Pronouns

An antecedent logically shows up at the correct time in an ordered series. It can also give specific meaning to a pro-adverb, pro-verb or pro-noun.

The forms of the demonstrative pronoun in English are this, that, these, and those. You use these words to point at objects in the world, depending on whether they are near or far from your body, and also depending on whether there is one object or more than one object.

The demonstrative pronoun is different from the demonstrative adjective because whereas the latter qualifies a noun, the former just replaces the relevant noun altogether.  

The main role fulfilled by the indefinite pronoun is to allow the speaker to make a statement in generic terms, without necessarily defining the specific persons of whom the sentence is speaking.

The phrase, "One could say," is a good example of this: the pronoun doesn't specify who can say something; it merely indicates that some human being, somewhere, could say. It is important, though, to use the indefinite pronoun for a real purpose and not just degenerate into vagueness.