European languages (such as Germanic and Romance languages) often indicate evidential-type information through modal verbs (Spanish: deber de, Dutch: zouden, Danish: skulle, German: sollen) or other lexical words (adverbials, English: reportedly) or phrases (English: it seems to me).
Alexandra Aikhenvald (2004)[4] reports that about a quarter of the world's languages have some type of grammatical evidentiality.
Laura Mazzoni has since conducted a preliminary study on evidentiality in Italian Sign Language (LIS).
Grammatical evidentiality may be expressed in different forms depending on the language, such as through affixes, clitics, or particles.
For example, Japanese has inferential evidentials and reportive markers that are realized as suffixes on a variety of mainly verbal predicates, and as grammaticalized nouns.
[6] In another example, Eastern Pomo has four evidential suffixes that are added to verbs: -ink’e (nonvisual sensory), -ine (inferential), -·le (hearsay), and -ya (direct knowledge).
In some languages, evidential markers also serve other purposes, such as indicating the speaker's attitude towards, or belief in, the statement.
Using an indirect evidential marker, such as one for hearsay or reported information, may indicate that the speaker is uncertain about the statement, or doesn't want to take responsibility for its truth.
In his dissertation on Nanti, a Peruvian Amazonian language, Lev Michael refers to an example in which a young girl is accidentally burned, and a community member questions her mother about how it happened.
Her mother uses the evidential marker ka which translates to "presumably," to deflect responsibility for the girl's mistake.
This can be seen in the following Turkish verbs: gel-dicome-PASTgel-dicome-PAST"came"gel-mişcome-INDIR.PASTgel-mişcome-INDIR.PAST"obviously came, came (as far as understood)"[14] In the word geldi, the unmarked suffix -di indicates past tense.
The direct past tense marker -di is unmarked (or neutral) in the sense that whether or not evidence exists supporting the statement is not specified.
An inferential evidential indicates information was not personally experienced but was inferred from indirect evidence.
[19] For example, according to Aikhenvald, a given language may use the same element to mark both evidentiality and mirativity, i.e., unexpected information.
[21] This is the case for Georgian (Kartvelian), Turkish (Turkic), Komi-Zyrian (Finno-Ugric), Haida (a language isolate in British Columbia and Alaska), and Ika (Chibchan).
An English example: For instance, de Haan[22][23][24] states that evidentiality asserts evidence while epistemic modality evaluates evidence and that evidentiality is more akin to a deictic category marking the relationship between speakers and events/actions (like the way demonstratives mark the relationship between speakers and objects; see also Joseph 2003).
De Haan (2001)[23] finds that the use of modal verbs to indicate evidentiality is comparatively rare (based on a sample of 200 languages).
Evidentiality is not considered a grammatical category in English because it is expressed in diverse ways and is always optional.
If we are simply assuming that Bob is hungry based on the way he looks or acts, we are more likely to say something like: Here, the fact that we are relying on sensory evidence, rather than direct experience, is conveyed by our use of the word look or seem.
Another situation in which the evidential modality is expressed in English is in certain kinds of predictions, namely those based on the evidence at hand.