Methods & Evidence in History (DP IB Theory of Knowledge): Revision Note

Methods & evidence in history

• Historical knowledge production uses methods for selecting, evaluating and interpreting sources to justify claims about past events

• Evidence in history is rarely complete or neutral, so historians use checks like source analysis and corroboration to reduce error and bias

• Sometimes, an overwhelming amount of evidence is available, and historians can produce historical facts rather than claims

• Sometimes new evidence is uncovered, and previous historical knowledge has to be revised

Primary vs secondary sources

• A primary source is produced at the time of the events being studied or by someone directly involved, while a secondary source is a later interpretation that analyses primary material

  • Primary sources can provide direct traces of beliefs and actions, but still need interpretation

  • Secondary sources can synthesise multiple sources and offer a view of the wider context, but their conclusions depend on the selection and reading of primary evidence

• Neither type is automatically more trustworthy

  • A primary source can be biased or incomplete, and a secondary source can be careful and well-evidenced, so reliability must be argued rather than assumed

Source analysis: Reliability, usefulness and bias

• Source analysis is the method of evaluating what a source can and cannot justify by checking features such as:

  • who produced it

  • why it was produced

  • for whom it was produced 

  • its date of production

• Historians must then consider how these features affect reliability, usefulness, and bias

  • Reliability: how dependable a source is as evidence for a specific claim

    • Reliability is higher when a source is close to the events, has access to first-hand information and has fewer incentives to distort what it reports

  • Usefulness: how well a source helps answer the guiding question

    • Usefulness is higher when a source contains specific details that can support or challenge a claim

  • Bias: a systematic tendency to present information in a particular way due to interests, values or constraints

    • Bias is stronger when the source is produced to persuade, justify or protect interests, so it systematically selects, frames or omits information in one direction

    • Bias does not automatically make a source false, but it affects what can be justified from it

Comparing accounts & corroboration

• Comparing accounts is placing two or more accounts side-by-side to identify similarities and differences in what they claim

• Corroboration happens when an independent source supports the same specific claim as another source

  • Corroboration is stronger when the sources are independent rather than linked, e.g. two eyewitness letters can corroborate a detail more strongly than two newspapers repeating the same official statement

• Corroborating accounts matter because independent agreement makes a claim easier to justify, reducing the risk that it rests on one person’s mistake, limited viewpoint or self-interest

• Differences between accounts are also useful; they may reveal what a single source might be missing, exaggerating or framing in a particular way

  • E.g. if an official report and a personal letter describe the same event differently, the contrast can show the report’s public aims and the letter’s lived impact

Gaps, silences and missing evidence

• Gaps and silences occur when evidence is lost, was never created or has been excluded from the record, limiting what can be justified

• Missing evidence can distort knowledge by overrepresenting groups who had the power or opportunity to leave records

  • E.g. if only official documents survive, everyday experiences may be treated as less significant because they are less visible

• Historians should avoid turning the absence of evidence into evidence of absence without justification

  • a lack of records may mean an event was not recorded, not that it did not happen

• Responsible historical claims are clear about the existence of uncertainty and stay proportional to the evidence available