One of the best ways of doing this is to rework old discussions (cf WhatIsReworking). If you see an old fossilised argument, delete everything that no longer has value (if indeed it ever had value), and leave a summary of what's been learnt.
However, you can't force forgiveness on the community against its will. If you've been heavily criticised on some page, leave it to someone else to decide that it's no longer relevant (though you may want to prod them a bit).
This applies even to CommunityExiles - the community must learn to forgive and forget their crimes.
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