We Can Work It Out (Number One 50 years ago) Behind the song.......
McCartney wrote the words and music to the verses and the chorus, with lyrics that "might have been personal", probably a reference to his relationship with Jane Asher. McCartney then took the song to Lennon:
I took it to John to finish it off, and we wrote the middle together. Which is nice: 'Life is very short. There's no time for fussing and fighting, my friend.' Then it was George Harrison's idea to put the middle into 3/4 time, like a German waltz. That came on the session, it was one of the cases of the arrangement being done on the session.
With its intimations of mortality, Lennon's contribution to the twelve-bar bridge contrasts typically with what Lennon saw as McCartney's cajoling optimism,a contrast also seen in other collaborations by the pair, such as "Getting Better" and "I've Got a Feeling". As Lennon told "Playboy" in 1980:
In We Can Work It Out, Paul did the first half, I did the middle eight. But you've got Paul writing, 'We can work it out / We can work it out'—real optimistic, y'know, and me, impatient: 'Life is very short, and there's no time / For fussing and fighting, my friend.'
Based on those comments, some critics overemphasized McCartney's optimism, neglecting the toughness in passages written by McCartney,such as "Do I have to keep on talking until I can't go on?". Lennon's middle shifts focus from McCartney's concrete reality to a philosophical perspective in B minor, illustrating this with the waltz-time section suggested by George Harrison that leads back to the verse,possibly meant to suggest tiresome struggle.