Evidence Standards

Primary vs. secondary sources

A primary source is direct physical or textual evidence surviving from, or close to, the period under discussion: a manuscript, a monumental or numismatic inscription, a papyrus document, an archaeological find, a dated coin, or an early text transmitted from the period it describes. The Evidence Library catalogs primary sources by category (manuscripts, inscriptions, coins, papyri, archaeology, and more), and every entry marked as a primary source is labeled as such in its record.

A secondary source is scholarship that analyzes, interprets, or contextualizes primary evidence: a peer-reviewed journal article, an academic monograph, a doctoral thesis, or a scholarly edition of a primary text. Our full bibliography of secondary scholarship is listed on the Academic Sources page.

The distinction matters because the two carry different kinds of authority. A primary source tells you what physically survives; a secondary source tells you how a specialist has interpreted it. Research papers on this site are expected to engage the primary evidence directly wherever it is accessible, rather than relying solely on secondary description of it.

Levels of historical confidence

Not every historical claim carries the same weight of evidence, and papers on this site say which level applies rather than presenting every claim with the same tone of certainty. Where relevant, the concluding section of a paper states plainly what the evidence does and does not establish, using distinctions of this kind:

Well-attested

Supported by more than one independent primary source (for example, a text corroborated by an inscription or archaeological find) and reflects a broad, current scholarly consensus.

Probable

Supported by credible primary or secondary evidence and the majority of specialist opinion, but with an open question, a dating uncertainty, or a minority scholarly dissent worth naming.

Contested

Specialists actively disagree, and the primary evidence itself can reasonably support more than one reading. Both readings are presented rather than one being treated as default.

Speculative

A plausible reading that goes beyond what the current evidence can independently establish. Flagged as such rather than stated as fact.

These levels are expressed in the prose of each publication, in context, rather than as an isolated label, because historical confidence is a judgment about a specific claim and its specific evidence, not a property of a source in the abstract. The same primary source can support a well-attested reading on one point and only a speculative one on another.

Citation policy

Every substantive factual or historical claim in a research paper or article is tied to a specific reference. References are authored once per publication and cited inline wherever they support a claim; each in-text citation links directly to its full entry in that publication's reference list, and every reference in turn contributes to the site-wide Academic Sources bibliography, so a source cited once can be traced across every publication that relies on it.

Research papers are formatted in either Chicago or APA style, stated on the paper itself, and interpretive or contextual asides that are not direct citations are set apart as footnotes rather than mixed into the numbered reference list. Where a primary source discussed in a paper also has its own Evidence Library entry, the paper links to it directly, so a reader can move from an in-text claim to the underlying evidence in one step.

Related standards

For the process a publication goes through before these standards are applied, see Methodology. For the editorial rules governing neutrality and what we will not publish, see Editorial Principles.