A primary role of feedback design is to enable a system to cope with the inevitable uncertainly associated with its description. Although it is often the case that we have at hand a practical description of both the size and structure of the expected uncertainty, simple multivariable design strategies which effectively incorporate this information have been slow to appear. A rigorous development of the uncertainly problem for linear multivariable feedback systems is presented utilizing the characteristic locus framework, and then a simple geometric alignment property is exploited in order to formulate a systematic design strategy, focusing on a PI implementation for the resulting controllers