Most Americans have heard people say both, “It’s not that big a deal,” and “It’s not that big of a deal,” and many are not certain which of the two constructions is considered correct. The former phrase is correct, meaning that it is acceptable in all registers of English; the latter is a false partitive. It’s a dialectical construction that is not considered grammatical in the most formal registers of standard English, although it is becoming more common in casual speech.

The word “big” is an adjective; as such it is not entitled to govern a prepositional phrase. In the sentence, “It’s not that big a deal,” “big” modifies, or describes, “deal.” The sentence could be rewritten as “It’s not a deal that big,” or “The deal is not that big.” It is neither necessary nor permissible to insert “of” into the sentence.

“So great a thinker as Socrates” follows the same construction as “that big a deal.” “So” is an adverb modifying “great,” and “great” is an adjective modifying the noun “thinker.” No preposition may divide the adjective from the noun that it modifies. Just as “It’s not that big a deal” is an inversion of “it’s not a deal that big,” “so great a thinker as Socrates” is an inversion of “a thinker so great as Socrates.”

Where did the dialectical “of” come from?

In English, a partitive is a construction consisting of a quantitative noun followed by a prepositional phrase introduced by “of.” “Two of them,” “a lot of books,” “a couple of geese,” and “a few of those flowers” are all partitive phrases. “A whale of a time” is also a partitive; “whale,” in this context, denotes fun on an enormous, whale-sized, scale. Some quantitative nouns can also serve as adjectives. “Two” in “two of the books” is a noun, but in the phrase “two books,” “two” is an adjective; “few” is a noun in the partitive phrase “a few of those flowers” but an adjective in the phrase “few flowers.”

The grammar of this construction may seem confusing, because many nouns that indicate quantity are also adjectives. “Much,” “more,” “less,” and “enough” can all be adjectives, adverbs, or nouns. In the phrase “much of this,” much is a noun. Similarly, in the sentence, “We have enough of these,” “enough” is a noun. But because these words are also adjectives, these phrases sound like an adjectival grammatical pattern, which they are not.

The false partitive arose by analogy with this pattern. Adjectives, however, cannot enter into the partitive as quantitative nouns, or as nouns at all. That is why “so big of a deal” is a false partitive, not a true one.

When I published this article in the Examiner.com a few years ago, I concluded by saying that the false partitive may truly be a big deal, because it creates the impression that the speaker is not well educated. Meanwhile, the false partitive continues to gain ground. Languages change over time, but the more formal registers of language remain more conservative. (The more formal the register, the more conservative the grammar. No, one absolutely cannot say, “The more formal *of the register, the more conservative *of the grammar.”)

The false partitive began as dialectical, meaning that it was used in certain dialects but not in others, and not in standard English. Speakers of standard English are using it more and more; is it still considered substandard or problematic? It would certainly still be out of place in a formal essay or book, except in dialogue. I would advise against using it during a job interview for a position requiring knowledge of the more formal registers of English. It would not be out of place in casual conversation, however, but many a curmudgeon may respond with so evident a shudder as to remind you how big a deal so dialectical a phrase remains.

A slightly different version of this article was published on October 11, 2012 on the Examiner.com, a site that is now defunct.