ABSTRACT
As Gibson has pointed out, Locke ‘does not follow Descartes in proclaiming a priori the universal applicability of the mathematical method. The negligence or perverseness of mankind cannot be excused, if their discourses in morality be not much more clear than those in natural philosophy: since they are about ideas in the mind, which are none of them false or disproportionate; they having no external beings for archetypes which they are referred to and must correspond with. There are, Locke thinks, two reasons why the ideas of quantity have in the past been considered more capable of demonstration than those of morality. Diagrams drawn on paper are copies of the ideas in the mind, and not liable to the uncertainty that words carry in their signification. The desire for happiness and aversion to misery are admittedly ‘innate practical principles’ of a sort; but they are, Locke says, ‘inclinations of the appetite to good, not impressions of truth on the understanding’.
