 The machinery that formally describes the internal structure of propositions is referred to as predicate logic. And an essential idea in predicate logic is that each proposition can be defined as a predication. Predications in turn consist of a predicate, which is always capitalized, and a set of arguments that are presented in small letters. Let's illustrate that. The proposition P, John, loves Mary, can be broken apart into a predicate, love, and two arguments, John and Mary. This can be presented as a predication where the arguments are constants. Since propositions are generally taken to be tenseless, predicate labels do not indicate tense either. So, love is a predicate with two arguments, a so-called two-place predicate, where the arguments are variables that are filled, in this case with John and Mary. So predications consist of two basic elements, predicates and their arguments. Each predication may have only one predicate, but may have one or more arguments. Let's look at further examples. The first is a simple predication where the one-place predicate country assigns some property to its argument. Great Britain is a country. The second predication is complex. It has a three-place predicate where some relationships between the entities denoted by the arguments are represented, as in Jane sends Paul a letter. And the last predication involves the two-place predicate with a predication as its second argument. The teachers saw that the children were reading some books. So predications can be arguments of predicates too.