  On Lewis’s view, believing is self-ascribing. Agents self-ascribe properties, so the things they believe are properties. If John sincerely utters ‘I am making a mess’, then he self-ascribes the property of making a mess, and therefore he believes that property. An agent who seemingly believes a purely general qualitative proposition \(P\) in fact believes the corresponding property of being such that \(P\). For example, if John sincerely utters ‘Some dogs are brown’, he believes (self-ascribes) the property of being such that some dogs are brown.