The reference works divide over whether this particle has a core meaning. BDB and Gesenius-Kautzsch-Cowley treat it as a subordinating conjunction glossed "that, for, when", and BDB admits an asseverative sense only with the explicit caveat that it is doubtful whether the particle carries that force in all the passages for which scholars have invoked it. HALOT reverses the ordering after Muilenburg (HUCA 32, 1961), listing the demonstrative and asseverative particle first and the conjunction second; the eighteenth-edition Gesenius follows suit, and Waltke-O'Connor §39.3.4e goes furthest, reclassifying the word as an emphatic clausal adverb. Joüon-Muraoka is more cautious, allowing an asseverative use only after oath formulas, in the apodoses of conditionals, and in predicate-fronted clauses, and warning at §164g against a vague appeal to emphasis, while Muraoka §170d.α distinguishes causality between real-world states of affairs from the particle presenting the evidence for an assertion. Williams-Beckman lists ten functions without ranking them; van der Merwe, Naudé and Kroeze §40 organize the uses by clause position and separate fact-based, action-based, and knowledge-based causality. Comparative Semitists derive the word from Proto-Semitic *kī, an extension of the deictic base *ka (Hasselbach, JAOS 127; Rubin, Studies in Semitic Grammaticalization), with Akkadian kī and kīma, Ugaritic k and ky, and Phoenician k as cognates; Aramaic has no productive reflex and uses דִּי and אֲרֵי instead, which is why the Targumim render the Hebrew particle with אֲרֵי. The modern debate runs from Muilenburg's deictic-emphatic thesis and Schoors (OTS 21, 1981) through Bandstra's 1982 Yale dissertation, which correlated clause position with function (causal clauses follow the main clause about 95 percent of the time) and judged the alleged emphatic use unrecognized before the modern era, to Muraoka's restrained defense (Emphatic Words and Structures, 1985, 164), Aejmelaeus's causal-explanatory reanalysis (JBL 105, 1986), Follingstad's monosemic account of the particle as a marker of viewpoint shift within Mental Space Theory (2001), Park's stand-alone nominalization proposal (JSS 61, 2016), and Locatell's prototype-polysemy network (Stellenbosch, 2017), which sets causality as the prototype and distributes the uses across content, epistemic, speech-act, and metalinguistic domains after Sweetser. Aejmelaeus adds external evidence: the Septuagint translators overwhelmingly preferred the subordinating ὅτι to the coordinating γάρ, even where Hellenistic Greek would favour γάρ, which implies they heard the Hebrew particle as a subordinator rather than an emphatic. Dahood's maximalist emphatic and precative readings in the Anchor Bible Psalms are now generally regarded as overreach. In casuistic law, Alt's 1934 observation that this particle marks the principal protasis while אִם marks the sub-case has been broadly confirmed (Westbrook; Jackson; Bartor). Cynthia Miller argues against recognizing a formal recitative category. Distribution is uneven: Bandstra counted 72 percent of Psalms occurrences (318 of 443) as causal against 52 percent in the Pentateuch (536 of 1037), and the particle retreats through Late Biblical and Qumran Hebrew before disappearing as a productive conjunction in Mishnaic Hebrew, where שֶׁ־, מִפְּנֵי שֶׁ־, אִם and כְּשֶׁ־ take over its functions.