1) Variability is more common in language.
2) You can find variability in many different areas such as, Geographical (Dialects), Historical and Social contexts (Registers, Formality, Grammar, etc).
3) We can observe their grammar, phonetics, pronunciation, accent etc.
4) I don’t think it is unreasonable because if languages are variable, it means that they change constantly. So, it’s more reasonable to study diachronic linguistics to observe the looks and changes from one period to another, rather than studying the phonological aspects of a language at a stated time.
5) No, it is not abnormal because every language constantly changes, it wuold be abnormale if it woudn’t change and evolve during centuries.
6) Some non-linguistics and many linguistics think that the typical “dequeismo” or for example, using the word “dao” instead of the verb dado, are errors in spanish language usage.
7) Milroy uses scare quotes to indicate that he does not accept the term. He does this because he is expressing non-professional ideas which he does not agree with.
8) Eventhough it doesn’t have the institutional support that a standardized dialect has, it has its own vocabulary and an internally consistent grammar and syntax; and it may be spoken using different accents, this doesn’t mean that it is incorrect or inferior.
9) The second system is certainly more regular than the first one, it isn’t considered as standard because the terms “hisself” and “theirselves” are not commonly used because they are not correct in grammatical terms. We can affirm that the reflexive pronouns in the first column are accepted as grammatically “normative”.
10) I think that this is due to the extreme variability of spoken language in context. If we were to attempt to base our theories of change (in languages) on situated speech, we would find that most people don’t tend to follow grammatical rules and often use colloquialisms, which lead to the destructuralisation of language. We can also refer to the fact that everyone has their own personal speech patterns (idiolects).
11) Even though there are formal written rules, we must also keep in mind that there are always exceptions to these rules, and that there is a tendency to overlook them in the colloquial variety. For example the sentece “he ate the pie already” might be considered as acceptable in colloquial speech, however in a formal context it would be better to say “he has already eaten the pie”.
12) A descriptive grammar looks at the way a language is actually used by its speakers and then attempts to analyse it and formulate rules about the structure. Descriptive grammar does not deal with what is good or bad language use; forms and structures that might not be used by speakers of Standard English would be regarded as valid and included. It is a grammar based on the way a language actually is and not how some think it should be. On the other hand, a prescriptive grammar lays out rules about the structure of a language. Unlike a descriptive grammar it deals with what the grammarian believes to be right and wrong, good or bad language use; not following the rules will generate incorrect language.
(http://www.english-for-students.com/Descriptive-and-Prescriptive.html)
13) “Solidarity constraint” means that society has an effect on the way language changes, including cultural norms, expectations, and context. While “Prestige motivation for change” differs between groups separated by certain social variables, such as ethnicity, status, gender, education, age, as the use of a language varies from place to place (dialect) and among socio-economic classes. We can say that “prestige motivation for change” and the “solidarity constraint” are opposed due to the fact that the first is linked to the notion of wanting to stand out and indicate a superior social status, while the second is a collective movement, related to the idea of fitting in socially.
14) Post-vocalic /r/ in New York
Many of us who speak English as a native language pronounce words like darling, far, bore or near the same as we write them: with vowel followed by r in the same syllable. But there are many other English speakers who do not pronounce the r - sound in this place (called ‘postvocalic r’) - although they have the sound everywhere else, like at the beginning of a word. Linguists use the classy terms rhotic and non-rhotic for these two pronunciations.
In some people’s speech this ‘dropped’ r reappears when the word is followed by a vowel, so you sometimes hear nevah but never again. Such speakers occasionally go on to insert an r where it doesn’t belong, and say sofa but sofer and chair .
Looked at geographically, American speakers who most commonly drop the r (in what follows we’ll occasionally call this the ‘r-less’ pronunciation) are those from Eastern New England and parts of the South, particularly the coastal area where the old ‘plantation’ culture once existed. It is also part of Black English Vernacular speech. Until recently, dropping the r was part of New York speech as well, though more and more New Yorkers seem to be perceiving it as ‘vulgar’ and avoiding this pronunciation. Even though there is no officially recognized ’standard’ English in the U.S., ‘r-speakers’ are clearly an overwhelming majority, something you hear reflected in the mass media.
British speakers today whose speech is closest to standard British English (called ‘Received Pronunciation’) do not pronounce r after vowel. Postvocalic r was still regularly pronounced in English speech back in Elizabethan times, and it was around that time (l6th century) that the ‘r-less’ pronunciation started spreading across much of England. It did not spread as far as Ireland and Scotland, which is why we hear the ‘r’ pronunciation from the Irish and the Scots today. Many of the original immigrants to the colonies were from Scotland and Ireland, although at the time of settlement most English speakers were still pronouncing r after vowel too.
http://www.pbs.org/speak/seatosea/americanvarieties/southern/dahling/
15) The change from long ā to ō in some dialects of English.
The father-bother merger is a merger of the Early Modern English vowels /ɑː/ and /ɒ/ that occurs in almost all varieties of North American English (exceptions are accents in northeastern New England, such as the Boston accent, and in New York City). In those accents with the merger father and bother rhyme, and Kahn and con are homophonous as [kɑn]. Unrounding of EME /ɒ/ is found also in Norwich, the West Country, the West Midlands and in Hiberno-English, but apparently with no phonemic merger.
16) The place and degree of palatization varied in order to differentiate the meaning between the word doublets.
17) Language changes could be compared to darwin’s theory of evolution. He adfirmed that in every population there is variation, but this would be better understood by using his words: “In a world of stable populations where each individual must struggle to survive, those with the "best" characteristics will be more likely to survive, and those desirable traits will be passed to their offspring. These advantageous characteristics are inherited by following generations, becoming dominant among the population through time. This is natural selection.”
18) “All kinds of language change can basically be assigned to one of two types: either the change is caused by a structural requirement of the language — this is internally motivated change — or it does not in which case one speaks of externally motivated change.
Internally motivated change usually leads to balance in the system, the removal of marked elements, the analogical spread of regular forms or the like. As language consists of various modules on various levels, a change in one quarter may lead to an imbalance in another and provoke a further change.”
(http://www.uni-due.de/SHE/HE_InternalExternal.htm)
19) The terms are often found in the same paragraph because the theory of lexical diffusion is opposed to the Neogrammarian hypothesis. As Milroy explains, lexical diffusion (a theory proposed by William Wang in 1969) refers to the fact that all sound changes derive from a variation of a single word or a small group of words that later affects other words with similar characteristics, but don’t necessarily have an effect on all words that they potentially could do. The Neogrammarian hypothesis states that a given sound change applies to all words with related features simultaneously. Milroy tells us that sound changes have normally been observed to spread gradually through the lexicon (lexical diffusion), and that there is no evidence to support the Neogrammarian assumption.
20) A social norm is the sociological term for the behavioural expectations and cues within a society or group. They have been defined as “the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes and behaviours. These rules may be explicit or implicit. The social norms indicate the established and approved ways of doing things, of dress, of speech and of appearance. These vary and evolve not only through time but also vary from one age group to another and between social classes and social groups.
http://en.wikipedia.org/wiki/Norm_(sociology)
With regards to childish errors in language, we can say that children often make mistakes because they do still ignore formal written rules and this is due to their lack of knowledge of possible linguistic irregularities (the use of irregular past participles for example).
A slip of the tongue is an accidental and usually trivial mistake in speaking, usually the transposition of initial consonants in a pair of words (known as spoonerism).