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Confirmatory Evidence

Definition

Evidence that increases the probability of a hypothesis already suggested by other means. In UNABOM, the linguistic analysis served this role: it made the case against Kaczynski stronger once he was identified, but did not generate the identification itself.

Function
Strengthens an existing hypothesis
Does not do
Generate the original identification
Case example
UNABOM stylometric analysis of Kaczynski
Related domain
Forensic linguistics, stylometry

Common questions

Why is confirmatory evidence not sufficient on its own to identify a suspect?+

It is defined by increasing the probability of a hypothesis that already exists from other sources, so it needs that prior hypothesis to act on. Without an initial suspect, there is nothing for the confirmatory analysis to strengthen.

How did stylometric analysis function in the Unabomber case specifically?+

Investigators compared the language and phrasing of the manifesto against writing samples from Theodore Kaczynski after family members raised him as a suspect. The linguistic match reinforced the case against an already-identified individual rather than pointing investigators to him in the first place.

Related terms

Authorial Profiling
The production of demographic and psychological inferences from a text's language, as opposed to attribution, which names a specific author. The UNABOM...
FBI Linguistic Analysis Unit (LAU)
The FBI division responsible for linguistic profiling, author identification, and threat assessment. The LAU produced the authorial profile used in the UNABOM...
Idiolectal Feature
A linguistic habit characteristic of one specific person rather than a group. In the Unabomber case, phrase patterns such as 'feelings of...
UNABOM
The FBI case designation for the Unabomber investigation (Universities and Airlines BOMbing). The case ran from 1978 to 1996 and is one...

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