" [Eventalisation] means making visible a singularity at places where there is a temptation to invoke a historical constant, an immediate anthropological trait or an obviousness that imposes itself uniformly on all. To show that things weren't 'necessary as all that'; it wasn't as a matter of course that mad people came to be regarded as mentally ill; it wasn't self-evident that the only thing to be done with a criminal was to lock them up; it wasn't self-evident that the causes of illness were to be sought through individual examination of bodies; and so on. A breach of self-evidence, of those self-evidences on which our knowledges, acquiescences and practices rest: this is the first theoretico-political function of eventalization. It means uncovering the procedure of causal multiplication: analysing an event according to the multiple processes that constitute it. As a way of lightening the weight of causality, 'eventalization' thus works by constructing around the singular event analysed as process a 'polygon' or rather a 'polyhedron' of intelligibility, the number of whose faces is not given in advance and can never properly be taken as finite. One has to proceed by progressive, necessarily incomplete saturation." Michel Foucault, 'Impossible Prison' in Foucault Live. 1996. p. 277

Against the accusation of working on a plane in between hyper and hypo rationalisms, Foucault replies that his historical method aims at going against the de-eventalization that has occurred in historical analysis, broadly speaking the ascribing of unitary character to the object analysed (whether anthropologically, economically, or demographically). The work of multiple causation and polyhedric intelligibility might be regarded as too much or too little but it aims at being just that: a plethora of intelligibilities and a deficit of necessities.
'This is precisely the point at issue, both in historical analysis and political critique. We aren't nor do we have to put ourselves under the sign of a unitary necessity.'