 In the above statement of the Classical Notion, nothing explicit is said about the metaphysical classification of sense data. They might be events, substances, states of substances; they might be either physical or mental. As mentioned, the majority of authors involved in the original discussion held that sense data are not mental. But some theorists advised that the term “sense data” in its basic meaning should be treated as neutral on ontology (e.g., Moore 1913–14; Price 1932: 18–20), even if further argument led to a view that they are not mental. For the neutralists, accepting that sense data exist should be compatible with various theories of perceptual ontology, such as naïve realism, representative realism, Berkeleyan idealism, and Kantian transcendental idealism.