A bit more info on the origins of this.
The original that David draws on is a hypothetical proposed by H.L.A. Hart in 1958. The original is looking specifically at law and the fact that even for 'settled meaning' of a term or phrase there will still be the "penumbra of debatable cases". (The penumbra being the almost-shadow between light and dark).
> If we are to communicate with each other at all, and if, as in the most elementary form of law, we are to express our intentions that a certain type of behavior be regulated by rules, then the general words we use – like “vehicle” in the case I consider – must have some standard instance in which no doubts are felt about its application. There must be a core of settled meaning, but there will be, as well, a penumbra of debatable cases in which words are neither obviously applicable nor obviously ruled out.[1]
I'm most fascinated by it from a UX perspective in public space: how will a user respond to 'penumbral' or edge-case data? Can that be used to refine wayfinding signage? How will a user react or change pathways when encountering information that doesn't fall right in that expected area? (Yes, I'm actually wondering of the implications of actual signage, not just hypothetical.)
We see it often in transit systems. It's where someone might misinterpret a sign or information (in a predictable manner) and latter blame themselves once they learn of the 'intended' information (which will seem obvious in hindsight). Yet, they are not to blame.
[1] Harvard Law Review
Vol. 71, No. 4 (Feb., 1958) - H.L.A. Hart - Positivism and the Separation of Law and Morals [p607] https://www.jstor.org/stable/1338225 (note: it wasn't hard to find a copy via Google)
> If we are to communicate with each other at all, and if, as in the most elementary form of law, we are to express our intentions that a certain type of behavior be regulated by rules, then the general words we use – like “vehicle” in the case I consider – must have some standard instance in which no doubts are felt about its application. There must be a core of settled meaning, but there will be, as well, a penumbra of debatable cases in which words are neither obviously applicable nor obviously ruled out.[1]
I'm most fascinated by it from a UX perspective in public space: how will a user respond to 'penumbral' or edge-case data? Can that be used to refine wayfinding signage? How will a user react or change pathways when encountering information that doesn't fall right in that expected area? (Yes, I'm actually wondering of the implications of actual signage, not just hypothetical.)
We see it often in transit systems. It's where someone might misinterpret a sign or information (in a predictable manner) and latter blame themselves once they learn of the 'intended' information (which will seem obvious in hindsight). Yet, they are not to blame.
[1] Harvard Law Review Vol. 71, No. 4 (Feb., 1958) - H.L.A. Hart - Positivism and the Separation of Law and Morals [p607] https://www.jstor.org/stable/1338225 (note: it wasn't hard to find a copy via Google)