By Jacob P. Murre

The speculation of causes used to be created by means of Grothendieck within the Nineteen Sixties as he looked for a common cohomology idea for algebraic types. the speculation of natural reasons is definitely validated so far as the development is worried. natural reasons are anticipated to have a couple of extra houses anticipated via Grothendieck's common conjectures, yet those conjectures stay broad open. the idea for combined reasons remains to be incomplete. This booklet bargains essentially with the idea of natural reasons. The exposition starts with the basics: Grothendieck's building of the class of natural explanations and examples. subsequent, the normal conjectures and the recognized theorem of Jannsen at the classification of the numerical reasons are mentioned. Following this, the $64000 conception of finite dimensionality is roofed. the concept that of Chow-Künneth decomposition is brought, with dialogue of the identified effects and the similar conjectures, specifically the conjectures of Bloch-Beilinson kind. We end with a bankruptcy on relative causes and a bankruptcy giving a quick creation to Voevodsky's concept of combined causes.