"To play devil's advocate" means to support an opposing viewpoint in an argument for the sake of the argument. (So that other sides of the argument are heard and a more rounded conclusion can be made). Example: Tom: I think it is a good idea to have free college education in this country so that our population can better educate themselves. Bob: Well, I am going to play devil's advocate and say that free education is a bad idea. Think of the cost of providing such a service. Let me know if this makes sense or not. Feel free to ask me for help anytime.

Cultural note: the phrase comes historically from the Catholic Church and canonization, the process of declaring someone to be a saint. A saint is someone with a special holy status. The church recently declared Mother Teresa to be a saint. The procedure for declaring someone a saint is "canonization." It includes a trial that resembles a legal trial. One of the requirements for being a saint is that the saint must have performed miracles. In the trial, the evidence for the miracle is judged. An "advocate" is a lawyer. The "Devil's advocate" is someone who has the job of giving reasons why the person should _not_ be canonized. For example, he would argue that the miracles weren't proven. (In modern times, many of us are less likely to believe in physical miracles. This requirement for sainthood is more difficult than in the past. Mother Teresa was said to have been involved in two "medically inexplicable" miraculous cures of diseases). As with real lawyers, the Devil's advocate probably believes that the person should be declared a saint, and is just doing the job that's assigned. Informally, that's what the phrase means. "Let me be devil's advocate" means "Please forgive me, I don't believe this, but to protect ourselves let's consider the opposite side." As an example of use, "There would be less furor surrounding that government policy if only the leader had had a devil's advocate to point out the potential practical issues and legal problems in it."

It means to test the strength of an argument (or belief, or position, or policy) by putting forward an opposing one, usually when you don't actually believe what you're saying yourself. It's another way of saying "for the sake of argument" (i.e. not because I believe this, but just to see how you respond to this argument). For example "I agree that it's a good idea to make drugs illegal. But just to play devil's advocate, wouldn't doing so put people out of work and ruin other people's fun?"

We can this phase discussions which may be daily or formal conversation.Anybody who joined conversation tells about negative aspects of conversation subject. That's what I heard.i hope i could help.