The demonstrative pronouns this and that and their plural forms these and those
are important but often-misused pronouns. Consider the following examples:
An author might list several items in a paragraph and then end the paragraph with "This is a very important thing to remember." Which thing? It's not clear which item this specifically refers to.
An author might begin a paragraph with this but fail to mention what this refers to (the referent).
Here's a talking point: Person 1 might make a statement and person 2 might reply, "This is true." No, actually, that is true. Person 2, when referring to person 1's statement, is not correct in using this because person 2 doesn't own the original statement.
Fortunately, these errors are easily corrected:
1. When using this (or the plural form these), make sure the thing you're referring to is close by (as in the same sentence or in the previous sentence). If your this statement and the thing you're referring to is separated by a sentence, then you need to revise it and state the actual words you're referring to.
2. Don't start a paragraph with This. State the actual thing you're talking about. Or else combine paragraphs to avoid restating.
3. Don't be afraid of using the words that and those. In a conversation, when referring to someone else's statement, use that or those. In text, when referring to something not close by in text, use that or those along with the actual noun you're referring to.