 Popper offers two accounts of how rival theories can be compared in terms of their levels of verisimilitude; these are the qualitative and quantitative definitions. On the qualitative account, verisimilitude is defined in terms of subclass relationships: a theory \(t_2\) has a higher level of verisimilitude than \(t_1\) if and only if their truth- and falsity-contents are comparable through subclass relationships, and either