Previously: what is law? - Part 7.
A good place to
start in exploring the Closed World of Knowledge (CWoK) problem in
legal knowledge representation is to consider the case of a spherical
cow in a vacuum...
Say what? The
spherical cow in a vacuum[1] is a well known humorous metaphor for
a
very important fact about the physical world. Namely, any model we
make of something
in the physical world, any representation of it we
make inside a mathematical
formula or a computer program, is
necessarily based on simplifications (a "closed world") to
make the representation tractable.
The statistician
George Box once said that "all models are wrong, but some are
useful." Although this mantra is generally applied in the
context of applied math and physics, this concept is
incredibly
important in the world of law in my opinion. Law can usefully be
thought of as an
attempt at steering the future direction of the
physical world in a particular direction.
It does this by attempting
to pick out key features of the real world (e.g. people, objects,
actions, events) and making statements about how these things ought
to inter-relate (e.g. if event E happens, person P must perform
action A with object O).
Back to cows now.
Given that the law may want to steer the
behavior of the world with
respect to cows, for example, tax them, regulate how they
are
treated, incentivize cow breeding programs etc. etc., how does law
actually
speak about cows? Well, we can start digging through legislative texts to find out but
what we will find is not the raw
material from which to craft a good definition
of a cow for the
purposes of a digital representation of it. Instead, we will find
some or all of the following:
- Statements about cows that do not define cows at all but proceed to make statements about them as if we all know exactly what is a cow and what is not a cow
- Statements that "zoom in" in cow-ness without actually saying "cow" explicitly e.g. "animals kept on farms", "milk producers" etc,
- Statements that punt on the definition of a cow by referencing the definition in some outside authority e.g. an agricultural taxonomy
- Statements that "zoom in" on cow-ness by analogies to other animals eg. "similar in size to horses, bison and camels."
- Statements that define cows to be things other than cows(!) e.g. "For the purposes of this section, a cow is any four legged animal that eats grass."
What you will not
find anywhere in the legislative corpus, is a nice tidy, self
contained
mathematical object denoting a cow, fully encapsulated in
a digital form. Why? Well, the only way we could
possibly do that
would be to make a whole bunch of simplifications on "cow-ness"
and we know
where that ends up. It ends up with spherical objects in
vacuums just as it does
in the world of physics! There is simply no
closed world model of a cow that captures everything
we might want
to capture about cows in laws about cows.
Sure, we could keep
adding to the model of a cow, refining it, getting
it close and
closer to cow-ness. However, we know from the experience of the world
of physics that we reach the point where have to stop, because it is
a bottomless refinement process.
This might sound
overly pessimistic or pedantic and in the case of
cows for
legislative purposes it clearly is, but I am doing it to make a
point. Even everyday concepts in law such as aviation,
interest rates and theft are too complex (in the
mathematical sense of complex) to be defined inside self-contained
models.
Again, fractals
spring to mind. We can keep digging down into the fractal boundary that splits the world into cow and not-cow. Refining our definitions until
the cows come home (sorry, could not resist) and we will never reach
the end of the refinement process. Moreover many of the
real world phenomena law wants to talk about exhibit a phenomenon
known as "sensitivity to initial conditions"[3]. It turns
our that really, really small differences in the state of the world
when an event kicks off, can result is completely different outcomes
for the same event. This is why, in the case of aviation for
example,
mathematical models of the behavior of an aircraft wing can
only get you so far. There
comes a point where the only way to find
out what will happen in the real world is to
try it in the real
world (for example, in a wind tunnel.)
So it is with law. Small
changes in any definitions of people, objects, actions, events, can
lead to very different outcomes. The sensitivity to initial conditions means that it is not possible to fully "steer" outcomes by refining the state of affairs to greater and greater depth. Outcomes are going to be unpredictable, no matter how hard you work on refining your model.
We can come at this
CWoK problem from a number of other perspectives, each of which
shine
extra light on the representation problem. From a linguistics
perspective, in
searching for a definition of "cow" we can
end up in some familiar territory.
For Sausserre[4] for example,
words have meaning as a result of their differences...from
other
words:-) Think of a dictionary that has all the words in the English
language
in it. Each word is explained....in terms of other words! Simply put, language does not appear to be a system of symbols that gets its meaning by mapping it onto the world. It gets is meaning by mapping back onto itself.
From a philosophical
perspective, trying to figure out what a word like "cow"
actually
means has been a field of study for thousands of years. It
is surprising tricky[5], especially
when you add in the extra
dimension of time as Searle does with the concept of Rigid
Designation[6].
Fusing philosophy
and linguisics, Charles Sanders Pierce noted
that nothing exists
independently. I.e. everything we might put a name on only
exits in
relation to the other things we put names on[9]
. We can approach the
same idea from an almost mystical/religious perspective and find
ourselves questioning the very existence of cows:-) Take a look at
this picture
from Zen Master Steve Hagen for example[8] Do you see a
cow? Some people will, some
will not. How can we ever hope to
produce a good enough representation of a cow
unless we all share
the same mental ability to split the world between cow and non-cow?
Echoing Charles
Sanders Pierce, we find the ancient Eastern concept of dependent
origination[10]. Everything that we think exists, only exists in
relation to other
things that we think exist. Not only that, but
because everything is constantly changing with respect to
time, the
relationships between the things – and thus their very definitions
- keep changing too.
This is essentially
where philosopher
John Searle ends up in his book Naming and
Necessity[11]. For Searle, the meaning of nouns, ultimately,
is a
social convention and meaning *changes* as social convention changes.
One final
philosophical reference and then we will move on.
Wittgenstein famously stated that
the meaning of language can only
be found in how it is used - not in dictionaries[12].
As with
Pierce, the meaning can change as the usage changes.
This doesn't sound
very promising does it?
How can law do its job if even the simple
sounding concept of rigorously defining terms is intractable? Law does
it by not getting caught up in formal definitions and formal logic at
all. Instead, the world of law takes the view that it is better to
leave a lot of interpretation to a layer of processing that is
outside the legal corpus itself. Namely, the opinions formed by
lawyers and judges. The way the system works is that two lawyers,
looking at the same corpus of legal materials can arrive at different
conclusions as to what it all means and this is ok. This is not a
bug. It is a feature. Perhaps the feature of law that
differentiates it from classical computing.
The law does not
work by creating perfect unambiguous definitions of things in the
world and states of affairs in the world. It works by sketching these
things out in human language and then letting the magic of human
language do its thing. Namely, allowing different people to interpret
the same material differently. In law, what matters is not that the
legal corpus itself spells everything out in infinite detail. What
matters is that humans (and increasingly, cognitively augmented
humans) can form opinions as to meaning and then defend those
opinions to other humans. This is the concept of legal argumentation
in a nutshell. It is not just inductive reasoning[13], taking a big
corpus of rules and a corpus of facts and “cranking the handle”
to get an answer to a question. It is, in large part, abductive
reasoning[14] in which legislation, regulations, caselaw are analyzed
and used to construct an argument in favour of a particular
interpretation of the corpus.
That is why parties to a legal event
such as a contract or a court case have their own lawyers (at least
in the US/UK common law style of legal system). It is an adversarial
system [15] in which each legal team does its best to interpret the
corpus of law in the way that best serves their team. The job of the
judge then is to decide which legal argument – which interpretation
of the corpus presented by the legal teams – is most persuasive.
This is what I think
of as the Unbounded Opinion Requirement (UoR) of law.
This UoR
aspect, kicks in very, very quickly in the world of law because the
corpus – for reasons we have talked about – doesn't feature the
clear cut definitions and mathematically based rules that computer
people are so fond of. The corpus of law, does not spell out its own
interpretation. It cannot be “structured” in the sense that
computer people tend to think of structure. It has as many possible
interpretations as there are humans – or computers - to read it and
construct defenses for their particular interpretations.
I have been arguing that a “golden” interpretation cannot be in the legal corpus itself, but I think it is actually true that even if it could, it should not be. The reasons for this relate to how the corpus evolves over time and how interpretation itself evolves over time and that this is actually a very good thing.
I have been arguing that a “golden” interpretation cannot be in the legal corpus itself, but I think it is actually true that even if it could, it should not be. The reasons for this relate to how the corpus evolves over time and how interpretation itself evolves over time and that this is actually a very good thing.
A classic example of
a legal statement that drives computer people to distraction is a
statement like “A shall communicate with B in a reasonable amount
of time and make a fair market value offer for X.” What does
“reasonable amount of time” mean? What does “fair market value”
mean?
A statement like
“reasonable amount of time” for A to communicate with B is a good
example of a statement that may be better left undefined so that the
larger context of the event can be taken into account in the event of
any dispute. For example what would a reasonable communications delay
be, say, between Europe and the USA in 1774? In 1984? In 2020? Well,
it depends on communications technology and that keeps changing. By
leaving it undefined in the corpus, the world of law gets to
interpret “reasonable” with respect to the bigger, “open world”
context of the world at the time of the incident.
In situations where
the world of law feels that some ambiguity should be removed, perhaps
as a result of cultural mores, scientific advances etc. it has the
medium of caselaw (if the judiciary is doing the interpretation
refinement), regulations/statutory instruments (if the executive
branch is doing the interpretation refinement) and primary law (if
the legislature/parliament) is doing the interpretation refinement.
One final point, we
have only just scratched the surface on the question of interpreting
meaning from the corpus of law here and indeed, there are very
different schools of thought on this matter within the field of
jurisprudence. A good starting point for those who would like to dig
deeper is textualism[16] and legislative intent[17].
In conclusion and attempting a humorous summary of this long post, the legal reasoning virtual box we imagined in part 1 of this series, is unavoidably
connected to it surroundings in the real world. Not just to detect,
say, the price of barrel of oil at time T, but also for concepts like
“price” and “barrel” and maybe even “oil”!
On the face of it,
the closed world of knowledge (CwoK) and the Unbounded Opinion
Requirement (UoR) might seem like very bad news for the virtual legal
reasoning box
However, I think the
opposite is actually true, for reasons I will explain in the nextpost in this series.
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