Esperanto was conceived as a language of international communication, more precisely as a universal second language. Since publication, there has been debate over whether it is possible for Esperanto to attain this position, and whether it would be an improvement for international communication if it did. There have been a number of attempts to reform the language, the most well-known of which is the language Ido which resulted in a schism in the community at the time, beginning in 1907.
Since Esperanto is a planned language, there have been many, often passionate, criticisms of minor points which are too numerous to cover here, such as Zamenhof's choice of the word edzo over something like spozo for "husband, spouse", or his choice of the Classic Greek and Old Latin singular and plural endings -o, -oj, -a, -aj over their Medieval contractions -o, -i, -a, -e. (Both these changes were adopted by the Ido reform, though Ido dispensed with adjectival agreement altogether.) See the links below for examples of more general criticism. The more common points include:
- Esperanto has failed the expectations of its founder to become a universal second language. Although many promoters of Esperanto stress the few successes it has had, the fact remains that well over a century since its publication, the portion of the world that speaks Esperanto, and the number of primary and secondary schools which teach it, remain minuscule. It simply cannot compete with English in this regard.
- The vocabulary and grammar are based on major European languages, and are not universal. Often this criticism is specific to a few points such as adjectival agreement and the accusative case (generally such obvious details are all that reform projects suggest changing), but sometimes it is more general: Both the grammar and the 'international' vocabulary are difficult for many Asians, among others, and give an unfair advantage to speakers of European languages.
One attempt to address this issue is Lojban, which draws from the six populous languages Arabic, Chinese, English, Hindi, Russian, and Spanish, and whose grammar is designed for computer parsing.
- The vocabulary, diacritic letters, and grammar are too dissimilar from the major Western European languages, and therefore Esperanto is not as easy as it could be for speakers of those languages to learn.
Attempts to address this issue include the younger planned languages Ido and Interlingua.
- Esperanto phonology is unimaginatively provincial, being essentially Belorussian with regularized stress, leaving out only the nasal vowels, palatalized consonants, and /dz/. For example, Esperanto has phonemes such as/x/, /ʒ/, /ts/, /eu̯/ (ĥ, ĵ, c, eŭ) which are rare as distinct phonemes outside Europe. (Note that none of these are found in initial position in English.)
- Esperanto has no culture. Although it has a large international literature, Esperanto does not encapsulate a specific culture.
- Esperanto is culturally European. This is due to the European derivation of its vocabulary, and more insidiously, its semantics; both infuse the language with a European world view.
- The vocabulary is too large. Rather than deriving new words from existing roots, large numbers of new roots are adopted into the language by people who think they're international, when in fact they're only European. This makes the language much more difficult for non-Europeans than it needs to be.
- Esperanto is sexist. As in English, there is no neutral pronoun for s/he, and most kin terms and titles are masculine by default and only feminine when so specified.
There have been many attempts to address this issue, of which one of the better known is Riism.
- Esperanto is, looks, or sounds artificial. This criticism is primarily due to the letters with circumflex diacritics, which some find odd or cumbersome, and to the lack of fluent speakers: Few Esperantists have spent much time with fluent, let alone native, speakers, and many learn Esperanto relatively late in life, and so speak haltingly, which can create a negative impression among non-speakers. Among fluent speakers, Esperanto sounds no more artificial than any other language. Others claim that an artificial language will necessarily be deficient, due to its very nature, but the Hungarian Academy of Sciences has found that Esperanto fulfills all the requirements of a living language.