I am sure that this has been asked before, but I was wondering what the rules and how common it is for adjectives to become verbs in Esperanto. I can't remember where I saw it, but as an example, I saw that "The sky is blue" can be translated as "La ĉielo estas blua" or as "La ĉielo bluas." The comment about this mentioned that this was very common in Esperanto and often preferred. I am also using Duolingo to learn Esperanto, and I asked a similar question on their forum about a sentence and I was told that I should avoid making sentences that turn adjectives into verbs because it is usually incorrect, mostly used poetically, and somewhat frowned upon in the Esperanto community. I guess I just wanted to get more Esperanto speakers opinions.

Aargh, you just opened the Pandora's box of E-o! Your question boils down to the subject called "word construction", how words are constructed in E-o. In E-o there are three basic rules:

1) The Zamenhof statement, which says that all suffixes can also be treated as words.
2) The principle of Necessity and Sufficiency (Neceso kaj Sufiĉo) by René de Saussure.
3) The Saussure-an statement of "the word character" by René de Saussure.

The first rule is self-explanatory. The second one says in essence, that don't pile too many suffixes and use the simplest one, e.g. a writing is skribo, not skribaĵo. The third rule is the hardest to grasp.

"The word character" means, that every word root (radiko) has a substantive-like, adjektive-like or verb-like character. If the ending matches this character, the whole word is pleonastic, redundant, otherwise the ending will transform the root to a new word. For instance homo, sana and skribi are pleonastic (the roots have substantive-like, adjektive-like resp. verb-like characters), but homa, sani and skribo are new words, malsamelementaj vortoj (the characters of the roots don't match the endings).

This has lead to the (in)famous broso kontraŭ kombilo debate. As verbs brosi and kombi both mean to brush, to comb, but as substantives they mean different things:

• broso: a brush
  
• kombo: brushing (the action)

The reason is, that the roots have different characters. bros/ has a substantive-like character, while komb/ has a verb-like character. As verbs brosi is a new word, while kombi is pleonastic. As substantives the situation is viceversa, broso is pleonastic and kombo a new word.

Thus the action is brosado resp. kombo, and the tool is broso resp. kombilo.

You might ask, what all this has to do with adjektives, which are turned to verbs, e.g. blua → blui. Well, there are three verb endings: -i, -igi and -iĝi. Because of the word character only adjektives can be turned into all three verb types:

• blui: to be blue
  
• bluigi: to make blue
  
• bluiĝi: to become blue

There are only few substantives, which can be turned into all three verb types, if at all.

A related question is, that people can perceive the roots to have a different character. My favourite is mort/. I perceive it as a state, and thus for me

morti: esti morta (to be dead)
mortigi: finigi vivon, igi morta (to kill)
mortiĝi: ĉesi vivi, iĝi morta (to die)

But this is incorrect, because mort/ is defined as a verb-like root:

morti: ĉesi vivi, iĝi morta (to die)
mortigi: finigi vivon, igi morta (to kill)
(mortiĝi: la formo ne estas uzata)

See another thread here in Lernu.

My take on your question is, that while La ĉielo bluas sounds more poetical, it's usable. However I would hesitate to such turning adjektives into verbs to very few established ones: some colours, plibonigi etc.

HTH

Wow. I make up words all the time and changing the forms of words is one of my favorite things to experiment with. To be clear, however, I also don't have many people to try out these experiments out with, so I can't say how successful they are...

I have never heard these rules about words having base characteristics or anything like that (the concept described for morti/mortigi/mortiĝi makes perfect sense to me and, in fact, is something I kind of took for granted). The idea that the words can't be as flexible as the people that use them irritates me, but if these rules exist, I should at least know them! Where do you find this information and how can I find out which words have which characteristics?

The critics at Duolingo have over-generalised from the particular case of colour description.

Whilst an analysis of any substantial corpus of Esperanto would undoubted reveal many more instances of colour words as adjectives rather than verbs, the relative instance of the parts of speech would not be so skewed with other words whose dictionary entry starts with the adjective form.

Part of the charm of Esperanto is the flexibility in the matter of parts of speech and the guessability of the meanings.

Whilst English also offers considerable freedom to use its words as different parts of speech, there are greater restrictions and the meaning is not always what you might imagine (eg 'to moon' is not guessable from 'moon' and 'lunar' has to be learnt separately from 'moon').

Whilst blui imposes little extra meaning over esti blua, sometimes the simple verbigo of adjectives introduces a different notion.

'Li rapidis for' doesn't mean he is always rapida.

By the way, I wouldn't get too bogged down in the grammarians' theories of Esperanto word formation.

Nobody speaks in roots, we speak in words (ie roots plus a grammatical ending). So the idea that the roots themselves have a grammatical form is clearly an abstract construct.

Obviously you have to know what is the meaning of the base form from which the meanings of the other parts of speech are derived.

Knowing that 'tajloro', for example, is a person and that 'instrui' means 'to teach' is essential to guide you to 'tajlori' and 'instruisto', but to say that 'tajlor' is a noun and 'instru' is a verb is a theoretical leap, and it's an even greater theoretical leap to say that the supposed grammatical character of the root is unchanging irrespective of context.

'Manĝ' is assumed to be a verbal root. But has 'matenmanĝi' acquired its meaning from manĝi, or from matenmanĝo?

I should also add that there are special cases that defy the grammatical theoreticians.

Is 'korekt a verb or an adjective?

According to the theory (single grammatical characters of roots). If 'korekt' is a verb 'korekta should mean corrective, not the well-established meaning of correct.

If 'korekt' is an adjective then 'korektigi' should mean to correct, not to get corrected (by someone else)

If 'plant' is a verb, then why does 'planto; mean a plant rather than a plalnting The theoreticians presumably would say "Oh we got that one wrong originally, 'plant' is a noun".

Esperanto is more pragmatic in its word formations than the theoreticians would have it.

In the end its the usage of words that gives meaning, not abstract notions about roots.

Right, I wouldn't necessarily say always follow the grammatical structure given to you. The real judge should be whether others can understand you. That's my approach to english as well - used to be a total grammar nazi when I was growing up, until I realized that communication is the point of language and as long as you can do that effectively, it's fine. Grammar is more about basic function and conventions.

That being said, these grammar rules for word formation that I don't know will tell me what phrasing is more conventional (as a wanna-be translator, this comes in particularly handy for translating dialogue), so that is useful. But although I do want to know the rules, it does remove a lot of the creativity and one of my favorite things about the language, so I'll probably stick with anything that works well for me as long as I am understood. I would recommend that to others as well, as a general principle, but I wanted to reserve that advice until after I understood the rules that I was shirking...

Don't shoot the messenger!

I stumbled upon this vortfarado myself some time ago and was guided to read La Saussure-a konstato. I barely understood it. As I said, I perceived mort/ as a state (a root with a noun-like character) and thus morti, mortigi and mortiĝi made sense to me. I was shot down with broadside salvos.

It is true, that the community defines the meaning of the words, but in order to make yourself understood you must know, what the words mean for the most speakers. So if I say, "Mia bopatro mortiĝis antaŭ du jaroj", I might be understood, but it may cause confusion and lag in communication. The base meaning, the word character can be seen in the first form of any dictionary entry, e.g. look at PIV, the form morti is the first one for that entry.

As Sudanglo points out there are words with two characters (korekt/) and some roots are perceived otherwise nowdays (plant/). While there are people, who say, that La Fundamento estas netuŝebla, i.e. it is a never-changing canon, that is simply not true. E-o evolves, as it should, but La Fundamento works like a drift-anchor making the evolution slow, so that everybody stays onboard.

Metsis:Don't shoot the messenger!

I'm not; I promise! Sorry if I came across that way.

Metsis:I stumbled upon this vortfarado myself some time ago and was guided to read La Saussure-a konstato. I barely understood it. As I said, I perceived mort/ as a state (a root with a noun-like character) and thus morti, mortigi and mortiĝi made sense to me. I was shot down with broadside salvos.

Oh, don't be shot down! Really, it makes perfect sense to me. I'm sure I can't be the only one. I didn't even realize I was technically being creative on that one!

On the other hand, I tend to interpret Esperanto roots based on their noun form (or the concept that their noun form would represent if it were turned into a noun). The idea that words can so easily change forms reinforced the idea, to me, that they were MEANT to change forms. Changing the form was ALWAYS acceptable for EVERY word (I used this argument at my local Esperanto meetings - back when I bothered attending them - to argue that technically "kialo" was interchangeable with "ĉaro". That was a fun debate...). And the fact that you could drop the "o" at the end of nouns in creative works like poetry also reinforced the idea that every root in Esperanto is essentially a noun. You don't have the word "mort'" being used creatively to mean "to die", after all - even though the root is supposed to have verb-like characteristics. It still means the noun - death.

Metsis:It is true, that the community defines the meaning of the words, but in order to make yourself understood you must know, what the words mean for the most speakers. So if I say, "Mia bopatro mortiĝis antaŭ du jaroj", I might be understood, but it may cause confusion and lag in communication. The base meaning, the word character can be seen in the first form of any dictionary entry, e.g. look at PIV, the form morti is the first one for that entry.

As Sudanglo points out there are words with two characters (korekt/) and some roots are perceived otherwise nowdays (plant/). While there are people, who say, that La Fundamento estas netuŝebla, i.e. it is a never-changing canon, that is simply not true. E-o evolves, as it should, but La Fundamento works like a drift-anchor making the evolution slow, so that everybody stays onboard.

Definitely. Following grammar rules does help things stay understandable most efficiently, and even if the rule doesn't seem to get much use, I still think it's important to know - hence why I still want to look into it. Yes, I think it's important to take grammar rules with a grain of salt, but only as long as it's still effective communication. Creativity is great, but it's true that if it moves too fast not everyone can keep up and we end up with varying dialects of a language that used to be understandable by all groups. Dialects can still be close enough to be understood, but they can also vary in fundamental ways and become incomprehensible, and with a language spread out as much as Esperanto, this is an even more pressing concern. It's not that grammar isn't important, just that I strongly oppose the "La Fundamento estas netuŝebla" idea, and they push so hard... But again, I was hesitant to say outright "oh; don't worry about it! The rule doesn't matter!" because in some cases, the rules really do matter. And they are always important to be aware of, even if you choose to ignore them. If your choice to ignore it was truly a bad one, you will find out quickly enough anyway.

On a side note, it probably doesn't help that I first came across the "netuŝebla" idea when I was researching riism and it was the main argument for not using it. Don't make the language better because someone from a different time period wasn't psychic enough to think of it? Really?? Of course, I recognized that "better" was an opinion, but it actually took some digging at the time to find any real reasons to oppose it, so that one really made me mad...

This dialect-less-ness puzzles me a little. Many people speak a dialect as their first language, and only later they learn the standardised language. Usually the more education you have, the more dialect-free you speak. I think, this applies to all languages.

Since E-o is said to be dialect-free, how do you express dialects? For instance ,say, the tv-series Heimat would be subtitled or dubbed to E-o. Could this "estas blua" vs. "bluas" pass for a dialectal difference?

Most communities, if not all, have unwritten social rules. For example, in England you do not jump a queue, but rather wait your turn, also if someone bumps into you in the street you say sorry even though it's the other party's fault.

In the Esperanto speaking community it has long been a social rule that you do not pepper your Esperanto with regionalisms (syntactic or semantic), nor with eccentric or personally preferred deviations from the standard. The language is after all for international communication.

It is no mystery therefore that Esperanto doesn't really have dialects.

Bluas versus estas blua can not really be considered a dialectal variation. I am not aware that this shows any preponderance geographically or within any social class.

The whole issue of representing in translation what the linguists call register presents special demands on the imagination of the translator.

Since there will not be any corresponding reality in Esperanto usage such as might exist in a national language, the sub-titling of any national language TV programme involving a register problem will necessitate the invention of some non-standard usage that might give the requisite flavour.

This is not too dissimilar to the invention of alien language in Science Fiction films. Nobody knows how aliens actually speak.

This lack of correspondence with reality does not bother the audience if imaginatively done. And in the same way the subtitling in Esperanto of dialectal usage in the original may also succeed, if imaginatively done.