It is easy to argue that the type of act that Ted mentioned above is performed out of self interest, however it is a meaningless argument. The "self interest" you are speaking of in order to make this claim is very broadly defined; the meaning must resolve to something like "in accordance with one's own personal desires." Of course this is true, but the claim thus is something like "People do things because they want to." Not a very profound statement.

Note that the definition of "self interest" you are left with does not correspond to the generally understood definition of the term. The fallacy comes when you then try to take the (true) statement "One only acts out of self interest" and put it in another context.

When you take the self interest statement and claim that therefore everyone is selfish, or that acting in a "self interested" manner is justified or beneficial, you are now using a different, more narrow definition of self interest. This "self interest" is associated with greed and selfishness, and is not at all similar to the type of "self interest" used to prove the original statement.

The fallacy is thus similar to me saying:

"Every type of canine is a dog. The law says that one can own a dog as a pet. Therefore I can own a wolf as a pet"

Each statement is true... but the "dog" I am talking about in the first sentence is broadly defined to encompass the taxonomic family, whereas the "dog" in the second sentence is narrowly defined to be the domestic dog, Canis familiaris.

I suppose my point simply is: Of course all action is, in a very broad sense, directed at the self. We generally know what people mean when they say duty, however, and because of this, the word does have a real meaning.

Kate's point that the term "duty" can be used to excuse the coercive power of government or society is well taken, but I don't think we need to get rid of the word to make the point. Like every word, "duty" can be understood in different ways - just be clear how you mean it when you use it, and we will all be happy and intelligible.

-- TheodoreSmith - 26 Jan 2008