  One philosophical objection to \(\mathbf{FL}\) is that \(E\) appears to be an existence predicate, and many would argue that existence is not a legitimate property like being green or weighing more than four pounds. So philosophers who reject the idea that existence is a predicate may object to \(\mathbf{FL}\). However in most (but not all) quantified modal logics that include identity \((=)\) these worries may be skirted by defining \(E\) as follows.