 This is not a problem that Condillac rectified in the Treatise. Instead, he attempted to side-step it by focusing just on the question of how experience leads us to form the idea that there are extended, external objects that bear the qualities of colour, taste, and smell exhibited in our sensations, while eschewing any over-confident metaphysical claims about the extent to which this idea may be correct. Indeed, towards close of the Treatise he admitted that the question of whether material things exist is not one that we are in any position to answer. We cannot be sure that objects are extended, shaped, and mobile, yet colourless, odourless, and tasteless. For all we know the objects that cause our sensations may not only be extended and solid, but endowed with qualities that resemble our sensations of smell, taste, and colour. Or they may be not only colourless, odourless, and tasteless but unextended (Treatise IV.v).