 This view of the relationship between (L1) and (L2), however, assumes that there is one and only one set of logical constants for each system of representations. A contrary view holds that which expressions are treated as logical constants is a matter of choice, with different choices serving different purposes. If we fix, say, ‘believes’ and ‘knows’ then we can see that ‘\(x\) believes that \(p\)’ is implied by ‘\(x\) knows that \(p\)’ (given widely held views about knowledge and belief). This does not mean that ‘believes’ is a logical constant in an absolute sense. Given other interests, other expressions can be treated as logical. According to this conception, different formal languages will be useful in modeling the inferences that are formally valid given different set of ‘logical constants’ or expressions whose meaning is kept fixed.