Explaining the seven types of historical evidence

These words describe different qualities or problems that historical evidence can have.

Clear evidence

Evidence whose meaning is relatively straightforward.

Example:

The text of the Thirteenth Amendment explicitly abolished slavery.

There is little ambiguity about what the constitutional text says.

Strong evidence

Evidence that provides substantial support for a claim.

Example:

Multiple land records, census data, and historians demonstrate severe disparities in land ownership after emancipation.

Weak evidence

Evidence that provides only limited support.

Example:

One person's recollection suggests that former slaves were economically dependent.

One recollection alone may not establish a general pattern.

Ambiguous evidence

Evidence that can reasonably be interpreted in more than one way.

Example:

A historical document says a worker was “free,” but it is unclear whether “free” means legally free, economically independent, or simply not enslaved.

Incomplete evidence

Evidence where important information is missing.

Example:

We have land records for some counties but not enough records for the entire South.

Contradictory evidence

Different pieces of evidence point in different directions.

Example:

One source says a particular group obtained substantial land, while another dataset suggests land ownership remained very limited.

The researcher then has to investigate why the sources differ.

Disputed evidence

Evidence whose interpretation or reliability is contested among historians.

Example:

Historians disagree about how extensively a particular federal land policy actually benefited formerly enslaved people.

These categories can overlap.

For example, evidence can be strong but incomplete.

That is an important point in historical research.