Designers love diagrams. We tend to be visual thinkers. Where verbal thinkers feel they understand things when they find the right words to express a thought, designers feel they understand when they find the right shape. And so it is not surprising that designers understand their own work in diagrams.

If you ask a designer what they do, there’s a strong chance they’ll draw a Venn diagram. There is an equally strong chance one of the three overlapping circles will be labeled “Desirable”.

Perhaps the most popular one is the Desirability-Viability-Feasibility triad. My first exposure to it was the late 90s, but expressed in different language. A User Experience Architect used it to explain to me that our role was responsible for finding the overlap between 1) “User” (what users want and need), 2) “Technology” (what is technologically possible), 3) “Business” (what serves business goals), and 3) . At least according to one source, it was IDEO who developed and popularized the now ubiquitous Desirability-Viability-Feasibility model. What is Desirable, Viable and Feasible satisfies the needs of people, is good for the business, and can be developed and delivered easily enough that it is worthwhile to do.

Another version, which I believe predates the other by almost a decade is the Usefulness-Usability-Desirability triad. When designers focus on the benefits they provide to people — and this is our primary focus — we often speak of these benefits in terms of good experience. This triad clarifies what is meant by “good experience”.

A good experience has three qualities: It is 1) “Usefulness” (the design satisfies functional needs), 2) “Usability” (the design minimizes functional obstacles), and 3) “Desirability” (the design is valuable beyond its function).

Years ago, I became curious where this triad originated. It turns out it was conceived in 1992 by Liz Sanders, who is now known primarily for her work in participatory design. To the degree a design affords usefulness, usability and desirability, it will be valued by people and adopted.

So which of these two Venn diagrams is preferable? They seem to do similar things with a similar shape and with one overlapping word. Do we just choose the one we like better? Do we just choose the one that we think will resonate more with our audience?

I propose that these two triads complement each other. This becomes easier to see if we avoid using the word “Desirability” in two different ways. In the Desirability-Viability-Feasibility triad, Desirability is about people’s response to what is being designed. It asks if the design will actually be adopted. Let’s call it “Adoptability”.

And adoptability is the goal of good experience. Looking at the Usefulness-Usability-Desirability triad, they define what is adoptable. So the Usefulness-Usability-Desirability triad fits inside the Adoptability region of our new Adoptability-Viability-Feasibility triad.

Not one to stop while I’m ahead, I’ve decided to add yet more elements. I’ve been warned by trusted colleagues that I’m pushing it too far. I’m going to try anyway.

Years ago I heard someone, and I suspect it was Jared Spool, talk about design having two modes. 1) “Design the right thing.” 2) “Design the thing right.”

I see the first triad Adoptability-Feasibility-Viability as representing “Design the right thing.”

I see the second triad Usefulness-Usability-Desirability as representing “Design the thing right.”

So far so good?

Ok. But here’s where I got in trouble with my colleagues. While I was digging around the internet to confirm that Jared Spool was in fact the inventor of “Design the right thing.” / “Design the thing right.” I came upon an article that mapped these two statements to the famous Double Diamond of design thinking. And I got all excited about mapping the two triads to the diamonds to produce a  Grand Unified “What Designers Do” Diagram.

I received two objections. The first objection points out that we are not only thinking about adoptability-feasibility-viability while defining our problem. We also think about usefulness, usability and desirability. And once we think about designing a thing right in the second diamond, we don’t stop worrying about feasibility and viability.

Honestly, none of this bothers me. In design, when we describe what we do, we exaggerate and sharpen definitions and separate things that are blurrier and messier and more intermingled in real practice. We’re just trying to help people conceptualize, and this makes it easier. It is roughly true. Good enough.

The second objection, however, might be fatal. But if it fails, it seems to be an interesting failure, so I’ll expose the idea with the objections and see what happens. If I can’t rescue it, maybe somebody else can.

The objection is this: While it is true that the first diamond is where we determine what the right thing is to design — and while it is also true that the right thing to design is adoptable, feasible,  and viable — it is not necessarily true that the first diamond helps us determine what the right thing to design is by defining what is adoptable, feasible,  and viable. Adoptability-Feasibility-Viability is more commonly used as a framework for evaluating concepts, and that is something that belongs in the second diamond.

But then, I’m thinking… Maybe designers should be thinking more about how we can bring feasibility and viability into that first diamond.

Perhaps we are overemphasizing Adoptability when framing our opportunities and design problems.

I don’t know the answer. But I do know from years of design practice that sometimes clearly framing a question is the key to better answers. So I’ll leave it open.

Thoughts?