The best way to explain the Jeremiad form of rhetoric is to think of it in terms of the origins of the name. Jeremiah was a Biblical prophet of doom and, as one of my professors so astutely put it, a performance artist. The Jeremiad, then, is really a political sermon, and is applied by powerful leaders in front of large audiences. Predicting misfortune is a way to frighten the audience---or society---into believing whatever the rhetorician wants them to believe.
Jeremiad as a rhetorical device
The Jeremiad is specifically a form of epideictic rhetoric. Epideictic rhetoric refers to a lamentation (or, interestingly enough, celebration). It is the rhetoric of display and even social control: "the epideictic speech builds and creates a community for both speaker and audience, particularly... in times of crisis that threaten the society" (A Time of Shame and Sorrow, Murphy 271). This is arranged from combining the talk of doom with a hopeful word of what could happen if we only do as we are told.
Although the Jeremiad speaks to an audience and is bent upon social control, the way that it achieves this is through a divide-and-conquer method. Politicians such as George Bush who use the Jeremiad throughout their term point to the individual as being responsible for dealing with the crisis.
The idea is that the person = the nation, and it is because of this basic premise that the politician is able to get away with saying that our individual sins are the problem. The system itself is assumed to not have any flaws at all, and it is therefore up to individual citizens to make changes. Only from there will the situation improve.
There are three parts to the structure of the Jeremiad:
1. It refers to either biblical or spiritual teaching (for example, with George Bush the spiritual teaching would be the American Dream or the American forefathers).
2. It demonstrates how the community has failed to live up to that teaching.
3. It suggests the idealistic place that we would be in if we repent and reform.
All of this results in uniting people together, making it perfect for political campaigns. The politician using the Jeremiad as their form of rhetoric convinces the people that our society is in a terrible state, and then the politician explains why they are the one person who has the solution to the problem. If they know how to wisely make use of the Jeremiad, it isn't too difficult from there to get the votes they need.
The Jeremiad is an effective choice for politicians but can, for obvious reasons, be rather tiresome if you choose to use it on a daily basis. You're better off leaving it for situations in which you are speaking to a large audience where people will more likely give in to group-think; using the Jeremiad in a one-on-one situation, though it could make for an amusing psychology experiment, will probably result in the other person backing slowly away from you.