Scii or Koni? | Esperanto Grammar

English know covers two central meanings that Esperanto normally separates. Use scii when the knowledge can be expressed as information, an answer, or know-how. Use koni when someone is acquainted with or familiar with a person, place, work, object, or field.

The fastest test is: can you naturally continue with “that…,” “whether…,” “who/where/why…,” or “how to…”? Choose scii. Can you replace know with “be familiar/acquainted with”? Choose koni.

The quick decision

Intended knowledge	Choose	Typical frame
a fact or proposition	scii	scii, ke...
an answer to a question	scii	scii kiu/kie/kial/ĉu...
learned know-how	scii	scii + infinitive
a known datum	scii	scii la adreson/respondon
personal acquaintance	koni	koni iun
familiarity through experience	koni	koni urbon/libron/temon

The dedicated references for scii and koni give their wider word families.

Use scii for facts and answers

Mi scias, ke la biblioteko fermiĝas je la sesa.

I know that the library closes at six.

The object of knowledge is a proposition: ke la biblioteko fermiĝas...

Ĉu vi scias, kie ni povas aĉeti biletojn?

Do you know where we can buy tickets?

Neniu sciis, ĉu la trajno ankoraŭ veturos pro la ŝtormo.

Nobody knew whether the train would still run because of the storm.

Indirect questions naturally select scii because the unknown or known content is an answer.

Scii can also take a noun that packages information:

Mi ne scias ŝian novan adreson, sed Leo certe scias ĝin.

I do not know her new address, but Leo certainly knows it.

An address here is a datum that one can state. Similarly, one can scii la respondon, la veron, la daton, la prezon.

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If the noun names information that could fill a blank on a form or answer a question, scii is usually the right verb.

Use scii + infinitive for know-how

Ŝi scias ripari biciklojn, sed ŝi ne havas la ĝustajn ilojn hodiaŭ.

She knows how to repair bicycles, but she does not have the right tools today.

Ĉu viaj infanoj jam scias naĝi?

Do your children already know how to swim?

The infinitive names an ability whose procedure has been learned. Scipovi can emphasize practical competence—literally “know-be-able”—but plain scii + infinitive is established and neutral.

Ability and opportunity are different. Ŝi scias stiri says she knows how; ŝi povas stiri hodiaŭ says circumstances or permission allow it today.

Mi scias uzi la programon, sed mi ne povas ensaluti sen la pasvorto.

I know how to use the program, but I cannot log in without the password.

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Separate three English meanings: scii fari is learned know-how, povi fari is ability or permission in the circumstances, and koni ion is familiarity with the thing. “I know this software” may therefore need a different Esperanto verb from “I know how to use it.”

Use koni for acquaintance and familiarity

Mi konas Rubenon de la loka lingvoklubo.

I know Ruben from the local language club.

This is social acquaintance, not knowledge of a fact about Ruben.

Ĉu vi bone konas ĉi tiun kvartalon?

Do you know this neighborhood well?

The question asks about familiarity gained through experience: streets, atmosphere, and practical orientation.

Ŝi konas la romanon tiel bone, ke ŝi povas citi tutajn alineojn.

She knows the novel so well that she can quote whole paragraphs.

A work, song, problem, method, or subject can be familiar as a whole. The adverb bone often reinforces this experiential depth.

La kuracisto bone konas tiun maloftan malsanon.

The doctor is thoroughly familiar with that rare disease.

This does not mean the doctor merely knows that the disease exists; it presents established familiarity with its behavior and treatment.

The central minimal contrast

Mi scias, kie ŝi laboras, sed mi ne konas ŝin persone.

I know where she works, but I do not know her personally.

Scias, kiu ŝi estas gives identifying information. Ne konas ŝin persone denies acquaintance. English uses know twice and hides the distinction.

Mi konas la posedanton de la restoracio, sed mi ne scias lian nomon.

I know the owner of the restaurant, but I do not know his name.

Personal familiarity does not guarantee possession of a particular datum. The reverse is also possible: you can know someone's name without knowing the person.

— Ĉu vi konas la novan instruiston? — Ne, sed mi scias, ke li venis el Kanado.

— Do you know the new teacher? — No, but I know that he came from Canada.

This short exchange is an excellent self-test: koni asks about a relationship; scii introduces a fact.

Scii pri versus koni

Scii pri io often means being aware of something or possessing information about its existence. Koni ion normally suggests more direct or substantial familiarity.

Mi scias pri la problemo, sed mi ankoraŭ ne konas ĉiujn detalojn.

I know about the problem, but I am not yet familiar with all the details.

Ŝi sciis pri la nova programo antaŭ la anonco, sed ŝi ne konis ĝian interfacon.

She knew about the new program before the announcement, but she was not familiar with its interface.

This is not an absolute scale: context can make scii pri include much information. The productive contrast is awareness/information versus familiarity with the thing itself.

Names, places, and languages: inspect the intended meaning

With a city, koni Parizon normally means being familiar with Paris. Scii, kie estas Parizo means knowing its location. With a person, scii pri Marta means having information about Marta, while koni Martan means being acquainted with her.

Languages combine factual knowledge, practical ability, and familiarity, so established usage contains several constructions. Traditional scii lingvon can mean know the language; koni lingvon can emphasize familiarity with it. For active communicative ability, paroli Esperanton, kompreni la japanan, or scipovi la lingvon often states the intended skill more precisely.

Mi iom konas la italan, sed ankoraŭ ne scias paroli ĝin flue.

I am somewhat familiar with Italian, but I still do not know how to speak it fluently.

This is genuine semantic overlap, not free synonymy. Foundational and long-established texts attest noun objects with both verbs in suitable meanings. Pedagogically, the clause/answer/acquaintance test remains the clearest default; corpus evidence helps document preferences in special domains.

Learning changes the type of knowledge

The verbs also pair naturally with different verbs of acquisition. Ekscii means come to know a fact, find out, or learn information. Ekkoni means become acquainted with or begin to know something through contact. Lerni covers learning a skill or body of material and often leads to scii or koni in the resulting state.

Mi eksciis hieraŭ, ke la kandidatiĝo jam finiĝis.

I found out yesterday that the application period had already ended.

What changed was possession of a fact, so eksciis, ke... is exact.

Dum la vojaĝo ni ekkonis multajn lokajn muzikistojn.

During the trip we got to know many local musicians.

Here contact created new acquaintance. Saying eksciis multajn muzikistojn would confuse learning information with meeting people.

Post kelkaj monatoj ŝi jam bone konis la sistemon kaj sciis solvi la plej oftajn problemojn.

After a few months she was already familiar with the system and knew how to solve the most common problems.

The sentence deliberately combines both results: broad familiarity with the system and procedural knowledge for particular tasks.

Negation does not erase the distinction

English I don't know can be a complete conversational reply, but Esperanto still chooses according to what is missing. Mi ne scias answers a factual question. Mi ne konas lin/ĝin denies acquaintance or familiarity.

— Je kioma horo komenciĝas la prelego? — Mi ne scias.

— What time does the lecture start? — I don't know.

— Ĉu tiu aŭtoro estas bona? — Mi ne konas liajn verkojn.

— Is that author good? — I am not familiar with his works.

In the second exchange, mi ne scias would merely report lack of an answer. Mi ne konas liajn verkojn explains why the speaker cannot judge: the works are unfamiliar.

People can be objects of either verb in different constructions

The simple contrast “people take koni” is helpful but incomplete. A person is the object of koni when acquaintance is meant, yet information about a person belongs with scii and a clause or pri phrase.

Mi konas la direktoron, sed mi ne scias, ĉu ŝi partoprenos.

I know the director, but I do not know whether she will participate.

Ĉu vi scias ion pri la nova najbaro, aŭ ĉu vi jam konas lin persone?

Do you know anything about the new neighbor, or do you already know him personally?

These forms are not competitors for the same complement. Scii ion pri iu packages information as ion and treats the person as its topic; koni iun makes the person directly the familiar entity.

A repair algorithm

Replace English know with a fuller paraphrase.
If the paraphrase is “possess the fact/answer” or “know how,” use scii.
If it is “be acquainted/familiar with,” use koni.
Choose the appropriate complement: ke/ĉu/ki- clause, infinitive, information noun, or familiar entity.
If both seem plausible, state more explicitly what kind of knowledge you mean.

Common Mistakes

Using koni before a fact clause

❌ Mi konas, ke la kunveno estis nuligita.

Incorrect — a ke-clause presents known information and selects scii.

✅ Mi scias, ke la kunveno estis nuligita.

I know that the meeting was canceled.

Using scii for personal acquaintance

❌ Ĉu vi scias nian novan najbaron?

Incorrect for ‘Are you acquainted with our new neighbor?’

✅ Ĉu vi konas nian novan najbaron?

Do you know our new neighbor?

Using koni for an indirect question

❌ Mi ne konas, kial la butiko estas fermita.

Incorrect — the missing knowledge is an answer to why.

✅ Mi ne scias, kial la butiko estas fermita.

I do not know why the shop is closed.

Assuming acquaintance includes every fact

❌ Mi konas ŝin, do mi scias ŝian telefonnumeron.

Faulty inference — knowing a person does not entail knowing that datum.

✅ Mi konas ŝin, sed mi ne scias ŝian telefonnumeron.

I know her, but I do not know her phone number.

Key Takeaways

Choose scii for propositions, answers, known data, and know-how. Choose koni for acquaintance or familiarity with an entity or subject. English know hides this distinction; paraphrase the intended type of knowledge before selecting the Esperanto verb.

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