Thank you for subscribing to Annotated Thomist...check back each day for a new section of St. Thomas' corpus, annotated and summarized. (FREE TRIAL FOR NEW SUBSCRIBERS!!!)
AT is also available to donors of $10 or more on Patreon or SubscribeStar along with all of the other benefits (daily bonus videos, bonus articles, PDFs, etc.)
If you need more personalized help reading the Summa, I am available for 1-on-1 sessions, here.
Collect: O God who brings about justification in us unto the remission of sins, infuse grace in us that we may detest sin and may love justice, through Christ our Lord. Amen.
Summary
In the Sed Contra, St. Thomas points to the fact that in order to explain what is necessary for a thing, we ought to explain its causes. Now, the final cause of justification is the remission of sins. Therefore, it ought to be reckoned as necessary.