A compound statement in grammatical sense is independent of its components as far as its truth-value is concerned. However, in logical sense the truth or falsity of compound proposition depends upon the truth or falsity of its components. Simple proposition does not need any definition. It consists of only one sentence in grammatical sense. Compound statement, on the other hand, consists of two or more than two ‘statements’. In other words, the components of a compound statement may be simple or themselves compound. Consider the following examples:
1) Grass is green.
2) Einstein is a physicist and Lorenz was his professor.
3) Descartes is a philosopher and mathematician.
The first statement is simple and the second statement is compound. Third statement seems to be a simple proposition. In reality, it is a compound statement. It can be analysed as follows: Descartes is a philosopher and Descartes is a mathematician. In the language of predicate logic compound proposition can be understood as follows; if there are two predicates then there are two propositions. And if there are three predicates, then there are three propositions and so on.