Irrealis markers are characterized by the rampant heterogeneity of their distributional patterns and by the tendency to appear as portmanteau morphemes encoding other grammatical categories (e.g. person). These and other characteristics may find an explanation in diachronic terms, by taking into account the sources from which irrealis markers derive. In this paper, the most frequent sources of irrealis markers are identified by means of a diachronic‐typological survey based on a 100–language sample: these include lexical verbs such as ‘go’, ‘want’ or ‘be’, former subordinate clauses that come to be used as main clauses through insubordination and deictic expressions that refer to distant elements. Considering the diachrony of irrealis markers allows us to explain some of their properties such as, among others (i) their distribution across the domain of non‐actualized situation types, (ii) the primacy of certain non‐actualized situation types that happen to work as bridgeheads in the diachronic development from the source to the target irrealis marker, (iii) the frequent co‐encoding of person and reality status by means of the same markers, and (iv) the existence of ergativity splits involving irrealis clauses. The diachronic‐typological survey conducted in this paper has some implications on the debate on the validity of reality status as a grammatical category with two opposite values of realis and irrealis: it will be argued that the diachronic scenarios leading to the emergence of irrealis markers are not substantially different from those known from the literature on the emergence of modal markers, which makes reality status superfluous as an independent grammatical category.

中文翻译：

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通往Irrealis的路线

Irrealis标记的特征在于其分布模式的普遍异质性，以及倾向于以编码其他语法类别（例如人）的Portmanteau语素出现的趋势。通过考虑无rerealis标记源自的来源，这些和其他特征可以用历时的术语找到解释。在本文中，通过基于100种语言样本的历时性语料调查，确定了最常见的irrealis标记来源：这些词包括动词，例如“ go”，“ want”或“ be”，以前的从句通过不称从属和代表遥远元素的deictic表达式被用作主要从句。考虑到irrealis标记的历时性，我们可以解释其一些特性，例如，除其他外（i）它们在非实际情况类型领域中的分布，（ii）某些非实际情况类型的首要地位，恰好在从源头到目标无rerealis标记的历时发展中充当桥头堡；（iii ）通过相同的标记对人和现实状态进行频繁的共编码，并且（iv）存在涉及不规则子句的能动性拆分。本文进行的历时性调查对关于现实状态作为一种具有真实和反义两个相反值的语法类别的有效性的辩论有一些启示：将认为导致历时性标记出现的历时情境是与关于模态标记出现的文献中所知的没有实质性的不同，