Want & Can: ~고 싶다, ~(으)ㄹ 수 있다
Express what you want to do and what you are able to do.
Expressing desire and ability in Korean unlocks a huge range of natural conversation. -고 싶다 attaches to a verb stem to mean 'want to': 가다 (go) → 가고 싶다 (want to go) → 가고 싶어요 (polite: I want to go). The pattern is identical for any verb.
-(으)ㄹ 수 있다 / 없다 expresses ability: 하다 → 할 수 있어요 (I can do it) / 할 수 없어요 (I cannot do it). The (으) appears after consonant-ending stems for euphony. The phrase 수 있다 literally means 'there is a way', which is a natural way to express possibility in Korean. Note the contrast with 못 from Lesson 3-4: -(으)ㄹ 수 없다 is a softer way of saying 'cannot', while 못 is more direct. In conversation, Koreans often soften refusals using 못 하겠어요 or 못 할 것 같아요 instead of a flat 안 해요, which can sound rude.
~고 싶다 — Want to do
Attach 고 싶다 to the verb stem (remove 다). 가다 → 가고 싶어요 (I want to go). For past: 고 싶었어요 (I wanted to).
~(으)ㄹ 수 있다/없다 — Can / Cannot
Verb stem + (으)ㄹ 수 있다 = can do. If stem ends in consonant → 을 수 있다, vowel → ㄹ 수 있다. Replace 있다 with 없다 for 'cannot'.
How It Works
-고 싶다 attaches to a verb stem and expresses desire. The construction is clean: drop 다, add 고 싶다, then conjugate 싶다 normally. 가다 becomes 가고 싶어요, and the past is 가고 싶었어요. Since 싶다 carries the conjugation, the main verb never changes form — a convenience that makes this one of the easier patterns at this level.
-(으)ㄹ 수 있다 expresses ability, and the shape depends on the stem ending. After a consonant you get -을 수 있다; after a vowel or ㄹ you get -ㄹ 수 있다. 먹다 gives 먹을 수 있어요; 가다 gives 갈 수 있어요. Replacing 있다 with 없다 gives the negative: 갈 수 없어요.
The literal structure is worth seeing because it explains the meaning. 수 is a noun meaning roughly 'way' or 'means', so 갈 수 있어요 says 'there exists a way to go'. Korean expresses possibility as the existence of a method rather than as an internal capacity, which is why it feels softer than a flat 'I can'.
That softness is the key contrast with 못 from the previous lesson. -(으)ㄹ 수 없다 says no way exists; 못 says an attempt is blocked. They overlap but are not identical, and 못 is the more direct of the two.
Where You'll Hear It
-고 싶다 is how travel and food conversations begin. 한국에 가고 싶어요, 떡볶이를 먹고 싶어요, 한국어를 배우고 싶어요 — these are the sentences that let you talk about your own motivations, which is usually what people ask a language learner about first.
-(으)ㄹ 수 있다 handles both skills and permission. 한국어로 말할 수 있어요 describes an ability; 여기에서 사진을 찍을 수 있어요? asks whether photography is allowed. The same construction covers both, so it does a great deal of practical work in travel situations.
The softening effect matters socially. Koreans frequently decline using 못 하겠어요 or 못 할 것 같아요 rather than a flat 안 해요, because a bare refusal can read as abrupt. Understanding that -(으)ㄹ 수 없다 and these hedged forms are politeness strategies, not just grammar, helps you decline invitations without sounding cold.
One restriction to remember: -고 싶다 in a plain statement describes only your own desire. Talking about what someone else wants requires 고 싶어하다.
Cultural & Language Note
고 싶다 can only describe your own desire in a plain statement. To talk about what someone else wants, Korean switches to 고 싶어하다 — a grammatical acknowledgement that you cannot directly know another person's inner state. Japanese does exactly the same thing with たい versus たがる, so this rule needs no explanation for Japanese speakers.
Common Mistakes to Avoid
Saying 친구가 가고 싶어요 to mean 'my friend wants to go' is the standard error; it needs 가고 싶어해요. For 을 수 있다, remember it expresses ability or possibility, while 못 expresses a blocked attempt — 갈 수 없어요 and 못 가요 overlap but are not identical in nuance.
How to Practice This Lesson
Start with -고 싶다 because it is mechanically simple and immediately useful. Write ten things you actually want to do and say each one. Personal content means you will remember the sentences and reuse them, which is not true of textbook examples.
For -(으)ㄹ 수 있다, drill the consonant/vowel split separately from the meaning. Take five consonant-final stems and five vowel-final stems, and produce the correct form for each without thinking about what they mean. Once the shape is automatic, attach it to real content.
Then practise declining politely, because this is a genuinely useful social skill and it uses both patterns. Take three invitations you might want to refuse and construct soft refusals: 오늘은 좀 못 갈 것 같아요. Being able to say no gracefully is worth more early on than being able to say yes.