimentation is like.

[Shaofoo]

Apparently one person's serious is another's whimsy eh?

Unless you believe in "my fun begins where others ends".

[GreyBlack]

Nor do we see rules for thermodynamics and we fall at faster than the speed of gravity. Have you ever read the rules for survival?

[KorvinStarmast]

Nor do we see rules for thermodynamics and we fall at faster than the speed of gravity. Have you ever read the rules for survival? We could say that a fireball is a magical variation on the mundane explosive/bomb called a Fuel Air Explosive (https://www.youtube.com/watch?v=Jdji4RMec2M)(FAE), of a smaller size than shown in the video. What it isn't, however, is an actual FAE.

[TentacleSurpris]

Stuff catching on fire or not is really more chemistry than physics.

[R.Shackleford]

Nor do we see rules for thermodynamics and we fall at faster than the speed of gravity. Have you ever read the rules for survival?

Real world gravity doesn't have a speed, it is an acceleration.

But the rules do attempt to stay along with real world thermodynamics and gravity.

There is a terminal velocity and there is gravity on the planes.

Cold and hot exist and you can set things on fire.

The rules may or may not be different but there are rules even if we don't know the specifics.

[krugaan]

I'll say it again ... every campaign should have a "physics level" associated with it.

Default is : Newtonian.

[RickAllison]

Also a thing to note: something being considered flammable is dependent on the ambient temperature. Wood is flammable at normal temperatures, but the unobtanium might only be flammable above 1500 degrees Celsius. If you get the temperature that high, you can set it on fire, but you deserve your props by that point.

[R.Shackleford]

I'll say it again ... every campaign should have a "physics level" associated with it.

Default is : Newtonian.

I preferclassical system that made the earth, water, fire, and air. Things made of the same stuff wanted to be together so things made of "earth" would fall to earth, water would go to water (going to earth first and then to water), and so on.

https://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Four_elements_representation.svg/200px-Four_elements_representation.svg.png

Makes for some fun times.

[Knaight]

Also a thing to note: something being considered flammable is dependent on the ambient temperature. Wood is flammable at normal temperatures, but the unobtanium might only be flammable above 1500 degrees Celsius. If you get the temperature that high, you can set it on fire, but you deserve your props by that point.

Temperature and atmospheric conditions.

Just because it isn't flammable in 22% oxygen doesn't mean it isn't flammable in 100% oxygen, and if it still isn't, 100% fluorine will usually get the job done.

[krugaan]

Temperature and atmospheric conditions.

Just because it isn't flammable in 22% oxygen doesn't mean it isn't flammable in 100% oxygen, and if it still isn't, 100% fluorine will usually get the job done.

Hah, I'm pretty sure the atmosphere itself is flammable at 100% oxygen.

[Mith]

Anything left will be finished off when you switch to 100% flourine.

[Shining Wrath]

Temperature and atmospheric conditions.

Just because it isn't flammable in 22% oxygen doesn't mean it isn't flammable in 100% oxygen, and if it still isn't, 100% fluorine will usually get the job done.

Temperature of ignition in 100% fluorine usually much lower. Sometimes "are you above absolute zero? OK, it burns".

[ShikomeKidoMi]

disregarding the whole "magic" part, anyway.
let's take Fire Bolt, a cantrip that, among other things, sets fire to things that aren't being worn or carried.
Let's say Mr. Wizard hurls it at a block of unobtainium, which has a specific heat of 1 trillion joules/ degrees celsius and a burning point of 900 googolplexianth degrees celsius, since it is not being worn or carried, it's set on fire, therefore, the bolt is hot enough to do that, which in most cases, is enough to melt anyone's face of within a 100 mile radius (or something like that)

Your conclusion doesn't follow from your premise. As you've noted, fire spells don't obey the laws of physics (Conservation of energy, anyone?). Maybe it just lights things on fire by infecting them with the essence of fire. Who knows? Who cares?

[R.Shackleford]

Hah, I'm pretty sure the atmosphere itself is flammable at 100% oxygen.

Really, way before that, you just have to worry about everyone and everything you know and love bursting into flames due to friction or some jerk lighting a cig.

[Knaight]

Really, way before that, you just have to worry about everyone and everything you know and love bursting into flames due to friction or some jerk lighting a cig.

You still need the other component of the combustion reaction, pure oxygen with nothing in it won't combust. You also still need a spark. It's just that once you have it the reaction is going to go way faster and to more completion, and the fire is going to spread quickly and spread just fine over any number of things that normally take a concerted effort to burn. Everyone and everything you know and love bursting into flames isn't the big issue, particularly as those sorts of conditions are only going to exist in sealed containers.

That oxygen poisoning is a major issue below even 30% oxygen, and the existence of sealed containers which both contain people and need oxygen level control on the other hand...

[R.Shackleford]

You still need the other component of the combustion reaction, pure oxygen with nothing in it won't combust. You also still need a spark. It's just that once you have it the reaction is going to go way faster and to more completion, and the fire is going to spread quickly and spread just fine over any number of things that normally take a concerted effort to burn. Everyone and everything you know and love bursting into flames isn't the big issue, particularly as those sorts of conditions are only going to exist in sealed containers.

That oxygen poisoning is a major issue below even 30% oxygen, and the existence of sealed containers which both contain people and need oxygen level control on the other hand...

The min/max for oxygen percentage is at like 19% and 22% (in an atmosphere, be it a room, vault, or outside).

Go below or above those percentages and you die very very fast.

It isn't the oxygen that you are worried about burning (is what I meant before). When you get high oxygen levels it allows other things to ignite easier (for the most part, some things get weird). You can start fires with friction (rubbing two sticks togther becomes easier to the point where anyone can do it).

[Knaight]

The min/max for oxygen percentage is at like 19% and 22% (in an atmosphere, be it a room, vault, or outside).
This is at 1 atm, at lower pressures the maximum oxygen goes up a bit.


It isn't the oxygen that you are worried about burning (is what I meant before). When you get high oxygen levels it allows other things to ignite easier (for the most part, some things get weird). You can start fires with friction (rubbing two sticks togther becomes easier to the point where anyone can do it).
Yes, but the things that aren't going to ignite with oxygen still generally won't, which gets back to my point with sealed containers - if you find 100% oxygen environments, it's probably on the inside of a fume hood in a specialized apparatus where there is very little there than can burn.

[Shining Wrath]

We have a tragic example from the real world - Apollo 1 (https://en.wikipedia.org/wiki/Apollo_1). Even NASA didn't account for the effects of pure oxygen on combustibility - although I assure you that they do now.

[NNescio]

Stuff catching on fire or not is really more chemistry than physics.

I played in a game once with Chemistry, Physics, and two kinds of Engineering majors.

We sat down and agreed that "flammable" is best defined by MSDSes (implicitly basing things on atmospheric conditions) and 'reasonable' extrapolation (for materials without MSDS, or composite materials), and not any of the "it can theoretically burn in a furnace or star" or "under elevated partial pressures for oxygen and/or the presence of other oxidizers" arguments.

End result is something that most laymen would come up with, well, just common sense instead of misapplication of 'science'.

(Yes, the Engineers made things go a little out of hand before we agreed on this kind of rules interpretation.)