Ears of corn

"We must also recognise there are real economic reasons why people have played up the issue of the Irish border and the need to have the shibboleth of the Good Friday Agreement."

Labour politician Barry Gardiner being just plain wrong about the Good Friday Agreement. A shibboleth, you'll recall, is a social marker which distinguishes members of an ingroup from members an outgroup:

...the men of Gilead said unto him, Art thou an Ephraimite? If he said, Nay;
Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.

Judges 12

The only function of the shibboleth is to distinguish between groups. The word's intrinsic, specific meaning is unimportant ("The term originates from the Hebrew word shibbólet (שִׁבֹּלֶת‬), which literally means the part of a plant containing grains, such as an ear of corn or a stalk of grain or, in different contexts, "stream, torrent").

The intrinsic, specific meaning of The Good Friday Agreement, in contrast, matters. The Republic of Ireland amended its constitution to remove its territorial claims to the whole island of Ireland. The United Kingdom ended direct rule in Northern Ireland. New agreements were made between Ireland and the UK and between Ireland and Northern Ireland. Watchtowers and border posts came down. People mostly stopped killing one another.

A daft quibble about cereal pronunciation it wasn't.

But Gardiner's use of the word did get me thinking about actual shibboleths. Not only was Gardiner wrong about the Good Friday Agreement itself, which was not a shibboleth, but the Good Friday Agreement precisely destroyed the power of shibboleths that had previously divided Irish people on both sides of the border:

In the BBC documentary series Who Do You Think You Are?, for instance, Graham Norton describes fraught childhood visits to his grandmother’s Belfast home:

I remember once my father got lost [in the Sandy Road area] and we were walking around, and I’d be gabbling on and my father was like, “shut up! Shut up!” Because if anyone heard our voices, you know, we spoke with a southern accent, it would have been trouble.

Dialect blog.

The Good Friday Agreement was all about getting rid of barriers and shibboleths. The global Trumpists, the Brexiteers and the alt-right are all about putting up walls, taking back control of our borders, sorting folk into "them" and "us", taking something as unimportant as skin colour or birthplace and turning it into a shibboleth.

For a long time I didn't understand why these sort of people kept on using this weird stereotypical vocabulary that you never ever hear ordinary folk using in everyday life - "snowflake", "SJW", "cuck", and so on. It doesn't make sense if you assume that these individuals are using language to communicate with others outside their own group. It makes perfect sense if you assume that these words are shibboleths, being used to self-identify as part of the ingroup.

One of the zeitgeisty books of the noughties was a hatchet job on business bullshit titled Why Business People Speak Like Idiots. Clearly there's a gap it today's market for a book called Why The Alt-Right Speak Like Idiots (tl;dr answer: because shibboleths).