 Now consider the same motive not with respect to its rational authority but with regard to its psychological strength. Is this motive the strongest of your motives? Reid maintains that this is a difficult question to answer. One of the complaints Reid raises about the System of Necessity is that it sheds no light on the matter. Although advocates of the System of Necessity claim that human actions can be subsumed under natural laws, the laws to which they appeal in order to assess the strength of motives are either false or trivial. For recall that, according to the System of Necessity: