On second thought; from a different, conflicting, or contradictory point of view. This deal could really help the business get out of debt. Then again, you'd just be indebted to the government instead, so maybe it's not the best solution. I'd love to upgrade our car. Then again, there are lots of other things around the house that we need to replace more urgently.
Also, but then. On the other hand, an opposite possibility. For example, I think it'll arrive tomorrow; then again, it may not, or We think you'll like this restaurant, but then again, not everyone does, or The play was a bit dull, but then she's a great actress.
then/there aˈgain(informal) used for introducing an extra piece of information which explains something or gives another explanation for something: I thought he liked me, but then again maybe he didn’t.
From another standpoint; on the other hand: I need a vacation. Then again, so do my coworkers.