text: **Internal structure**
  
  Premises and conclusions have an internal structure. As propositions or sentences, they can be either 
  simple or complex.[48] A complex proposition has other propositions as its constituents, which are linked 
  to each other through propositional connectives like "and" or "if...then". Simple propositions, on the other 
  hand, do not have propositional parts. But they can also be conceived as having an internal structure: they 
  are made up of subpropositional parts, like singular terms and predicates.[49][48] For example, the simple 
  proposition "Mars is red" can be formed by applying the predicate "red" to the singular term "Mars". In 
  contrast, the complex proposition "Mars is red and Venus is white" is made up of two simple propositions 
  connected by the propositional connective "and".[49] 
  
  Whether a proposition is true depends, at least in part, on its constituents. For complex propositions 
  formed using truth-functional propositional connectives, their truth only depends on the truth values of 
  their parts.[49][50] But this relation is more complicated in the case of simple propositions and their 