The logic (so to speak) in the article boils down to:
1. We know how to identify interpolations, e.g. these texts.
2. We haven't identified interpolations in Paul's letters.
3. Therefore, Paul's letters contain interpolations.
1. We know how to identify interpolations, e.g. these texts.
2. We haven't identified interpolations in Paul's letters.
3. Therefore, Paul's letters contain interpolations.