“Humankind cannot gain anything without first giving something in return. To obtain, something of equal value must be lost. That is alchemy’s first law of Equivalent Exchange. In those days, we really believed that to be the world’s one, and only truth.”

—Alphonse Elric, in the first opening to Fullmetal Alchemist

The concept of Equivalent Exchange introduced in the anime quoted above inspired the title of this blog. “To obtain, something of equal value must be lost.” Though this term was recently coined, the concept is a familiar one and has been around for a long time. It is found as guides, rules, and laws in philosophy, religion, and science. For example:

• Do unto others as you would have them do unto you.
• Don’t take more than you give.
• Give and you shall receive.
• What goes around comes around.
• There’s no such thing as a free lunch.
• You get what you pay for.
• You get what you deserve.
• An eye for an eye, a tooth for a tooth.
• You scratch my back, and I’ll scratch yours.
• Energy is neither created nor destroyed.
• Every action has an equal and opposite reaction.
• Yin and yang.
• Karma.

I’m sure many more can be listed. I invite my readers to submit them.

These are all conservation laws: total value is maintained, even while it changes hands. And they certainly seem to be “conservative”:  all things being equal, they usually hold.

That being said, this blog isn’t specifically about “equivalent exchange”, except for hopefully obtaining the value of knowledge for the effort expended. Instead, I hope to explore a common thread that runs through philosophy, logic, and semiotics in the form of “double duals” (which themselves seem to have the property of equivalent exchange), with the goal of understanding and classifying different philosophical subjects and systems, exploring the nature of pluralism, and enhancing dialogue between opposing viewpoints. The image of the Tower of Babel in the title banner was chosen because public discourse has become fragmented and even broken.