incoherence

Incoherence, in general, is the absence or breakdown of coherence, the property of being logically connected, consistent, or unified. The term is used across disciplines to signal a lack of ordered relation among parts of a system, statement, or signal.

In logic and argumentation, incoherence describes reasoning that is internally inconsistent or fails to follow from premises to conclusions, including non sequiturs and contradictions, leading to a failure to establish a credible claim.

In linguistics and discourse analysis, incoherence refers to discourse that lacks clear structure, continuity, or referent resolution—such as abrupt topic shifts, unclear antecedents, or missing transitions that impede understanding.

In physics and signal processing, coherence describes a fixed phase or predictable relationship between waves or signals; incoherence arises when phases are random or rapidly varying. Incoherent light, for example, lacks a stable phase relation, reducing interference effects. Measures include coherence length and coherence time.

In psychology and psychiatry, incoherence can describe disorganized or illogical speech or thought patterns, as seen in certain mental states or illnesses. Clinicians examine overall symptom patterns and context to determine significance.

In everyday use, writers or speakers aim for coherence; lack thereof may result from poor organization, ambiguous cues, or insufficient background information.

Etymology: from Latin cohaerent-, cohaerere to cling together; the prefix in- yields the sense of negation. Related terms: coherence, coherent.