The Inherent Linearity of Impetus

  • Michael Elazar
Part of the Boston Studies in the Philosophy of Science book series (BSPS, volume 288)


This chapter discusses the inherent linearity of Fabri’s impetus, which entails specifically conservation of rectilinear motion rather than of both linear and circular motion (as, for example, Isaac Beeckman and Pierre Gassendi maintained). Fabri, following Descartes, employs the old scholastic notion of determinatio to describe the necessary basic linearity of impetus (and consequently motion): “an impetus”, he declares in De impetu, “must be determined (determinatus) along a certain line of motion”. Fabri’s use of the concept of determinatio, within his analysis of reflection from totally elastic planes, is subsequently described. Finally, Fabri’s view concerning circular motion is outlined: as a direct consequence of his (relatively) modern conception of motion as inherently linear, Fabri regards circular motion as arising from an impeded straight motion, and accordingly observes that a stone tied to a sling will proceed along a straight line tangential to the circular original trajectory if the rope suddenly breaks.


Incline Plane Circular Motion Elastic Plane Curve Motion Rectilinear Motion 
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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Max Planck Institute for the History of ScienceBerlinGermany

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