fungibility n : the quality of being capable of exchange or interchange [syn: exchangeability, interchangeability, interchangeableness] [ant: unexchangeability]

Fungibility is the property of a good or a commodity whose individual units are capable of mutual substitution.

Fungibility versus liquidity

Fungibility is different from liquidity. A good is liquid and tradable if it can be easily exchanged for money or another different good. A good is fungible if one unit of the good is substantially equivalent to another unit of the same good of the same quality at the same time and place.

Fungibility does not imply liquidity, and liquidity does not imply fungibility. Jewels can be bought and sold (the trade is liquid), but individual diamonds are not interchangeable (diamonds are not fungible). Zimbabwean dollar bank notes are interchangeable in London (they are fungible there), but they are not easily traded there (they are not liquid in London).

Fungibility in economics

Examples of highly fungible commodities are petroleum (gasoline), electricity, precious metals, and many currencies.

Fungibility has nothing to do with the ability to exchange one commodity for another. It has everything to do with exchanging one unit of a commodity with another unit of the same commodity.

Fungibility in international relations

In international relations, the term fungibility is usually applied to the power of states. International relations theorists who believe that power is fungible see different types of power as reinforcing each other. By way of analogy: with power as a fungible commodity, a state may translate its economic power into military power (e.g. buy some tanks, military aircraft, and armaments) and vice versa (sell some tanks and aircraft). A major debate in international relations is the degree of fungibility between hard power and soft power.

Fungibility in law

In legal disputes, when one party is compelled to remedy another party as the result of a ruling or adjudication, the appropriate legal remedy may depend on the fungibility of the underlying right, obligation or property interest that is intended to be restored. Depending on whether the interests of the aggrieved party are fungible (a determination made by the trier of fact), the appropriate remedy may change. For example, a court may require specific performance as a remedy for breach of contract, instead of the more favored remedy of monetary damages.

Fungibility in science

In Does God Play Dice? The New Mathematics of Chaos, the mathematician Ian Stewart argues that fungibility applies to science as well. The example he uses is that subatomic particle theory is fungible when studying molecules "provided it led to the same general feature of a replicable molecule."

Another example is the concept of mass, either gravitational or inertial mass. Mass is fungible in all observationally consistent theories of gravitation. All compositions of matter fall identically in vacuum, including binding energies.

Perhaps the ultimate example of fungibility in science is that of identical particles. In quantum mechanics, two elementary particles of identical mass, charge, and spin can be interchanged without any discernible effect. In fact, it is impossible to discern between the particles even in principle. This 'mandatory fungibility' leads to some surprising conclusions, such as the Pauli exclusion principle.

Fungibility in typography

Johanna Drucker discusses the idea that fungibility may also exist in respect of typography and the recording of information. In her article "The Future of Writing in Terms of its Past: The New Fungibility Factor" she argues that in our new age of technology, the form that written language takes is no longer an important part of the message it conveys. This is due to the fact that the appearance of a message can be changed at the click of a mouse button.

See also

• Gold standard
• Private currency
• Silver standard

References