History of using "fact" as an interjection

Solution 1:

You asked,

What is the history of this device?

Was there a single speaker who first used and popularized it, or did it develop organically?

Fact may sound like an interjection in spoken English due to the speaker's emphasis, but really, it's connected to what follows. So I disagree that using "fact" as an interjection is a device with a history.

I would say that this is a rhetorical device that is not limited to English. I submit that the rhetorical device here is called the colon, meaning, a rhetorical figure consisting of a clause which is grammatically, but not logically, complete.

The propositions that follow the word fact are grammatically complete, but it is that introducing qualifier, fact that (the speaker supposes) establishes those propositions as fact.

Technically, the colon here is the proposition, or clause, that follows the word fact.

To introduce propositions with the word fact, I recommend inserting a colon after the word, instead of a period (full stop) or exclamation point. The reason is that each proposition is being introduced as a fact, and it is important to connect the introducing word fact to the proposition that follows.

To illustrate, I would change the period (full stop) after "fact"...

Fact. 99% of all Grumbles live in swamps. Fact. If Grumbles don't drastically change their mating rituals by 2017, neighboring Floobies will be sick. Fact. Floobies hate being sick.

...to a colon after "fact:"

Fact: 99% of all Grumbles live in swamps. Fact: If Grumbles don't drastically change their mating rituals by 2017, neighboring Floobies will be sick. Fact: Floobies hate being sick.

Here fact not only introduces the proposition that follows, but connects to, and qualifies that proposition. I submit that fact is not being used as a mere interjection, and not merely as a point of emphasis, but as a qualifier.

Similar examples of this usage might be:

Destination: Mars

Dinner: chips and juice.

Example: The quick brown fox jumps over the lazy dog.

Proposed: That all Grumbles are bloogy.

Thesis: People should stop eating meat.

Antithesis: People should continue eating meat.

Synthesis: People should eat meat if they choose, but it should be a small part of their diet....
(above 3 examples of thesis, antithesis and synthesis from http://research.cs.queensu.ca/home/cisc497/resources/ThesisAntithesisSynthesisFramework.pdf )

PS: I miss you terribly!

Generalization: There are two kinds of person

[Writers] should always use a colon to emphasize a connection between two independent clauses, particularly when the second clause explains or gives more information about the first. This is exhibited in the following example:

Love is blind: sometimes it keeps us from seeing the truth.

Many of the students worked in the evenings: six of them were waitresses.

Sometimes it can be difficult to determine whether the two clauses are merely related, warranting a semicolon, or represent a sequence of thought, warranting a colon. Adding a full stop and separating the clauses into two independent sentences serves as a third option. In these cases, as with many of the gray areas of grammar, there may not be one "right" answer.

From https://www.scribendi.com/advice/semi_colon_and_colon.en.html

Additional examples below:

If the introductory phrase preceding the colon is very brief and the clause following the colon represents the real business of the sentence, begin the clause after the colon with a capital letter:

Remember: Many of the prominent families of this New England state were slaveholders prior to 1850.

If the function of the introductory clause is simply to introduce, and the function of the second clause (following the colon) is to express a rule, begin that second clause with a capital:

Let us not forget this point: Appositive phrases have an entirely different function than participial phrases and must not be regarded as dangling modifiers.

From http://grammar.ccc.commnet.edu/grammar/marks/colon.htm