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  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
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  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
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
 Searle, J. (1969). Speech Acts. Cambridge,
UK: Cambridge University
 Austin, J.L. (1962). How to Do Things with Words. Oxford: Clarendon Pres.