Hypocritic Oath

As it turns out, sarcasm is a form of irony. Looking it up in an online dictionary, saying something like "Lovely weather" when it is downpour is considered irony. There's also dramatic irony when you're watching, say, a play, and you know that a character expects one thing, but the opposite will occur (for example, expects to be rich and famous, and ends up poor and unknown).

Hypocrisy, to my mind, is related, but not the same as irony. With irony, there is some expectation that an action is being done in earnest with a goal in mind, but the opposite effect is achieved, against expectations. Hypocrisy is when someone says one thing, usually to look good, but really acts quite opposite. For example, a person who tells others to be faithful to their spouses, but has an affair. I'll say I often get hypocrisy and irony confused.

To be fair to my previous comment where a person says everyone should be open and honest, but hides behind an invented name---that's more hypocrisy than irony. Irony tends to be related to action and intent rather than in a statement of belief, though certainly it can be a statement. For someone to say something ironic is usually to have the other person knowingly understand that what is said and what is meant are opposites. Hypocrisy, on the other hand, is saying one thing, but not expecting the other person to find out, and not living up to what one says.

Ironically, being hypocritcal does not invalidate what is said. One can say that being faithful is good, and that advice can, in fact, be quite good, even as the the speaker is hypocritical. There is a sense, in hypocrisy, that the person says one thing and does another because they want to appear better than they are. It is certainly possible, however, for someone to give advice freely, while also admitting they themselves are too weak to follow it (eg, telling others smoking is bad, even as they themselves smoke).

With hypocrisy, there is a "holier than thou" attitude. You might say how it's awful that people can be so unclean, and yet be a complete slob. Implicit in hypocrisy is that the person knows that they are doing the opposite of what they advocate. If a person for example, deludes themselves into thinking they are neat (a slob's mess is always neater than a stranger's mess because they rationalize it to themselves that it's not that bad).