The ‘mistakes’ in these sentences would be more or less obvious to people
who concern themselves with such things, with the possible exception of
the last two examples. In those cases, many academics probably would
argue that the noun data must be used as a plural, with a plural verb (The
data do not support your conclusion); particularly hardline prescriptivists
would be sure to point out that things are put into a pocket.
For non-linguists, grammaticality is used in a much broader and fluid
sense. It encompasses the spoken and written languages, and extends to
matters of style and even punctuation. However, most important
differences between the two approaches to grammar have to do with the
concept of socially motivated grammaticality.
Pinker uses the example of a taxicab to illustrate the distinction. As it is
a useful illustration I have adapted it here: “The Taxicab Maxim: A
taxicab must obey the laws of physics, but it can flout the laws of the state
of Michigan (or Massachusetts, or London, etc.)” (Pinker 1994b). To take
a closer look at this idea, please consider the sentences in Table 1.1, and
the way they are evaluated.
The last four examples are where the linguist and the non-linguist
usually part ways. As any of these sentences could be – and are – heard in
casual conversation every day on American streets, they are grammatical.
A prescriptivist will take issue with the way the verbs have been used but
even a prescriptivist could not claim that the meaning was unclear – we
know exactly what it means if we hear somebody say my sister is taller
than me. The hardline prescriptivist would say that the correct usage is my
sister is taller than I. Formulated this way, the speaker would not be seen
as well-spoken, but as odd or pretentious or perhaps, a non-native speaker.
Table 1.1 Grammaticality judgment comparison