 (1) massive loss: the magnitude of the possible losses is massive; (2) threshold likelihood: the likelihood of the losses is significant, even if no precise probability can be specified, because (a) the mechanism by which the losses would occur is well understood, and (b) the conditions for the functioning of the mechanism are accumulating; and (3) non-excessive costs: the costs of prevention are not excessive (a) in light of the magnitude of the possible losses and (b) even considering the other important demands on our resources. (Shue 2014: 265; footnote omitted) 