Presumably, the lights are there one per person seated below. Assuming each person needs at least 18" of
space between them and the next person, the free space 60 - 36 = 24". That split evenly would be 12".

E-- 12" --(L)--- 18" ---(L)--- 18" ---(L)-- 12" --E

where E is an edge, and L is a light.
Would that work for symmetry, usability and all ?
We have this spacing and it works for us.

/venkat

Where are your other lights in the kitchen?

Our seating is around one end of the island. We let our electric guy determine how best to light the entire kitchen 'space' and not worry about if the kids could see illuminated food or not.

Just make sure in lighting the island you don't end up with 'black holes'.

Wouldn't two be plenty for a 5 foot island??

It all depends on the size of the pendants. I have two pendants over my 7 foot island, but the pendants are ~8" in diameter. If I chose smaller ones, I would have wanted three of them.