This book analyses the concept of scientific explanation developed by French disciples of Descartes in the period 1660-1700. Clarke examines the views of authors such as Malebranche and Rohault, as well as those of less well-known authors such as Cordemoy, Gadroys, Poisson and Régis. These Cartesian natural philosophers developed an understanding of scientific explanation as necessarily hypothetical, and, while they contributed little to new scientific discoveries, they made a lasting contribution to our concept of explanation--generations of scientists in subsequent centuries followed their lead.