A summary of Goidelic developments chapter by chapter of Kim McCone's Towards a relative chronology of ancient and medieval Celtic sound change (1996).

Chapter One: The Phonology and Orthography of the Attested Celtic Languages

I.1 Introduction

Irish Ogam inscriptions date to the 5th and 6th c. C.E.
The Irish manuscript record emerged in the 7th c. C.E.
Church literacy provided the model for vernacular writing.
Ogam is almost certainly based on the Roman alphabet.
Manuscript orthography from the 5th to 12th c. C.E. was based on British Latin pronunciation.
After the 12th c. C.E., the orthography underwent experimental changes.

I.5 Ogam Irish

I.5.1 The Origins of Ogam

Cultural Influences

The earliest attested method of writing Irish is Ogam.
It is written on a line formed by the edge of a stone.
It consists of:
- one to five notches (a, o, u, e, i);
- one to five horizontal strokes to the right (b, l, f, s, n);
- one to five horizontal strokes to the left (h, d, t, c, q);
- one to five diagonal strokes across (m, g, ng, z, r).
It is almost certainly based on the Roman alphabet.
Its twenty signs in four groups of five obviously had a numeric basis.
It was probably devised in the 4th CE.
There was probably already an established Christian community in the south of Ireland at the time.
The Latin-based literacy of Christianity possibly influenced its creation.
Irish colonies were being established in Wales in the 4th CE, providing another possible link to the learning of Latin.
Archaeological evidence shows a material link between Ireland and Roman-based communities at the time.
Cultural contact between these communities would have helped provide the environment and influence for its creation.

Innovations

The alphabetic characters substituted for the Ogam symbols were assigned during the much later manuscript tradition.
The omission of Latin p, and phonetic pairings of d/t and c/q, show innovation with a practical focus on Primitive Irish phonology.
These innovations help show the phonemic structure of Irish of the 4th CE.
The later substitution of alphabetic characters shows deviation from the original phonemic values.

Phonemic Considerations

Bilingual inscriptions from Wales show the transcription of v instead of the substituted f assigned during the manuscript tradition, considering /f/ was unlikely to have arisen from /w/ during the 4th c. C.E (V.2.2).
The later reanalysis was probably due to the historical change found in the initial sound of the name of the letter:
- fern “alder” < *wernā.
The manuscript tradition did seem to recognise a written distinction between c and q even though the latter was lost in speech by the 6th CE (IV.3.4).
There was an obvious phonetic connection between the initials of the names for the letters but a lack of phonemic distinction between velar and labiovelar counterparts:
- coll “hazel” (< *kollo- < *koslo-) for c;
- cert “apple-tree” (< *kʷerto- < *kʷerxto- < *kʷerkʷ-to- < *perkʷ-; II.1.5b) for q.
Since the 6th CE merger of /kʷ/ with /k/, a second letter was needed for this written distinction and q was coincidentally chosen for historical /kʷ/.
Like f, the signs h, ng and z seem unlikely to have been devised to represent the sounds ascribed to them in the manuscript tradition as /h/, /ŋ/ and /z/ were hardly distinct phonemes in 4th or 5th CE Irish.
Their assignment seems to have been a Latin-based cosmetic choice with their name initials being a contributing factor.
Their true values may have been /j/, /ɡʷ/ and /sᵗ/ respectively, or something similar, but this cannot be directly tested due to their lack of attestation on available inscriptions.

Phonemic Developments

For as long as /kʷ/ existed in Irish, so too did /ɡʷ/.
They first dissimilated to /k/ and /ɡ/ respectively before a following rounded back vowel (i.e. /u(ː)/ or /o(ː)/):
- consider the attested dego(s) rather than *dengo(s) “flame”, “fire” < *degw-i-s.
They then rounded a following /a/ and /i/ to /o/ and /u/ respectively (IV.3.4):
- the ⟨q⟩ in qunacanos being a hypercorrection since the distinction with ⟨c⟩ became lost in this environment before lowering occured.
Both finally merged with /k/ and /ɡ/ respectively in the 6th CE (II.1.2) after both raising and lowering (IV.2.1b/c and IV.3.4).

I.5.2

I.6 Old Irish

I.6.1

I.6.2

I.6.3

I.6.4

I.6.5

I.6.6

I.6.7

I.6.8

Chapter Two: From Proto-Indo-European to Proto-Celtic

II.1 Stops

II.1.1

II.1.2

II.1.3

II.1.4

II.1.5

II.2 Fricatives

II.2.1

II.2.2

II.2.3

II.3 Sonants

II.3.1

II.3.2

II.3.3

II.4 Laryngeals

II.4.1

II.4.2

II.4.3

II.4.4

II.5 Vowels

II.5.1

II.5.2

II.5.3

II.5.4

II.5.5

II.5.6

II.5.7

Chapter Three: The Voiceless Labiovelar, Syllabic Nasals, Lenition and the Celtic Family Tree

III.1 The Voiceless Labiovelar

III.1.1

III.1.2

III.1.3

III.1.4

III.2 Syllabic Nasals

III.2.1

III.2.2

III.2.3

III.2.4

III.2.5

III.2.6

III.2.7

III.3 The Gallo-British Hypothesis

III.3.1

III.3.2

III.4 Lenition

III.4.1

III.4.2

III.4.3

III.4.4

III.4.5

III.4.6

III.5 Evidence for Insular Celtic

III.5.1

III.5.2

III.5.3

III.5.4

III.5.5

III.5.6

III.5.7

III.5.8

Chapter Four: Primitive Irish

IV.1 Early Developments

IV.1.1

IV.1.2

IV.1.3

IV.1.4

IV.1.5

IV.2 Umlaut and Other Changes in Vocalism

IV.2.1

IV.2.2

IV.2.3

IV.2.4

IV.2.5

IV.2.6

IV.3 Palatalisation

IV.3.1

IV.3.2

IV.3.3

IV.3.4

IV.3.5

IV.4 Loss of Final Consonants and Vowels

IV.4.1

IV.4.2

IV.4.3

IV.5 Compensatory Lengthening and Syncope

IV.5.1

IV.5.2

IV.5.3

Chapter Five: From Early Old Irish to Middle Irish

V.1 Consonant Groups Arising by Syncope

V.1.1

V.1.2

V.1.3

V.1.4

V.1.5

V.1.6

V.2 Semivowels and Diphthongs

V.2.1

V.2.2

V.2.3

V.2.4

V.3 Voicing of Consonants

V.3.1

V.3.2

V.3.3

V.3.4

V.3.5

V.4 Breaking, Proclisis and Unstressed Vowels

V.4.1

V.4.2

V.4.3

V.4.4

V.5 Changes in the Old Irish Phonemic System

V.5.1

V.5.2

V.5.3

V.5.4

V.5.5

V.5.6

V.6 Middle Irish Developments

V.6.1

V.6.2

V.6.3

V.6.4

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