Question

By default the comments are shown by “social ranking”.

Is it possible to set the default value to “reverse chronological”?

The official docs for social plugins does not mention this option…

Answer 1

If you are using the social plugin given by FB, then i think there is no such option available..

what do u mean by Social ranking?

If you are ready to use FQL then you can try my below suggestion.

Normally all FB data are rendered based on timestamps , so if u want to get the latest comments for a specific page, you can use the FQL query to get desired results..

Sample query

http://www.facebook.com/restserver.php?format=json&pretty=1&method=fql.query&
query=select post_fbid, fromid, object_id, text, time from comment where
object_id in (select comments_fbid from link_stat where 
url ="http://developers.facebook.com/docs/reference/fql/comment/") 
order by time desc