Objectively Correct Requirements

by Nick de Voil 23. May 2012 15:23

I've been reading a piece by Tal Bloom on the excellent UXmatters site about triangulation of requirements to ensure that "objectively true" requirements are defined. It's a nice article but I do object to some of the ideas implicit in the terminology.

Without people necessarily realising it, the chimera of "objectively true" or “correct” requirements has bedevilled development projects for decades and there's a widespread but largely unspoken belief in the validity of the concept.  I don't believe it's helpful. A requirement is not a neutral fact and the idea of objective truth is simply not applicable when speaking of requirements.

A requirement is in reality a complex speech act [1] within a complex context. I would formalise this as follows.

Part 1 (Context): Person or group of people A asks and/or pays another person or group B to design, construct and/or deliver a product or service C, which will be used for functions D1..Dn by a person or group E in context F.*

Part 2: (Speech act): A says to B, “you will have fulfilled our contract if and when the situation G, i.e. the use of C by E in F, is characterized by attributes H1..Hn when perceived by person or group I.” **

Now, if we're talking about the engineering of a physical deliverable such as a building, a bridge or an aircraft, then D1..Dn and F are stable and don't vary depending on the identity of E, and we can define H1..Hn in ways that are relatively uncontroversial and don't vary depending on the identity of I. In this context, D1..Dn support simple and universal physical human activities such as locomotion and shelter. F is bounded by well-known laws of physics, physiology, meteorology, geology, mechanics and so on.

However, if the system under consideration is a human activity system, or an information system that is to support a human activity system, then D1..Dn and F are subject to unpredictable change and H1..Hn are hard to define in a reliable and uncontroversial way. In this context, D1..Dn support activities, tasks and objectives which can often only be defined in terms whose meaning is individually or socially constructed. The same applies to F.

So Part 1 presents some difficulties of its own where "objective truth" is concerned, although the requirements engineering and business analysis fraternities have gone a long way towards developing solutions. But the real problem is Part 2. A speech act of this type isn't amenable to evaluation in terms of truth. It's a performative [2] utterance rather than a constative one - in other words, it doesn't purport to be a statement of fact. Rather, it constitutes the taking of a position by an actor. To complicate matters further, a truly holistic view would recognise that in practice there are often multiple contracts negotiated between different pairs of stakeholders.

It's curious that the way we often talk about requirements seems to owe a lot to the ancient Greek philosophers. To speak of "impurities" in requirements suggests that a requirement is a substance like iron or gold with an inherent essence, as Aristotle might have said. In view of the complex web of meanings implied by the above, this is clearly wrong. Likewise, language such as “vision”, “lift individuals beyond their own personal, limited perspective into a place of true collaboration” and “objectively true project requirements” implies a belief in a Platonic ideal which the deliverable should approximate or tend towards. I think we need to look at things a different way and recognise that no such ideal ever exists except for very "hard" systems engineering problems.

All that said, I agree with the central point of the article, which I would put this way: the most reliable way of reaching an outcome which is satisfactory to all parties is to ensure that A1..n, B1..n, E1..n, I1..n all have the opportunity to reach a shared understanding of what constitutes G and H1..n. I would add that, for a complex product, this is a cyclical process informed by experience and dialogue, like all human meaning-making (hence the value of prototyping and perpetual beta). It might be tempting to suggest that something must be objectively true if a large number of people agree on it, but that consensus will often only be a fleeting one.

 

*Note on Part 1: This definition can be broken down further as follows:

 Part 1.1 (Contracting context) ): Person or group of people A asks and/or pays another person or group B to design, construct and/or deliver a product or service C1

Part 1.2 (Usage context): Product or service C2 is used for functions D1..Dn by a person or group E in context F.

 

**Note on the whole definition: This describes the situation where the supplier is contracted to provide a product to a customer. A different but increasingly common situation involves a supplier designing a product which it hopes to sell to multiple customers, as follows:

Part 1 (Context): Person or group B decides to design and construct a product or service C, which will be used for functions D1..Dn by a person or group E in context F, in the hope that person or group A will buy it.

Part 2: (Speech act): B say to themselves, "A would wish the situation G, i.e. the use of C by E in F, to be characterized by attributes H1..Hn when perceived by person or group I."

User-centred design adds another perspective to this definition of Part 2:

I says to B, "A would wish the situation G, i.e. the use of C by E in F, to be characterized by attributes H1..Hn when perceived by person or group I".

 

References

[1] Searle, J. (1969). Speech Acts. Cambridge, UK: Cambridge University Press.

[2] Austin, J.L.  (1962). How to Do Things with Words. Oxford: Clarendon Pres.

Comments

Add comment


 

  Country flag

biuquote
  • Comment
  • Preview
Loading