"For All We Know" is a soft rock song written for the 1970 film Lovers and Other Strangers, with music by Fred Karlin and lyrics by Robb Wilson (Robb Royer) and Arthur James (Jimmy Griffin). Both Royer and Griffin were founding members of the soft-rock group Bread. It was originally performed by Larry Meredith. It is best known for a cover version by American pop duo Carpenters in 1971, which reached No. 3 on the US Billboard Hot 100 singles chart and No. 1 on the US Billboard Easy Listening chart. The song was also a hit for Shirley Bassey at the same time in the United Kingdom. It has since been covered by a large number of artists.

The song became a Gold record. It won the Academy Award for Best Original Song in 1971.

Richard Carpenter of Carpenters heard the song during an evening of relaxation at the movies while on tour. He decided it would be ideal for the duo. It became a hit for them in 1971, reaching number three on the Billboard Hot 100 singles chart and number one for three weeks on the US easy listening chart.

When the original song was nominated for an Academy Award, the Carpenters were not allowed to perform it at the ceremony as they had not appeared in a film. At their request, the song was performed by British singer Petula Clark. (Clark would later perform the song in concert on February 6, 1983, in tribute to Karen Carpenter, who had died two days before.)

According to Richard, the English horn intro was originally played on guitar. They had run into Jose Feliciano in a restaurant, who was a big fan of theirs and wanted to play on one of their records. They went into the studio and the intro was devised by Feliciano, using his nylon string acoustic guitar. The next day, though, Richard got a phone call from Feliciano's manager, demanding that he be removed from the recording. Richard essentially did as requested and replaced Feliciano's guitar intro with that of Earle Dumler's oboe. The other instruments heard on the song were recorded by session musicians later known as the Wrecking Crew.

...
Wikipedia