We prove a quantitative version of the Gibbard-Satterthwaite theorem. We show that a uniformly chosen voter profile for a neutral social choice function f of q ≥ 4 alternatives and n voters will be manipulable with probability at least 10 −4 ǫ 2 n −3 q −30 , where ǫ is the minimal statistical distance between f and the family of dictator functions.Our results extend those of [FKN09], which were obtained for the case of 3 alternatives, and imply that the approach of masking manipulations behind computational hardness (as considered in [BO91, CS03, EL05, PR06, CS06]) cannot hide manipulations completely.Our proof is geometric. More specifically it extends the method of canonical paths to show that the measure of the profiles that lie on the interface of 3 or more outcomes is large. To the best of our knowledge our result is the first isoperimetric result to establish interface of more than two bodies.