Explanation
Indicates a parallel or matching situation; 'if Noun1 is (truly) Noun1, then Noun2 is also Noun2'.
Formation
Noun1 + が + (repeat Noun1) + なら、Noun2 + も + (repeat Noun2) + だ
Detailed explanation
This structure conveys a comparison: 'If Noun1 is indeed that kind of thing (Noun1), then naturally Noun2 is also that kind of thing (Noun2)'. It’s often used to show parallels or equivalences in a rhetorical way.
Examples
Oni ga oni nara, ningen mo ningen da.
If demons are indeed demons, humans are likewise humans.
Kare ga shachou nara, watashi mo shachou da.
If he is the president, then I'm the president too.
Kisama ga senshi nara, ore mo senshi da.
If you're a warrior, then I'm a warrior as well.
Hamusutā ga petto nara, neko mo petto da.
If a hamster counts as a pet, then a cat is also a pet.
Practice
Grammar content sourced from hanabira.org.