The paper proceeds from the basis that the dominant source of the maximum load size effect for uncracked brittle structures is deterministic, and is related to the formation of a damage (fracture process) zone at a free surface. By modelling this damage behaviour in terms of the cohesive zone description, and by associating the maximum load with the attainment of an elastically calculated effective tensile failure stress, the paper projects the view that the effective stress is critically dependent on the applied loading induced stress gradient beneath the surface of a structure. The effective tensile failure stress increases with the steepness of the stress gradient, and we therefore have a ready explanation as to why the effective tensile failure stress for an uncracked bend beam increses as the beam depth decreases.