The Pauline epistles are the thirteen books in the New Testament traditionally attributed to Paul the Apostle. There is nearly universal consensus in modern New Testament scholarship on a core group of authentic Pauline epistles whose authorship is rarely contested: Romans, 1 and 2 Corinthians, Galatians, Philippians, 1 Thessalonians, and Philemon. Several additional letters bearing Paul's name are disputed among scholars, namely Ephesians, Colossians, 2 Thessalonians, 1 and 2 Timothy, and Titus. Scholarly opinion is sharply divided on whether or not Colossians and 2 Thessalonians are genuine letters of Paul. The remaining four contested epistles – Ephesians, as well as the three known as the Pastoral epistles (1 and 2 Timothy, and Titus) – have been labeled pseudepigraphical works by most critical scholars. Some scholars have proposed that Paul may have used an amanuensis, or secretary, in writing the disputed letters, although such a solution would not explain the fact that the disputed letters appear to have been written at least a decade after Paul’s death. There are two examples of pseudonymous letters written in Paul's name apart from the New Testament epistles, the Epistle to the Laodiceans and 3 Corinthians. The Epistle to the Hebrews is actually anonymous, but it has been traditionally attributed to Paul. The church father Origen of Alexandria rejected the Pauline authorship of Hebrews, instead asserting that, although the ideas expressed in the letter were genuinely Pauline, the letter itself had actually been written by someone else. Most modern scholars generally agree that Hebrews was not written by the apostle Paul. Various other possible authorships have been suggested. Criteria used by scholars Scholars use a number of methods of historiography and higher criticism to determine whether a text is properly attributed to its author. The primary methods used for Paul's letters are the following: Internal evidence Internal evidence consists of what the author states about themself in the letter, either explicitly the author clearly identifies themself or implicitly provides autobiographical details. This evidence is important in spite of its problems. For example, because the author of the Epistle to the Hebrews never identified themself, scholars as early as Origen of Alexandria in the 3rd century suspected that Paul was not the author. External evidence This consists of references, again either explicit or implicit, to the text, especially during earliest times by those who had access to reliable sources now lost. Explicit references would be mentioning