Have you ever wondered why Japanese sometimes requires 多くの instead of just 多い when describing quantities? I certainly did, so I went and took a look at some linguistic research discussing this fascinating quirk of Japanese grammar.

I tried my best to understand the research and provide a reasonable explanation build on it. The paper, as always, is linked at the end of the post.

I will mark words with an asterisk (*) to show that the Japanese grammar will allow for this, but that has nothing to do with its acceptability in day-to-day use.

The Problem

In Japanese, we have two ways to express “many”:

• 多くの and ◯◯が多い

But interestingly, you can’t just use 多い directly before a noun:

As noted in academic research from Nagoya Gakuin University (2008), this pattern isn’t random. The paper points out that while 多い works perfectly fine in predicative positions (like saying “X is many”), it requires transformation into 多くの when directly modifying nouns.

Let’s get into it!

Understanding Predicates and Quantity Adjectives in Japanese

A predicate is the part of a sentence that tells us something about the subject. In Japanese, this typically appears at the end of the sentence. For quantity expressions like 多い, predicative use means it comes after the thing being quantified.

The thing being quantified is marked by が.

The Quirk of Quantity Adjectives

Interestingly, both 多い and 少ない share a similar restriction. As the paper points out right away, Sugimoto (1982) noted in his study that sentences like:

are unacceptable, even though 少ない works perfectly fine in predicate positions:

Pattern Recognition

This pattern isn’t unique to just these two adjectives. Looking at other quantity-related adjectives in Japanese, we can see similar behaviors. For example, when expressing spatial quantities:

But not:

However, as the paper notes, these spatial modifiers function differently from pure quantity expressions. With 近く and 遠く, we’re actually using them as nouns meaning “vicinity” rather than as adverbial forms of the adjectives.

The research emphasizes that 多い and 少ない are unique in this restriction – other measure-related i-adjectives like 大きい (big) and 小さい (small) don’t show this pattern. This suggests there’s something special about adjectives that directly express quantity rather than size or other measurable qualities.

Why This Is

The paper introduces an important categorization, dividing quantity expressions into two types:

C-対表現 (Comparative Expressions)

1. 多い (many, implies comparison to expected amount)
2. 少ない (few, implies comparison to expected amount)
3. 高い (high/expensive, compared to standard)
4. 低い (low, compared to standard)
5. 深い (deep, compared to standard)
6. 浅い (shallow, compared to standard)
7. 長い (long, compared to standard)
8. 短い (short, compared to standard)
9. 広い (wide, compared to standard)
10. 狭い (narrow, compared to standard)

N-対表現 (Numeral Expressions)

1. たくさん (many/much)
2. 少し (a little)
3. 大勢 (many people)
4. いっぱい (lots)
5. かなり (quite a few)
6. わずか (a few)
7. いくらか (some amount)
8. 相当 (considerable amount)
9. 若干 (slight amount)
10. たっぷり (plenty)

Key Differences

The paper demonstrates these differences through examples:

But you can’t use N-対表現 this way:

The Comparative Nature

The C-対表現 always involve an implicit or explicit comparison, even when not in a comparative sentence. For example:

This differs from N-対表現:

The key distinction is that C-対表現 always involve some form of comparison against a standard or expectation, while N-対表現 simply state quantities without this comparative element.

The Case Of 多い and 少ない

Now, why can’t we use 少なくの?

We now know there are numeral and comparative adjectives. The numeral ones we use when we count to represent the value, the comparative ones we use when we want to compare values:

1. When we COMPARE to a standard or expectation:
   “There are fewer students than last year” (去年より50名少ない)
   “There are more students than last year” (去年より50名多い)
2. When we just COUNT from zero:
   “There are 50 students” (50名の学生がいる)
   “There are 200 students” (200名の学生がいる)

多い is simple because these always match:

• If comparing: More than expected = 多い
• If counting: Counting is upwards (we start from zero -> 1,2,3,4 … -> getting more) = 多い
  Both ways think about “more” the same way

But 少ない creates a conflict:

• If comparing: Less than expected = 少ない (thinking downward)
• If counting: We still have to count up from zero to whatever number (the number gets more)

This is why we can’t say “*少なくの学生”. It’s trying to say both “count up to this number” and “think about having less than expected” at the same time. The grammar doesn’t allow this contradiction.

Part of its DNA is saying “going down toward zero”. But another part is saying “counting up from zero”.

Why It Works As A Predicate

Now, why can we use these expressions as predicates? Why can we say somethingが多い or somethingが少ない? As we established just now, both adjectives are used comparatively, showing either a larger or lesser amount. The が marked subject is always telling us a clear standard of comparison. Let me show you some examples from the paper:

• Explicitly stated: 去年より学生が多い/少ない (more/fewer than last year)
• Implicitly understood: 学生が多い/少ない (more/fewer than expected/normal)

The key difference between predicate use (〜が多い/少ない) and attributive use (*多い/少ない学生) is that with predicates:

• The comparison standard is either clearly stated or understood from context
• The subject (what’s being compared) is already established by が
• The comparative meaning has a clear target

But when trying to modify a noun directly, there’s no clear:

• Standard for comparison (compared to what?)
• Subject-standard relationship structure

That’s why we need special forms like 多くの or constructions like たくさんの for attribution, but can use the basic forms 多い/少ない freely as predicates where the comparative relationship is structurally clear.

I have talked about の’s categorization function in this post. We use the infinitive く to make the adjective nominal (the infinitive is always nominal in Japanese) and add the noun to the that category using の. If this sounds confusing, I suggest reading said post about の.

• 多く -> Existing plentifully, manifold

Examples

The paper shows this contrast through several examples:

This works because それでなくても (already/even without that) establishes the hair first (it contradicts it), before the quantity judgment.

Compare with the unacceptable:

or these examples showing the same situation:

Why We Can Use 多い

Now, this is where 多くの comes in:

The の particle is doing crucial work here – it creates a grammatical bridge that allows us to:

1. Establish the quantity concept as a nominal element (多く)
2. Adding the element (学生) to the group of manifold things through の

Now What is 多くの Really?

Based on the paper’s analysis, 多くの isn’t just a grammatical workaround – it’s a sophisticated solution that allows Japanese to express quantity modification while maintaining logical order. It transforms the problematic direct attribution of 多い into a grammatically and logically sound structure where:

• The quantity concept is established (多く) as a nominal element
• The connective の allows proper modification
• The target noun (学生 etc.) can thus be properly identified and quantified

Source

https://www2.ngu.ac.jp/uri/gengo/pdf/genbun_vol1902_02.pdf