 All these philosophers assumed that the visual and tactual sensations of an object differ from each other, but there was no agreement concerning the relation between the two. Some, Berkeley for instance, believed that this relation is arbitrary and based only on experience. Others, such as Lee and Synge, thought that it is necessary and perceived directly, while yet others, such as Molyneux and Locke, thought that it is necessary and learned by experience. Opinions were also divided concerning the relation between visual and tactual notions of objects. Some philosophers defended the position that the visual and tactual notions of a globe differ from one another, and can only be related by either experience or reason (the latter view was defended by Reid). Others believed that the visual and the tactual notion of a globe are actually the same, or have something in common which is either observed directly (Boullier and Hutcheson) or inferred by reason (Leibniz).