When Passive and Causative Look Identical (보이다, 업히다, 읽히다)

Korean has a genuinely awkward piece of design at its core: the same four suffixes — 이, 히, 리, 기 — build both the morphological passive and the morphological causative. Because a verb usually draws its passive and its causative from the same suffix, a large family of derived verbs ends up spelled and pronounced identically in the two voices. 보이다 is "be seen" and "show"; 업히다 is "be carried on the back" and "make (someone) carry"; 읽히다 is "be read" and "make read." The verb form gives you no clue which one is meant. This page shows you the systematic overlap and, more importantly, the reading procedure that resolves it every time.

The overlap is systematic, not accidental

For most suffix verbs, the passive and the causative are the same word. The reason is historical — one Old Korean suffix split into two functions — but the practical upshot is a permanent ambiguity you have to parse your way out of.

The disambiguation lives in the particles, never the verb

Here is the single most important fact: the two readings differ in argument structure, not in form. A passive and its causative twin take completely different frames of particles, and that is what tells them apart.

• The passive has a patient-subject (the thing the action happens to) and, optionally, an agent in 에게/한테. That's it — two participants at most.
• The causative has a causer-subject (who makes it happen), a causee in 에게/한테 (who is made to act), and usually an affected object in 을/를. Three participants.

Watch the same verb, 업히다, in both frames:

In the first, 아기가 is the subject and the only real participant besides a location — the baby simply is carried. In the second, there are three: 엄마가 (causer), 아기를 (the affected object), 할머니에게 (the causee). Nothing about the word 업혔어요 changed; the cast of particles changed, and that is what flips passive into causative.

A step-by-step reading procedure

When you meet a suffix verb and aren't sure of its voice, run these three checks in order:

1. Is there a 를/을 object and a separate 에게/한테 participant? If yes, it's a causative — the 를-thing is what gets affected and the 에게-person is who's made to act.
2. Is the subject the thing being acted upon, with at most one 에게/한테 agent behind it? Then it's a passive.
3. Still tied? Fall back on plausibility and context. Babies get held (passive) far more often than handed-over-to-be-held (causative), so the bare 아기가 안겼어요 defaults to passive; add a causer and an object and it becomes causative.

Apply it to 읽히다:

Both contain 학생들에게 and the same verb, but the first has the poem as subject (이 시는) and no object — patient-subject → passive. The second has the teacher as subject (선생님이) and 시를 as an object — causer + object + causee → causative. The procedure sorts them instantly.

보이다: the cleanest minimal pair

보이다 makes the ambiguity especially vivid because both readings are everyday. As a passive it means "be visible"; as a causative, "show" (make someone see). The present-tense form 보여요 is identical for both.

The passive 보여요 has a patient-subject (남산타워가) and no object; the causative 보여요 has an object (표를) and a person to show it to (직원에게). In practice, the causative "show" is very often reinforced with 주다 — 표를 보여 줬어요 "I showed the ticket" — which removes all doubt. That is not a rule, but a strong habit worth copying.

안기다 and 물리다 round out the pattern

Each pair is the same verb in the same past tense. The passive has the sufferer as subject and an agent in 한테; the causative adds a causer-subject and a 를-object. The verb is a spectator; the particles do all the work. For the causative side of these particles in depth, see case marking in causatives and the causative suffix -이-.

Common Mistakes

1. Reading a causative as a passive. In a three-participant frame, 업혔어요 / 안겼어요 / 읽혔어요 are causatives — don't translate them as "was carried / was held / was read."

2. The double-passive ×보여지다. Because 보이다 already is the passive of 보다, adding -어지다 (보여지다) stacks two passives. It's rampant in real writing, but prescriptively wrong.

3. Trusting the verb form to signal voice. There is no morphological tell. 읽혀요 out of context is genuinely ambiguous; you must read the particle frame.

4. Dropping the object that marks a causative. Without the 을/를 object, a would-be causative collapses into a passive reading.

Key Takeaways

• The same 이/히/리/기 suffix builds both passives and causatives, so verbs like 보이다, 업히다, 읽히다, 안기다, 물리다 are homophonous across the two voices.
• The voice is decided by argument structure, not verb form: patient-subject (+ optional 에게-agent) = passive; causer-subject + 에게-causee + 을/를-object = causative.
• Run the check: a 를-object plus a separate 에게-participant means causative; a patient-subject alone means passive.
• Watch the double-passive ×보여지다 — 보이다 is already passive, so 보여요 is enough.