An exercise we ran at minicamp -- which seemed valuable, but requires a partner -- is to take and argue for a position for some time. Then, at some interval, you switch and argue against the position (while your partner defends). I used this once at work, but haven't had a chance since. The suggestion to swap sides mid argument surprised the two, but did lead to a more effective discussion.

The exercise sometimes felt forced if the topic was artificial and veered too far off course, or if one side was simply convinced and felt that further artificial defense was unproductive.

Still, it's a riff on this theme.