Quote:
Originally Posted by finn
Actually, it works as it should.
Actually, the "endpoints" are not important at all.
Yes, it does. It is extremely important to this argument.
You don't start form the other end. You start from the original cost of the advantage.
"Naked" is a limitation worth -30%, which is worth -30 points.
"Not Naked" is a enhancement worth +30%, which is worth +30 point. The 30% is multiplied against the the original 100 point. Not against the 70 points you call the "other end".So, a Jumper advantage with a "Naked" and "Not Naked" is worth
100 - 30 +30 = 100
That's how GURPS math works as written.
This math has it's own set of problems, but not the issue you mentioned.
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No, that's not how it works as written. GURPS math isn't a different thing from regular math.
PK's calculation as written in the snippet isn't actually RAW. It's an argument following the principles of other examples that are RAW about calculating unknown values.
For example, and I'm doing this from memory, there was a calculation for an Enhancement where the effects against Blondes were doubled, which wasn't a standard enhancement. The argument for valuing it ran roughly as follows: We do have an limitation for halving the effect. Affects only Blondes is a 30% Limitation. If the population is 100%, then Affects Non-Blondes is 100% - 30% = 70% because any individual in the population is either blonde or not-blonde. (Mathematically, the conditions are exhaustive and mutually exclusive, i.e., there can be no one is both blond and non-blond nor anyone who is neither blond or non-blond). We can apply the limitation halving the effect to the 70% non-blondes. We now have a power that has half its effectiveness against non-blondes and a proper price for the value of that Limitation. But a Limitation halving the effectiveness of the power vs. non-blonds gives exactly the same effect as an enhancement that doubles the effectiveness of the power against blonds. All we need to do is buy the power at the level we want Blonds to be affected at, apply the Limitation: halved effect against non-blonds, and call it doubled effect against blonds. Done.
Now look at PK's argument and the fallacy contained therein. He says that it's a 30% Enhancement because adding 30% to 70% gives 100% cancelling the Limitation and getting us back to our original value.
The fallacy in the argument is that he's not adding a +30% Enhancement to get us back to the original 100 points which is what an Enhancement needs to do. He's simply cancelling the original -30% Limitation and calling it an Enhancement.
Here's why doing that is a problem. Adding the 30% back is adding back the 30% calculated from the 100 point original advantage. In a sense, that's okay because we're adding back 30 points to get 100 points. But that's the nub of the problem.
We want to add those 30 points back to our limited advantage! Those 30 points are
exactly what the Enhancement negating the 30 point Limitation is worth. The problem with it as a % Enhancement is that it's 30% of the Advantage without the Limitation. The reason we presumably want its value as an enhancement is to apply to an advantage where arriving naked is a built-in part of the advantage and we don't know what the price of that advantage would be when enhanced.
The only way we can get the value of it as an enhancement is to find what those 30 points are worth as a % enhancement to the 70 point Advantage with the Limitation and as I mentioned previously, its an inconvenient +43%. When you are Enhancing an advantage to not arrive naked, you need to add 43% of the value of arriving naked.
For example, if you want to go from Jumper (naked) at 70 points to Jumper (not naked); it's a 43% Enhancement. 43% of 70 is 30 points, so for 100 points (the original 70 points plus the 30 point enhancement), you can have Jumper (not naked).
100 points -30 points +30 points = 100 points is fine.
100%-30%+30% =100% is fine, too.
However: If I have 100 jellybeans and lose 30% of them, what percentage of the remaining jelly beans do I have to find to have 100 jelly beans again? The answer isn't 30%, but it's what you're insisting on.