1. used to provide a noted reason for doing something
for the sake of argument/discussion/expediency
If you do something for the sake of something you do it for that purpose or out of consideration for a specific person. To do something for someone's sake or for your own sake means to do something for someone else's advantage or with a specific motive in mind. The expression for God's sake or for Pete's sake are exclamations of anger or surprise and are much more informal and used in social contexts.