The formulation of sound strategy may often be a rational process, but it is complicated by several polar tensions or contradictions. In What Good is Grand Strategy?, Hal Brands stressed how strategists seek clear logic but have to deal with the reality of nonlinearity and the pervasiveness of uncertainty in human affairs. Policymakers want to obtain foresight years into the future forces but must accept that the future is not foreseeable due to irreducible uncertainty in the world. Senior leaders might desire a tightly disciplined use of resources, but also need flexibility and reserves to adapt to changed and emergent circumstances. Great leaders must be decisive, but they must also seek consensus and compromise.