The paper proceeds from the basis that the dominant source of the geometry dependence of the effective tensile failure stress of an uncracked brittle structure is deterministic and is related to the formation of a damage zone at a free surface. The damage is represented by a cohesive zone, and failure, i. e. the attainment of maximum load, is associated with the attainment of an elastically calculated effective tensile failure stress. With regard to failure arising as a result of the formation of a damage zone at the surface of a blunt stress concentration, the paper predicts the extent to which the effective tensile failure stress increases with increasing severity of the stress concentration, i. e. as the root radius decreases.