Conceptual integrity is the quality of a system where all the concepts and their relationships with each other are applied in a consistent way throughout the system.
Fred Brooks in his classic The Mythical Man-Month talks about conceptual integrity -
"I will contend that conceptual integrity is the most important consideration in system design. It is better to have a system omit certain anomalous features and improvements, but to reflect one set of design ideas, than to have one that contains many good but independent and uncoordinated ideas."
"Conceptual integrity in turn dictates that the design must proceed from one mind, or from a very small number of agreeing resonant minds."
Conceptual Integrity does not emerge from democracy; see A Camel is a Horse designed by a committee. The result of a democratic approach is a compromise that does not meet the needs of any single person or the customer.
Conceptual integrity is extremely important in product designs. See an API that is very easy to use, even without documentation? See a website that achieves the same task in the same way across various web pages? See the employees in an organization articulate the product concepts in a consistent manner? These are all results of conceptual integrity that has been successfully achieved.
So, how does one achieve it. Fred brooks offers an elegant and obvious solution:
"... the most important action is the commissioning of some one mind to be the product's architect, who is responsible for the conceptual integrity of all aspects of the product perceivable by the user."
"For quite large products, one mind cannot do all of the architecture, even after all implementation concerns have been split off. So it is necessary for the system master architect to partition the system into subsystems. The subsystem boundaries must be at those places where interfaces between the subsystems are minimal and easiest to define rigorously. Then each piece will have its own architect, who must report to the system master architect with respect to the architecture."
Of course, managers need to recognize the importance of conceptual integrity, and organize to ensure its realization ...
I attended a talk recently about an application that consumers can use to make better shopping decisions across various ecommerce sites. The architect for the application began his presentation by talking about the infrastructure (or middleware) that was used to build the application, which included the 'cloud', 'NoSQL'. The presentation was attended by several engineers in the valley, and was well received, until a member of the audience asked - how was the choice of infrastructure influenced by the customer need for better and faster shopping decisions? As it happened, the benefit was really to the company in minimizing its operating costs, and the application could have better served the customer with a different style.
An individual makes the case for a product (horse). It is introduced to few people who realize its potential. The stakeholders engage and define a process and committee (one representative from each stakeholder), with no one in lead. The committee develops a camel (the individual has probably moved on).
Per Wikipedia "Design by committee is a term referring to a style of design and its resultant output when a group of entities comes together to produce something (often the design of technological systems or standards), particularly in the presence of poor leadership. The defining characteristics of "design by committee" are needless complexity, internal inconsistency, logical flaws, banality, and the lack of a unifying vision."
An approach that produces something closer to a horse
Let the product germinate and bloom with the individual
Let the shoot emerge and support the individual with a small set of people who collaborate
Incrementally let the product grow the realties of the world and support it with more people
Keep the individual at the core maintaining the vision