then again - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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.