Abstract
The subject of vagueness is discussed in analytical philosophy but from a linguistic point of view it is rather overlooked. We approached the issue of the concept definition and tried to find the cross point of two fields which is found in approach to vagueness using or violating of cooperative principle. The aim of the paper is to specify the criteria for the evaluation of vagueness, determine the motivation to use vagueness, defining its potential sources and describing the language means that typically make vagueness in persuasive texts specifically in politically oriented speeches. Based on the results of qualitative analysis, the occurrences of vagueness were found at lexical units’ level and semantic-pragmatic units. We have therefore focused on the linguistic manifestations of vagueness that is the appearance of evaluative adjectives, epistemic particles, metaphors, abstract word etc. Quantitative analysis of these linguistic categories has proven to be inadequate because not all of these occurrences can be labelled as vague. For this reason, we have been applied four types of vagueness based on violation of conversational maxima, which offers and partly clarifies conceptual difficulties and provide instructions for detecting vagueness in the text.