得る/得ない — Can/Cannot, Possible/Impossible

Meaning & Usage

The grammar pattern ～得る (～うる／～える) and its negative form ～得ない (～えない) are formal expressions for theoretical possibility and impossibility. They attach to the masu-stem of a verb to make a specific kind of claim: not "I personally can do this," but "this can conceivably happen" — possibility at a universal or abstract level, not individual ability.

The kanji 得う literally means "to obtain" or "to be able to." When appended to a verb stem, it forms a compound that means "it is possible to [verb]" or "one can [verb]." Its negative counterpart, ～得ない, asserts the opposite: "it is impossible to [verb]" or "it is inconceivable that [verb] would happen."

An important detail: 得る has two acceptable readings in this grammatical pattern:

• うる — the classical, literary reading (e.g., あり得うる — formal written style)
• える — the more modern reading (e.g., あり得える — also widely accepted)

However, the negative form 得ない is always read as えない. There is no such form as うない — a common trap for learners. The asymmetry between the positive and negative readings is one of the most important things to memorize for this grammar point.

As a rule, ～得る is a formal, written-language expression. You will encounter it in newspaper editorials, academic research papers, legal documents, formal business reports, and literature. It sounds unnatural in casual everyday speech, with the notable exception of あり得えない (ありえない), which has become so widely used that it appears freely in casual conversation, social media, anime, and manga.

Compared to English, ～得る corresponds to phrases like "can possibly," "it is conceivable that," "it is within the realm of possibility," or simply "can/could" in a formal context. The negative ～得ない maps to "cannot possibly," "it is inconceivable," "it is out of the question," or "there is no way."

What sets ～得る apart from できる comes down to scope. できる expresses personal ability or practical capability ("I can speak Japanese"). ～得る expresses theoretical or logical possibility — whether something can exist or occur in the world, regardless of who you are. Think of ～得る as answering: Is this within the space of things that can conceivably happen? If yes, use ～得る. If no, use ～得ない.

Structure & Formation

The pattern attaches to the 連用形れんようけい (masu-stem) of a verb — the form obtained by removing ます from the polite present form:

Formation summary:

• Positive: Verb masu-stem + 得うる (うる) or 得える (える)
• Negative: Verb masu-stem + 得えない (えない)
• Past positive: Verb masu-stem + 得えた (えた)
• Past negative: Verb masu-stem + 得えなかった (えなかった)

Important note on suru-verbs: Compound verbs ending in する use the stem し before adding 得る or 得ない (e.g., 理解りかいする → 理解りかいし得うる). This is the same masu-stem formation rule applied consistently across all verb types.

Example Sentences

Basic Possibility and Impossibility

Natural Events and Scientific Contexts

Formal Academic and Business Contexts

Human Behavior and Emotions

Expressing Scope and Limits

Common Mistakes

Mistake 1: Using うない as the negative form

❌ そんなことはありうない。

✅ そんなことはあり得えない。

The negative form is always 得えない (えない), never うない. While the positive form 得る can be read as either うる or える, the negative has only one reading: えない. This asymmetry often surprises learners who try to negate the うる form directly. Remember: positive = うる or える; negative = えない, every time.

Mistake 2: Confusing ～得る with できる for personal ability

❌ 私わたしは日本語にほんごを話はなし得うる。(meaning: I can speak Japanese)

✅ 私わたしは日本語にほんごを話はなすことができる。

While ～得る is not grammatically wrong in the first sentence, it sounds highly unnatural when expressing personal ability. できる and the verb potential form (話せる) are the correct tools for personal skill or capability. Reserve ～得る for theoretical, abstract, or impersonal possibility — statements about what is logically possible in the world, not what you personally can do.

Mistake 3: Attaching 得る to the dictionary form instead of the masu-stem

❌ 起おこる得うる ✅ 起おこり得うる

得る must always attach to the masu-stem (連用形れんようけい) of the verb. For the godan verb 起おこる, the masu-stem is 起おこり (from 起おこります). For ichidan verbs like 考かんがえる, the masu-stem is 考かんがえ. For suru-compound verbs, always use し. Never attach 得る directly to the plain dictionary form of the verb.

Mistake 4: Using ～得ない for practical inability instead of logical impossibility

❌ 今日きょうは仕事しごとが忙いそがしくて行いき得えない。

✅ 今日きょうは仕事しごとが忙いそがしくて行いけない。

得ない expresses logical or theoretical impossibility, not practical inability due to circumstances. When explaining that you personally cannot do something because you are busy, tired, or lack time, use the verb's potential negative form (行けない, 来られない, できない). Using 得ない here implies that going somewhere is a logical impossibility — as if the laws of physics forbid it, rather than your schedule.

Mistake 5: Overusing ～得る in casual conversation

❌ ねえ、それってまた起おこり得うるよね？ (too stiff for casual conversation)

✅ ねえ、それってまたあり得えるよね？ or ～かもしれないよね？

The pattern ～得る with verbs other than ある is primarily a formal written register. In casual speech, using 起おこり得うる or 考かんがえ得うる can sound overly stiff and unnatural. In everyday conversation, reach for ～かもしれない (might), ～可能性かのうせいがある (there is a possibility), or simply rephrase. The one exception is あり得る / あり得ない, which has fully entered colloquial speech and is perfectly natural in casual contexts.

Cultural Notes

The expression あり得えない (ありえない) has evolved dramatically from its formal written origins. Once confined to documents and formal speech, it is now one of the most common exclamations in modern Japanese. Young speakers use it to express shock, disbelief, or strong disapproval: 「それ、ありえない！」 ("That's impossible!" / "No way!"). On social media, in anime dialogue, and in everyday conversation, あり得ない functions almost like an adjective, with forms such as 「ありえなくない？」 ("Isn't that totally unacceptable?") appearing regularly in informal writing.

Other forms of ～得る remain firmly in the formal register. Government white papers, newspaper 社説しゃせつ (editorials), academic journals, and legal documents regularly employ forms like 起おこり得うる or 考かんがえ得うる. Fluent recognition of these forms is a practical must for anyone reading professional Japanese — and a clear signal of N2-level reading ability.

The classical reading うる for the positive form carries a distinct literary gravitas. Authors, essayists, and opinion writers sometimes deliberately prefer the うる reading over the more modern える to lend their writing an authoritative, scholarly tone. This distinction is invisible in spoken language but carries subtle stylistic weight in print. Few grammatical forms in modern Japanese manage this — staying classical without sounding archaic.

JLPT Tips

On the JLPT N2 exam, ～得る／得ない appears most frequently in 読解どっかい (reading comprehension) sections rather than in grammar selection questions. Formal essay passages, news-style articles, and academic excerpts regularly use this pattern, so being able to recognize it at a glance — without pausing to decode it — will save you real time on the reading sections.

In grammar selection questions, the most common trap is distinguishing between ～得ない and ～かねない. Remember the key contrast: ～得ない = it is logically or theoretically impossible; ～かねない = there is an undesirable risk that something might happen. For example, 「事故じこになり得えない」 would mean "an accident is impossible" (a reassuring statement), while 「事故じこになりかねない」 means "this could lead to an accident" (a warning). Mix them up and you will likely flip the meaning of the sentence entirely.

Pay special attention to the reading of 得 in multiple-choice questions. The positive form 得る can be either うる or える — both are correct. The negative form 得ない, however, is always read えない. If a question asks about the reading of 得ない, the answer is always えない.

Watch for vocabulary that signals ～得る is nearby: 可能性かのうせい (possibility), 理論的りろんてきに (theoretically), 想定そうてい (assumption), 仮説かせつ (hypothesis). Passages on risk, scientific research, or social policy are prime territory for this pattern. Recognizing that context helps you confirm the polarity quickly and read the author's intent correctly.

Finally, あり得える / あり得えない is by far the most frequently tested form. Make sure you can parse it instantly and distinguish it from similar-looking expressions. In particular, あり得ない appears in reading passages both as a formal assertion ("X is impossible") and as a character's exclamation expressing shock or disbelief. Knowing both uses sharpens your answers on intent and tone questions.