 As so much of the debate concerning others in the heyday of its discussion in analytic philosophy in the twentieth century can be read as a reaction to Mill’s formulation of the argument from analogy, it is instructive to consider the context for Mill’s work  here.[16]  In proposing his argument, Mill was responding to a challenge laid down by the eighteenth century philosopher Thomas Reid who argued that Descartes’ philosophy, when traced through the work of philosophers such as Malebranche, Locke, Hume and Berkeley, leads to solipsism. In order to avoid this conclusion, Reid argued that philosophers must jettison the Cartesian framework of ideas and its trust in reason over the deliverances of sense. According to Reid, the faculties of reason and perception should be regarded as being on an equal footing. Rather than insist that all human belief is regulated by reason, Reid holds that we should allow that our perceptions of the world are guided by principles for which no proof can be offered. Amongst the regulative principles Reid identifies there are two concerning others: (i) there is life and intelligence in our fellow men; and (ii) certain features of the countenance, sounds of the voice and gestures of the body indicate certain thoughts and dispositions of mind (Reid 1785). Mill’s work is designed as a defense of the Cartesian framework in response to Reid’s claim that it leads inexorably to solipsism. According to Mill, all truths are known in one of two ways: either directly, through the authority of consciousness, or indirectly, by inference from truths known directly. Mill believes that knowledge arrived indirectly in this way is sufficient to avoid the concern of solipsism.