German wohl 'well', Norwegian vel 'well' and French bien 'well' are all known to have a modal particle reading that roughly amounts to 'surely, probably, I guess' (see Zimmermann 2008, Fretheim 1991, Detges & Waltereit 2009. This paper addresses the question of how such a reading could have arisen from the source meaning of these elements (i.e. 'well'). I propose an analysis of wohl-type (i.e. 'well'-type) modal particles as scalar operators, which is based on the observation that each of them appears to have diachronically gone through an intermediate stage in which it was clearly a scalar modifier (namely wohl 'approximately', vel 'approximately, more than', and bien 'very'). The core idea of my contribution is that the modal particle variant is still a scalar operator in nature, but has emerged through a shift in the type of scale that the particle operates on (in line with Beltrama's 2015 approach to English totally). Scalarity thus emerges as a common meaning atom (or meaning molecule), in the spirit of von Fintel & Matthewson (2008:154,172), which serves as a building block in the semantic makeup of wohl-type particles.