the plain voiced ones, *b *d *ɡ as hypothesized by the usual Proto-Indo-European phonological reconstructions. A forerunner of the theory was proposed by The glottalic theory is a hypothesis that Proto-Indo-European had ejective or otherwise non-pulmonic stops, *pʼ *tʼ *kʼ, instead of the plain voiced ones, *b *d *ɡ as hypothesized by the usual Proto-Indo-European phonological reconstructions. A forerunner of the theory was proposed by the Danish linguist Holger Pedersen in 1951, but he did not involve glottalized sounds. While early linguists such No root contained a sequence of two plain voiced stops: there were no roots of the type *deg, which reflects a common cross-linguistic constraint against roots with two similar stops. No root contained both a voiceless stop and a voiced aspirate: roots of the type *dʰek or *tegʰ were not attested. As the… In… The glottalic theory is a hypothesis that Proto-Indo-European had ejective or otherwise non-pulmonic stops, *pʼ *tʼ *kʼ, instead of the plain voiced ones, *b *d *ɡ as hypothesized by the usual Proto-Indo-European phonological reconstructions. A forerunner of the theory was proposed by the Danish linguist Holger Pedersen in 1951, but he did not involve glottalized sounds. However, it was later realized that the series was unnecessary and that it was generally the result of a sequence of a tenuis stop (*p, *t, *k, *ḱ, *kʷ) and one of the Proto-Indo-European laryngeal consonants: *h₁, *h₂, or *h₃. The aspirate series was removed, but the breathy voiced consonants remained. === Problems === There are several problems with the traditional reconstruction. Firstly, the rarity of *b is odd from a typological point of view. For example, Robert Blust showed that Kelabit, a language of the Sarawak highlands in Borneo, has a system of stops consisting of Postulating the voiceless stops as aspirated finds support in helping to explain Grimm's Law, with these purported now-aspirated stops (*pʰ *tʰ *kʰ) evolving into Proto-Germanic ɸ θ x. This would also be typologically similar to one of the more notable evolutions from Ancient to Modern Greek (with φ, θ, and χ respectively). === Consequences === The phonation system proposed by the glottalic theory is common among the world's languages. Moreover, the revised system explains a number of phonological peculiarities in the reconstructed system. Kortlandt also proposes word-final glottalization in English to be a retention and derives features such as preaspiration in Icelandic and Faroese and sporadically in Norwegian and certain instances of gemination in Swedish and High German from preglottalization as well. In both Latin (Lachmann's law) and Balto-Slavic (Winter's law), vowels are lengthened before a "voiced" consonant. It is the same behaviour that vowels exhibit before Proto-Indo-European laryngeals, which are assumed to have included a glottal stop. If the system were typologically common, as proposed by the glottalic theory, it might be expected to be stable and so be preserved in at least some of the daughter languages, which is not the case: no daughter language preserves ejective sounds in places that the theory postulates them. Its proponents respond that if Proto-Indo-European did not have true ejectives but some less stable kind of glottalic consonant, their loss would be more understandable, but that undercuts many of the original motivations of the glottalic theory, which are based on ejectives (rather than glottalized consonants) and on the idea of a typologically natural (and so stable) system. Kortlandt also asserts that the change from aspirated to plain voiced stops, which is likewise required as an independent change in numerous Indo-European branches under the traditional model, is not attested elsewhere and is typologically suspect. That, he argues, is typologically more common than voiced aspirates without voiceless counterparts: Schirru has also suggested that the voiced aspirated stops could be better analyzed as having the feature [+slack vocal folds] or [−stiff vocal folds]: == Frederik Kortlandt == As mentioned above in "Direct and indirect evidence", Frederik Kortlandt in particular has argued for these traces of glottalization being found in a number of attested Indo-European languages or the assumption of glottalization explaining previously known phenomena, which lends the theory empirical support: Direct Sindhi reflects the non-aspirated voiced series unconditionally as implosives. features such as preaspiration in Icelandic and Faroese and sporadically in Norwegian and certain instances of gemination in Swedish and High German === Problems === Arguably, the minority status of most of the languages which provide the allegedly-certain direct evidence for the theory may be a rather large problem. Also, it is somewhat disputed that either Lachmann's law or Winter's law is real though this dispute is a result of assuming no glottalization in Proto-Indo-European. If Proto-Indo-European once showed glottalization, this circumvents the dispute by not requiring the assumption that we are dealing with an example of a sound law that affects deep phonological structure. Instead, we are dealing with an example of a cross-linguistically common allophonic variation like the VCʼV~VʔCʼV~VːCʼV shown in Quileute. However, it still remains that allegedly-certain direct evidence is absent from any majority Indo-European language except Latvian and two pieces of indirect evidence; the operation of "Lachmann's law" and "Winter's law", have become obscured by subsequent phonological developments in Romance and Balto-Slavic. This is the same as the compromise viewpoint to see the original formulation of glottalic theory, with ejective stops, as representing an earlier stage in the history of Proto-Indo-European, which would have undergone a period of internal evolution into a stage featuring unstable voiced glottalized stops before it branched out into the daughter languages.