The use of evidential and epistemic marking as a rhetorical strategy has received little attention in the literature. Speakers often make judgments on the basis of perceptual, reported, or inferred evidence, thus the relationship between epistemicity and evidentiality is often close and difficult to demarcate. However, whereas epistemicity involves the speaker's or writer's evaluation, judgment and degree of commitment attached to the truth-value of a piece of information, evidentiality involves the speaker's or writer's assertion of the source and kind of evidence at their disposal (De Haan, 2001, 2005; Mushin, 2001; Nuyts, 2005). Both of these semantic notions have been thoroughly dealt with in regard to morphosyntactic, lexical and grammatical marking, but relatively little has been investigated in pragmatic and textual terms. The present study approaches the indexing of epistemicity and evidentiality from the point of view of register by analyzing a total of 30 oral and 30 written productions of two opinion reports (one dealing with a debatable issue and the other with a non-debatable issue) produced by 15 Catalan speakers. The main aim of the paper is to test the potential effects of register (i.e., oral vs. written discourse) and debatability (i.e., debatable vs. nondebatable issue) on the discourse marking of evidentiality and epistemicity. With respect to the effects of register, results confirm that the use of both epistemic and evidential markers is significantly higher in the oral than in the written reports, and specifically the use of low certainty epistemic markers and direct evidential markers. With respect to the effects of debatability, results show that there is a more profuse use of epistemics than evidentials in the debatable than in the nondebatable condition, and specifically the use of low certainty markers and common knowledge and reported evidential markers. In general, these results support the view that register and debatability are two important factors that condition the use of evidentiality and epistemicity in the construction of discourse epistemic stance.

A preliminary version of this paper was presented at the conferences The Nature of Evidentiality 2012 (Leiden, June 13-15, 2012), and Modality, Corpus, Discourse (Lund, June 7-8, 2012). We would like to thank participants at those meetings, especially Johan Rooryk, Monica Lau, Margaret Speas, Carita Paradis and Jan Nuyts, for their helpful comments. We also acknowledge the technical assistance given by Maria Dolors Cañada at the Universitat Pompeu Fabra in the Atlas.ti. procedure to analyze our data. This research has been supported by the Spanish Ministerio de Ciencia e Innovación (MICINN; research grants FFI2011-25755 and FFI2009-07648) as part of the project ‘‘Epistemic modality, evidentiality and grammaticality. Inter- and intralinguistic contrastive analysis in oral and written discourse [MODEVIG]’’ and by a grant awarded by the Generalitat de Catalunya to the Grup d’Estudis de Prosòdia (2009SGR-701).