Which Thessalonian epistle came first?

Question

The text of Paul's letters to the Thessalonians does not identify one as "first" and the other as "second".

External evidence

None of the quotations of the epistles by the Apostolic Fathers identify "first" or "second":

• Ignatius probably quotes 1 Thess. in chapter 10 of his epistle to the Ephesians
• Polycarp quotes both epistles in chapter 11 of his epistle to the Philippians, but says nothing about their sequence

1 Thessalonians does appear after Colossians in the manuscript P46 (earliest surviving collection of Paul's epistles). This may be a good indicator, or it may not: Paul's epistles are not arranged in chronological sequence in P46 (or in any other manuscript), and the end of the manuscript (which presumably contained 2 Thess.) has been lost.

Internal evidence

The closest 2 Thess. comes to referencing a prior epistle is in chapter 2:

15 Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.

This could be, but is not necessarily a reference to 1 Thessalonians (see 2 Peter 3:1 for a clear example of referring to a prior epistle).

Which of the epistles was written first and how do we know?

Answer 1

Which Thessalonian epistle came first?

The posted question does find a key to determining a possible answer. In the topic "Thessalonians, Letters to the" in the Insight on the Scriptures, the subheading "Background for Second Thessalonians" continues the line of reason that was made in the posted question:

A problem that had already existed earlier in the congregation still needed attention. In his first letter to the Thessalonians, Paul had told them: “We exhort you, brothers, . . . to make it your aim to live quietly and to mind your own business and work with your hands, just as we ordered you; so that you may be walking decently as regards people outside and not be needing anything.” (1Th 4:10-12) There were those in the congregation who had not taken this admonition to heart. Hence Paul ordered such persons to work with quietness and eat food they had themselves earned, adding: “But if anyone is not obedient to our word through this letter, keep this one marked, stop associating with him, that he may become ashamed. And yet do not be considering him as an enemy, but continue admonishing him as a brother.”​—2Th 3:10-15.

So Paul, in the first epistle, addressed a problem that was taking place. He later, in the second epistle, mentions that same problem again because some had not heeded his counsel from his first epistle.

[All scripture quotations from the New World Translation of the Holy Scriptures (Study Edition)]