Gleasure discussed the evolution of the Present/Future Tense in Scottish Gaelic
He argues that Scottish Gaelic (henceforth, SG) is more conservative regarding phonology than other "Goedelic languages," but in Syntax and Morphology there has been more change than in other languages.
Take the example of Irish, it has 3 simple tenses: past, present, future
In SG, present and future are merged.
This paper aims to explain diachronically the development of this change.
Past Linguists have tried to explain the 'disappearance' of the future tense, e.g. Heinrich
Literary texts and the preservation of a few remnants of the tense distinction suggest that there was once a separation between future and present.
Fraser 1915, first to tackle issue of division of tenses
Gleasure suggests that the reduction of -f- to zero removed the formal difference between the future and the present, and that on occasion the present could be used to express a future action.
O'Rahilly adopted this idea without acknowledgement from Fraser, claiming that the present tense has adopted the old future:
'the future and conditional have been merged in the present and imperfect, respectively, mainly as the result of the silencing of the =f= of the two former tenses.'
dh'innsinn <- dh'innisfinn
'I would tell'
David Greene, claims that a simple phonetic change cannot account for such a large semantic change.
Borgstom attempted to characterize a lack of division in the tenses, by claiming that Norse verbs also make no distinction, but failed mention how Gaelic syntax is influenced by Norse, and why the use of the old present tense, with its predominately future meaning, is not in full accordance with Norse.
Quin: the retention of the old present 3 sing. ending /-idh/ in SG, which meant that bacaidh and the future bacfaidh became indistinguishable as /baki/ was the main factor for the disappearance of the distinction between the tenses.
Gleasure asserts that there is a correspondence with earlier language in Modern SG present/future such as:
modern form: bearidh/-beir 'bears, will bear' 'gabhaidh/-gabh' 'take,will take'
and that this correspondence resembles the the present tense of Old Irish verbs.
Gleasure claims that his cannot be coincidental:
1- Irish could have participated in the Scottish development because some Irish dialects have future particles in the present tense.
2-The usage of the present tense in Irish was once much more common than it is. furthermore, it could express progressive, or continuous tense.
3-There was considerable 'scope' in the early language for a possible merging of the two tenses, present and future. This is true for the copula.
It therefore looks as though there was an early dialectical divergence from Old Irish to Gaelic that catalyzed the loss of tense.