Here's an example of my trying to work out the meaning of this passage:
What Paul is praying for the congregation of Philippi--that they will use knowledge and insight to determine what to do so they will ready for the day of Christ. Paul's criteria--they will have produced a harvest of righteousness. I have to pause--does Paul mean that being pure and blameless precedes or causes righteousness or does righteousness come through Jesus Christ's efforts or some combination?
I turn to the commentary. It doesn't answer those questions, but answers the questions I should have asked:
Having prayed for their love for each other to continue and to increase, Paul suggests that they still have something to learn. His hope is that they will continue to improve their knowledge and deepen their insight. Be tough-minded not naive. (Carl R. Holladay, Preaching through the Christian YearC