I may have fallen foul of a modern assumption... I took for granted that "casting the runes" was a proper old method of divination. But scouring the ArM5 materials I can't see any references to in-period or ancient divinatory practices including the casting of runes.
A few sessions of internet research have shown nothing to suggest a real-word historical tradition of specifically using runes in divination.
So it looks like more of a modern new-age affectation.
Cleromancy (The Mysteries Revised Edition) is the art of casting lots and that looks to be about the closest match.
Anyone know anything more about the casting of divinatory runes?
It is not entirely a modern conceit; there are genuine period references to blótspánn, or "sacrifice-chips". For example, in the Ynglingasaga by Snorri Sturluson, King Granmar receives a negative judgement from a blótspánn at Uppsala. However, it is not clear that these were runic divinations rather than simply casting of lots.
Tacitus in his Germania gives an account of divination by the Germanic people, which is generally considered to be using runes to predict the future.
They cut off a branch of a nut-bearing tree and slice it into strips; these they mark with different signs and throw them completely at random onto a white cloth. Then the priest of the state, if the consultation is a public one, or the father of the family if it is private, offers a prayer to the gods, and looking up at the sky picks up three strips, one at a time, and reads their meaning from the signs previously scored on them. (Germania 10)
This seems to suggest that runes may have been inscribed on the lots. However, this account describes practices of pre-Norse people (Tacitus was writing in the 1st Century) and many hundreds of years pass between his account and the period of the sagas where we know blótspánn were used. Whether or not these chips were inscribed with runes is not clear.
Divination was considered a woman's art by the Norse, and the runes at the time were not considered as magical as many people see them today- it would be like casting a divination using something between the alphabet and Chinese characters in terms of the amount of meaning they carried, Remember that 20 some runes could not begin to carry all of the meanings you would need for a language, but on the other hand they were clearly assigned more meaning that simple sound association.
Given the number of divinations done over the length of time we are talking about I'm sure it happened at some point, on the other hand the women's mysteries had a tendency to not be documented, so how much it was done is literally a question of guessing.
The contemporary records of Norse casting of lots does not specify the sex of the practitioner, and Tacitus's account (while not Norse) implies that it was performed by men. While it is true that divination is considered a female art in Norse culture; we have no evidence that women divined via rune-casting.
With respect to the individual runes not constituting a language -- we don't know that the 'lots' used in this divination were each inscribed with just a single rune. Each could have had a word or sentence, perhaps designed specifically for the question in hand in a manner similar to practices found elsewhere in Europe (e.g. scapulomancy). But that is conjecture.
The runes were certainly considered to have a magical function, as attested multiple times in the sagas -- or at least, as a means to effect magic if not magical in and of themselves.
True, but if they have words or sentences written in runic then it isn't rune casting in the sense of what is visualized and practiced today either. The difference would be the difference between reading messages on a magic eight ball(words and sentences) versus grabbing scrabble tiles (modern rune casting)
Good info all through, but pulling this line out...
Yes, I think that's where I was going, somewhat clumsily. I watched the YouTube video you referenced and Crawford's explanation does sound very much like a casting of lots rather than runes providing some inherent powers of divination.
And I think there's a view of modern rune casting, as @silveroak characterises, as throwing fancy scrabble tiles down, and I think that's the image I was struggling with as reflective of in-period divination.
The concept actually of creating lots, chips, or blótspánn with words or phrases (in the runes, of course) feels more atmospheric to me - and that's what I'm really after.
To model it, it's a form of Cleromancy, but the flavour comes in via the addition of runic words or phrases to the lots that are cast. I think I'm going to go with that.