 What does the sense-datum theorist say at Level 1? On this theory, whenever a subject has a sensory experience, there is something which is presented to them. This relational conception of experience is sometimes called an “act-object” conception, since it posits a distinction between the mental act of being presented with something, and the object presented. More precisely, the sense-datum theorist holds that an experience in which something appears F to S, where F is a sensible quality (e.g., whiteness), consists in S being directly presented with something which actually is F (e.g. a white thing). They thus endorse the aforementioned Phenomenal Principle. The sense-datum theorist calls these objects of perception “sense-data”.