In this article, we analyse the modal forms sans doute and sin duda. Despite their formal similarity, they do not always represent the same degree of certainty in French and Spanish. After a detailed analysis of their use in both languages, our conclusions show that sans doute is a probability marker, whereas sin duda is an (almost) certainty marker. After examining the relationship of these modal markers with evidentiality, we underscore the epistemic character of both markers; they are related to belief and subjectivity, thus the nature of certainty that they express is indirect and subjective. Sin duda manifests a higher degree of conviction than sans doute.

This study was undertaken within the framework of a research project funded by the Spanish Ministry of Science and Innovation (FFI2011-25755: Modalidad epistémica, evidencialiad y gramaticalidad: análisis contrastivo inter e intralingüístico en el discurso oral y escrito).