What is the proper term for this part of a statement?

Question

In a statement such as the one in the example below, what is the term (is there a term?) used to refer to the this and/or that?

I like this more than that.

In the above example, the this/that could easily be replaced with a noun. However, the idea could also be expanded to something like this:

I thought that I would be more tired than I actually ended up being.

If I am to parse this out and categorize the statements in the same way, this would equate to I would be more tired and that to I actually ended up being, despite the internal structures of the two examples being very different.

Answer 1

What is being done there is a pro-form substitution (replacement); "this/that" are called pro-forms.

I think that in this case "a pronoun substitutes a noun or a noun phrase, with or without a determiner" such as it or this.

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Add-on: By the way, seeing that others include the explanation of deictics, I thought I'd include it too.

I didn't mention it because it didn't seem fundamental to answer your question, but it can add value to the discussion. Like others said, we have deictics in languages. They are highly dependent to the context, and if you listen to an audio conversation, they might represent a problem if you want to fully understand that dialogue. I had some notes about this matter: "Deictic" comes from the Greek word for "pointing" or "indicating". It is reference by means of an expression whose interpretation is relative to the context of the utterance, such as:

a) who is speaking
b) the time or place of speaking
c) the gestures of the speaker
d) the current location in the discourse
e) the topic of the discourse

If near speaker, proximal terms are used (this, here, now); if away from speaker, distal terms are adopted (that, there, then). Speakers and hearers constantly adjust their internal registry of deictics to keep up with the conversation.

Traditionally, by deixis is meant the location and identification of person, objects, events, processes and activities being talked about, or referred to, in relation to the spatiotemporal context created and sustained by the act of utterance and the participation in it, typically, of a single speaker and at least one addressee; we can analyze them this way:

1. Person deixis: those that are used to refer to speaker and addressee (I, you, we)
2. Place deixis: those that refer to spatial context (here, there)
3. Time deixis: these that refer to temporal context (now, then, verb tense markers)
4. Discourse deixis: those that refer to parts of unfolding discourse (next, below, furthermore)
5. Social deixis: those that encode aspects of the social relationship between speaker and addressee (Her Majesty)
6. Perceptual deixis: There's Harry

Answer 2

The words this and that are demonstrative pronouns. The sentences "I would be more tired" and "I actually ended up being" have the same syntactic function as "this" and "that" would have. But, being full clauses (instead of simple pronouns), they are classified as subordinate or dependent clauses. In your examples, they function as direct objects of the verb "think".

Note that in your second example, the word "that" is also being used to introduce one of the subordinate clauses. But, in that case, it is a subordinating conjunction.

Answer 3

Otavio is right. These are demonstrative pronouns.

More importantly, this and that are Deictic Expressions, having meaning only in the contexts of the actual speech act. They're only a small fraction of the deictic paradigms that English used to have.

For details on deictic expressions, see Fillmore's classic "May We Come In?" and his description of deixis in the Deixis Lectures.