who’s ever developed an application from scratch knows that it’s difficult to fully
understand the objective of the user or subject matter expert, when they
describe the problem that the code is supposed to solve. It’s not a mystery
that the requirements gathering process is a challenge. However, why it’s so
difficult to get good requirements and what you can do about it are a mystery.

review the objective of gathering requirements (or elicitation, if you prefer
an agile moniker), what makes it difficult, and what you can do about it. To do
that we need to examine: what tacit knowledge is, what explicit knowledge is,
how to convert one to the other, and why you should care.

Tacit knowledge

knowledge is knowledge based on experience and observation. There wasn’t some
law or procedure handed down from on high. It’s just the way that things are
done. It’s something that is immensely powerful because it’s relevant. It can
be directly applied to the activities that will need to be done in the future.

example of tacit knowledge comes from a buddy of mine who does handyman work
for a living. He and I like to work on projects together because we have great
conversations. Recently we were building drum raisers for the church in my
garage. He was constantly sprinkling all sorts of bits of knowledge. We built
the frame before attaching it to the decking rather than attaching the frame to
the deck one board at a time. Why? The answer was that getting it all to line
up works better that way. How does he know? He’s done this general sort of
thing (building cabinets and platforms) enough that he just knows.

knew all sorts of things, like making sure that the crown of the board, the
slight curvature that’s normal for all wood, are all going up. Why? Because
when load is applied it will tend to bend it down to a flat or neutral

example was something I learned in college several years ago. It was about loop
structuring. An instructor of mine suggested a loop structure that did an
initial read of a record before the top of a loop. The structure I was using at
the time performed the read just after the top of the loop. The result was a
loop that had a big if block inside of it. When she suggested the new structure
of putting the read statement before the loop, I asked why? Her answer was
“It just works out better that way.” She knew from experience that
the structure worked out better if you performed the read before the start of
the loop (and at the end of the loop.)

knowledge is the basis of apprenticeship programs. You learn how to do
something through gaining experience with someone else who already has more
experience than you. This approach illuminates small subtle ways of making a
better product or working more quickly which would be hard to capture into a
formal textbook on the subject.

folks just know how to make things work from experience. You may be hard
pressed to get them to explain their knowledge to someone else or even to write
it down but the knowledge of how things should be done is there and it’s built
upon experience.

Explicit knowledge

knowledge is, on the other hand, knowledge that can be quantified. It can be
written down and clearly communicated to another human being. It’s tangible. There’s
no need to gain experience. It’s something that has been converted to a rule.

instance, one may observe that apples fall from trees and know how to shake the
tree to get them – tacit knowledge – and they may also know that gravity causes
all objects of mass to come together. The observations in the first case, tacit
knowledge, were converted to a law in the second case, explicit knowledge.

knowledge is the type of knowledge conveyed through articles, books, seminars,
and video presentations. There is no need to have direct experience with
something to have explicit knowledge about it. This is one of the criticisms of
college students who are just graduating. They have a lot of “book
knowledge” (explicit knowledge) but lack real world experience (tacit
knowledge). Clearly then we know that no matter how great the explicit
knowledge it can not always replace tacit knowledge.

On the
other hand since the Gutenberg printing press explicit knowledge is transferred
at a much more rapid rate. You are reading these words and learning more about
the different kinds of knowledge because I’ve been able to convert tacit
knowledge of how things work into a set of rules that you can use.

Understanding the conversion process

Kuhn, a philosopher of science, argues that science comes in cycles of
“regular science”, “crises”, and “revolutionary
paradigm shifts”. This model demonstrates the relationship between
explicit knowledge and tacit knowledge as it relates to the development of new
science. We start with tacit knowledge which is the core of the scientific

first step in the scientific method is to observe – in other words to develop
experience. It is from there that we hypothesize how the thing we’re observing
works. The next step is to test the hypothesis and finally if incorrect we test

output of the scientific method is a nugget of explicit knowledge – a tested
hypothesis or theory about how the world works. This explicit knowledge can be
easily and quickly communicated between humans without the need for extensive

however, realized that this is not the end. Eventually flaws, gaps, or errors
in the hypothesis will arise. This will create a crisis where the explicit
knowledge comes into question. This tacit knowledge, refined by the focus
brought by the explicit knowledge, begins to challenge the explicit knowledge
under which the world seems to operate.

the pressure brought to bear by new tacit knowledge creates a revolutionary
paradigm shift that creates a new explicit knowledge that becomes the basis for
all new tacit knowledge to become known.

process happens over and over again in small ways and in big ways. Simple
things like the discovery of quantum physics radically changed our view
Newtonian physics. There was a crisis because we were trying to apply a
hypothesis – a thoroughly tested one – to an area where the hypothesis didn’t
hold true.

net effect is that both kinds of knowledge are necessary; however, it is
explicit knowledge that is easier to convey.

Converting knowledge

tacit knowledge into explicit knowledge is a real trick – a real leap of faith.
It takes someone with vision to see the line that fits between all of the dots
of observations and experience. It’s a bit of magic not unlike the process of
converting requirements into design or a caterpillar converting to a butterfly.

task of making the conversion isn’t just as simple as making the connections. There
are some issues with the way that we process information and the makeup of our
brains which hinders our ability to make these conversions.

In Blink, Malcolm Gladwell raises some interesting points. In Chapter 4
Paul Van Riper’s
Big Victory
“, Gladwell points to the work
from Jonathan Schooler who researches verbal
overshadowing. The point of his study is to understand why we’re able to
recognize faces quickly until we are asked to describe them. His work explores
how the verbal part of your brain interacts with the mental parts of the brain
such that it’s both difficult to describe pictures as words and how the process
of even attempting this seems to reduce the fidelity of the original image.

Chapter 5 “Kenna’s Dilemma“, Gladwell
revisits the topic by sharing how we adjust our preferences to
plausible-sounding reasons. Jonathan Schooler did and
experiment with Timothy Wilson. In this experiment experts and college students
were asked to subjectively describe which strawberry jam they liked best. The
experts and the college students by-and-large agreed. That is unless the
students were asked to quantify their rankings at which point all correlation
between the experts and the previous students disappeared. This illustrates the
problem with converting knowledge from tacit to explicit. When asked to create
an explicit perspective on the jam they created plausible sounding reasons for
liking one jam over another and then adjusted their perceptions to match the
plausible-sounding reasons. In other words, they changed the way they
remembered the jam to match what they described.

Gladwell continues and points out that experts have somehow overcome
the limitations that seem to plague the less expert in part by creating a more
precise understanding of how to rate foods. The structures that the students
came up with didn’t have the fidelity necessary to accurately portray their

In the
software development world, a world of creativity, it’s sometimes difficult to
get to the true best practices, the rules, the guidelines and techniques which
lead to good software development. Undoubtedly there are issues such as
different languages which subtly shift the best practice and make it more
difficult to identify. However, at its core the issues remain the same and we
must lean to convert our knowledge in requirements specification into an actual

Getting the conversion done

So if
expert food testers can quantify the differences in jams with no real
difference in the outcome, so too can we convert tacit knowledge of how
software can and should be developed into the explicit knowledge that we need
to be able to communicate with the entire development team – or the entire

food testers had very precise scales and very precise attributes they were
rating. So too can we clearly define the characteristic behaviors that must be
present for good software development. We can also clearly define the metrics
where by those behaviors are measured.

of just saying that you “keep in touch” with developers it’s possible
to define an “informal communications” attribute which can be
measured. Once the attribute is defined it’s possible to define points on the
continuum of that attribute. From this a workable understanding can be created.
For instance, a 0 on a 0 to 100 scale might mean that you never talk to the
other team member.” A 100 on the scale might be that you share office
space with them.

actual value and the specific attributes that you select for your organization
are not necessarily important, but the ability to quantify what you have is
important. You may learn, for instance, that in order for your team to work
well together they need to have a certain level of informal, non-structured

explicit knowledge becomes a periodic set of events that support the underlying
observations. The explicit knowledge is that every quarter there should be four
hours of time set aside so that team members can communicate without structure.
This clearly misses the underlying knowledge of how teamwork is developed and
the level of team work that is required for the group to operate effectively –
however, this tacit knowledge isn’t necessary for most cases. All people need
to know is what to do – to create informal communications – not necessarily why
it works.

Breaking the rules

One of
the interesting observations that we take from Kuhn is that sometimes it’s
necessary to break the rules – to go outside of the explicit knowledge. No
where is that more true than running sound for a live event. There are a set of
rules – or guidelines – for how to setup things so that they sound good. These
rules are extremely effective for those who don’t have a great deal of
experience. They simplify the process and make it manageable.

an experienced sound person often breaks (or severely bends) the rules to suit
their needs. While you may “never” want to use a large diaphragm
condenser microphone on a noisy stage, this may be precisely what an
experienced sound engineer does. He does this because he has the tacit
knowledge that contains a more precise understanding of how to make this work
than the explicit knowledge in the rule.

So go
make some explicit knowledge – and then go break the rules.