I've been wondering lately about this third rail of philosophy. Can

[Jenny]

someone tell me about it?
Obviously, the anser is not as simple as going to wikipedia and plagarizing verbatim the entry there.

[angel]

The phrase third rail is a metaphor in politics to denote an idea or topic that is so "charged" and "untouchable" that any politician or public official who dares to broach the subject would invariably suffer politically.

The third rail in a train system is the exposed electrical conductor that carries high voltage power. Stepping on the high-voltage third rail usually results in electrocution. The use of the term in politics serves to emphasize the "shock" that results from raising the controversial idea, and the "political death" (or political suicide) that the unaware or provocative politician would encounter as a result.

Disagreement may occur over whether a specific issue is a "third rail" issue. Nonetheless, the following examples are often "third rail" issues in the United States:

Raising taxes
Eliminating or radically reducing the scope of a major social program, like social security, welfare, or the healthcare system
Cutting funding for law enforcement
Creating a National Identity Card
Ending support for Israel
Legalization of controlled substances
Suggesting that race and crime are related
Third rail issues usually only die when politicians who have proven their credentials on related matters ignore the taboo and openly challenge the controversial issue. For example, ending recognition of the Taiwanese government in favor of the Communist People's Republic of China was long a third rail issue in the United States, until Richard Nixon openly began to establish ties with the PRC. The consensus was that since Nixon had proven himself to be a staunch anti-Communist on other major issues, he could "get away" with doing something that would otherwise appear to be a very pro-Communist gesture. The saying "Only Nixon could go to China" has become a popular explanation of how third rail issues die.

[Yaoi Shonen-ai]

http://en.wikipedia.org/wiki/Third_rail_(metaphor)

[Charles C]

I have never heard of it. Please explain.