This is one of my favourite idioms. I love playing devil’s advocate in my conversation classes.
What it means:
If you play devil’s advocate it means that you are giving arguments (that you don’t agree with) just for the sake of arguing. You are giving arguments that you don’t necessarily agree with to challenge the other person’s arguments.
When to use it:
I use it in my conversation classes during debates. Let’s say this is the topic of the debate: Women should stay at home.
I do NOT agree with that and because most of my students are women everybody disagrees with that statement too. It’s quite difficult to organise a debate when everybody agrees on the same topic.
That’s when I would take on the role of the devil’s advocate. I would throw arguments such as “women are better at taking care of children”, “who is going to clean the house then?” or “men earn more money anyway, so why should women bother working?”. Those arguments are obviously outrageously wrong. They go against what I think but it gets the debate going.
Use this idiom when talking with friends, when you are debating an interesting topic, if you want to challenge what your friend thinks and if his/her arguments are valid.
Now be careful who you play the devil’s advocate with… you could start a conversation you don’t want to finish!