Posted on my site michel-foucault.com
We have to rid ourselves of the prejudice that a history without causality is no longer history.
[Michel Foucault. (1994) . Qui êtes-vous Professeur Foucault? In Dits et écrits: 1954-1988. Vol I. D. Defert, F. Ewald & J. Lagrange (Eds.). Paris: Gallimard, p. 607. This passage translated by Clare O’Farrell
Michel Foucault. (1999) . Who are you, Professor Foucault? In Religion and Culture. J. R. Carrette (Ed.). Manchester: Manchester University Press, p. 92.
Random thoughts in response
Foucault also remarks that if the linear succession of events is usually considered to be the matter of history, the analysis of how it is possible that two events can be contemporary with each other is less frequently regarded as history proper.
He made these comments in 1967 a year after the publication of The Order of Things. In this book Foucault looks at a number of simultaneous events or structures of knowledge and describes the similarity in structure between seemingly disparate fields of knowledge. The Order of Things was widely attacked by both Marxists and conservative critics for its unconventional views of history. Marxists saw Foucault’s non-linear approach to history as a conservative rejection of the inevitable historical process leading to revolution and the overthrow of capitalism.
Sartre who had become an enthusiastic Marxist fellow traveller after World War II claimed that in The Order of Things Foucault had replaced ‘cinema by the magic lantern, movement by a succession of immobilities’ adding that this rejection of history was ‘of course’ an attack on Marxism. What Foucault was really trying to do according to Sartre was erect a ‘new ideology, the last rampart that the bourgeoisie can still erect against Marx.’ 
In relation to causality, Foucault notes that in the natural sciences it has long been perceived that true causality is impossible to establish and that ‘basically causality doesn’t exist in logic’ (p. 607)
1. Jean-Paul Sartre. (1966, 15 October). Sartre répond, La Quinzaine Littéraire, p. 4.