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Theoretical Entities / Sellars: are entities that are postulated along with certain principles. - To explain the regularities of perception.
Theoretical Entities / Sellars: you can not just take them as objects (particulars). - That depends more on the comment. - Impressions are th.e.. - They are predicates - E.g. molecules have mass, but "mass" is not an abbreviation of a description.
Der Empirismus und die Philosophie des Geistes Paderborn 1999