Originally Posted by
complich8
FMA's "Equivalent Exchange" is closer to the first law of thermodynamics: in a closed system, entropy always increases.
However, it's not a valid metaphor for a lot of things in life, and isn't an ironclad law for the way in which the world works.
Economics considers trade in one of two paradigms: the zero-sum game and the nonzero-sum game. In a zero-sum game, for someone to win, someone else has to lose. This is the idea that toka-kokan is based on, and is grounded in the idea that value is an absolute.
Modern economics recognizes that value is NOT absolute, not an intrinsic property of an object, and thus that the value I ascribe to something can be substantially different than your evaluation of the same thing. If I can find something of yours that has little value to you but great value to me, and you can do the same for me, we can exchange them and both achieve a net gain in value. This is a positive-sum game, and is the foundation of liberal economics (free markets, capitalism as a whole).
In the world, there are zero-sum, positive-sum, and negative-sum situations. Wars of attrition are pretty much never positive-sum: even with a low value to human life, the mere economic cost of such a war is often heavier than the benefits associated with winning it. Free markets are positive-sum, and universal conservation of mass-energy is a zero-sum situation. Saying that any one paradigm defines all given circumstances is patently incorrect.
Incidentally, FMA addresses this towards the end, questioning toka-kokan and its veracity. In the case of human-conjuring, the 'game' was very clearly negative-sum. In the case of other alchemy, it was positive-sum (ie: you got order for free by practicing alchemy, it was essentially free energy).