The idea that a diverse population needs a diverse environment to succeed seems easy enough to grasp. Certainly, it is easier to comprehend than a one-size-fits-all design philosophy. Why then, in the name of universal design and equality, do architects continue to design uniform one-size-fits-all environments? Answering that is not so simple. Some may suggest that construction methods, costs, and site restrictions make diverse environments economically and physically infeasible. Others may fault the lack of courses architects take in human biology and psychology. This might make it impossible for them to understand the diverse range of people their buildings affect. Even more may fault the ever increasingly abstract design process. This may hinder architects’ ability to identify with real future occupants. All of these conceivably play a role, but the most likely culprit is Plato’s philosophy of essentialism for the same reason biologist Ernst Mayr felt it caused evolution’s insufferably late discovery; essentialism has and continues to fundamentally shape how we see and deal with diversity.
Throughout history variation posed a major philosophical problem for those in search of objective truths both in design and life in general. Plato’s philosophy of essentialism attempted to bring objective truths to what he saw as relative and subjective experiences. According to Plato, a singular essence/definition of any form or idea must exist aspatially and atemporally in order to attain universal applicability among its various representations. For example, no matter whether drawn in the sand or autocad we can easily recognize a triangle when we see one. We can do this because we interpret any smudge or squiggle as an aberration from the true essence of a triangle. Plato called these singular essences Forms, and he applied this logic to everything from triangles to humans. 
For Plato, all human differences represent corrupted and messy shadows projected by the pure Human Form. By defining the singular human archetype/essence, architects could theoretically create environments that would be universally appealing and accessible to all the sullied shadows we represent. It was thought that beauty could be objectively achieved by discovering the proportions of this illusive man. Once discovered, our homes, churches and marketplaces would be equally appealing to all users at all times—in other words the holy grail of architecture. With such a promise, architects, like possessed crusaders, have been trying to capture the human essence ever since the possibility was suggested.
Around the time of Christ, Roman architect Marcus Vitruvius Pollio (Vitruvius) ushered in the most famous proportional essence of man. Vitruvius’s proportional system revolved around the notion of a perfectly built man. He described this well-built man, with his hands and feet extended, as fitting exactly into the most perfect geometrical figures of the circle and square. Vitruvius sincerely believed that a building based on this man’s geometry would achieve universal appeal. For Vitruvius, this harmonious figure was the quintessential definition of the human archetype. It gave architects an objective scale in the face of endless subjective human experiences and preferences. Owing to the Renaissance and Leonardo da Vinci’s 15th century sketch, we have come to know this figure as The Vitruvian Man.
Few enslaved themselves more to Plato’s philosophy than the architects of the Renaissance. Armed with the Greek mathematical rendering of the world, and the Christian belief “that Man as the image of God embodied the harmonies of the Universe,” Renaissance architects saw “the Vitruvian figure inscribed in a square and a circle [as] a symbol of the mathematical sympathy between the microcosm and macrocosm.” This elegantly simple picture of the world transfixed Renaissance architects, and as Rudolf Wittkower stated, “the image haunted their imagination.”
Nearly 500 years after the Renaissance, celebrated architects, namely Le Corbusier, were still producing immutable human archetypes to derive architectural space. For him the Modulor was “a universal instrument, easy to employ, which can be used all over the world to obtain beauty and rationality in proportions of everything produced by man.” He described its proportions as a “range of harmonious measurements to suit the human scale, universally applicable to architecture and to mechanical things.” This quote from Corbusier illustrates how pervasive and clear Plato’s philosophy has remained over the years. It is as if Corbusier has taken the words straight from the mouth of Renaissance architect Leone Battista Alberti. Regardless if present day architects ever read Plato, Vitruvius, or Corbusier, essentialism remains strong in architecture.
The entrenchment of some illusive human archetype in architecture makes it nearly impossible to make any headway against it. For the sake of argument imagine something different than a human. Imagine a dog. Now according to Plato everyone should imagine a wolf. Every domestic dog, from the Japanese Chin to the Great Dane, is a variation on the wolf. Therefore the wolf must be the pure dog Form. The Japanese Chin and the Great Dane are simply corrupted shadows of the wolf projected onto Plato’s cave. According to essentialism we should design all doghouses according the proportions of the wolf. If essentialism is true, then the Japanese Chin and the Great Dane should not only enjoy their new homes equally, but also more than anything designed from the proportions of his or her particular breed. The unwillingness of architects’ to relinquish Plato’s philosophy, and the detriment it has had on universal design’s progress cannot be overstated.
Far from being universal, deriving proportions from a Platonic human archetype isn’t even applicable to a single human being who has or will ever exist. By Plato’s very definition, neither Vitruvius nor Le Corbusier could luckily bump into their proportional men walking down the street. Their archetypes exist outside of this world and outside of time. Vitruvius and Le Corbusier aimed for a one-size-fits-all and ended up with a size that fits no one.
Today, universal design is interpreted slightly different than the days of Le Corbusier. Similar to before, universal design still aims to provide the maximum possible access and appeal for all users to all facilities. Now, however, the focus is on individuals with disabilities. A truly universal design provides enough accommodations for success and removes all obstacles in the environment that make a disability debilitating. Unfortunately, this theoretically engaging idea of universal design gets bogged down in essentialism.
Architects no longer fashion the essence of man as the sum of man’s “best” qualities. It is now inappropriate to suggest that the further one strays from the Vitruvian Man’s flawless proportions the less human a person is. Instead, architects use more abstract, supposedly more “egalitarian,” and less geometric definitions of the human archetype. They do this in one of two ways. They either average our differences into a “typical” range, or derive the “lowest” common denominator between our disabilities.
Reflecting on these fuzzy calculations some distracting images come to mind. “If, for instance, you added up all the women and men on the planet, you would find that, on average, the typical adult human being has one breast and one testicle – and yet how many people fit that description?” Likewise, an image of a Vitruvian Man defined by the lowest common denominator proves more illusive if not impossible to depict. He could not see, hear, move, think, or feel while simultaneously he would be over burdened with too much sight, sound, motion, thoughts, and feelings. Even if we apply this logic to a group of individuals, such as those with sight loss, and not humanity as a whole, we would still end up with ruinous results. Fiona Hind—the Rehabilitation Officer with the Society for the Blind—states, “there are so many different types of sight loss and you can’t create ‘access for all’; universal design is not possible—there are too many contrasts and types with visual impairment and also depth of vision varies so much—you can get two dimensional vision and distance just goes and you have to re-educate yourself about your environment.”Obviously, there exists a disconnect between how some architects conceptualize universal design and the reality of the world.
In reality, the common ground of human equality more likely resembles an undulating landscape than a level playing field. Unfortunately, architects susceptible to essentialism misinterpret our innate equality and, in an effort to provide for every difference in every space at all times, literally design a level playing field. This leveling commonly reduces environmental diversity that in turn threatens accessibility and enriching experiences to both those with and without disabilities. This one-size-fits-all mentality consolidates variation instead of celebrating it. Sandy Speicher—an expert in educational design at IDEO—says, “Too often, equality in education is treated as sameness. The truth is that everyone is starting from a different place and going to a different place.” Speicher advocates for mass customization, both in the system and the classroom. Equality doesn’t mean we require the same environment, but an equal opportunity to address our individual needs.
 Mayr, Ernst. What Evolution Is. Basic Books, New York 2001 p. 74-75.
 Mayr, Ernst. What Evolution Is. Basic Books, New York 2001 p. 74-75.
 Wittkower, Rudolf. Architectural Principles in the Age of Humanism. Norton, New York, 1962.
 Wittkower, Rudolf. Architectural Principles in the Age of Humanism. Norton, New York, 1962, p. 14.
 Wittkower, Rudolf. Architectural Principles in the Age of Humanism. Norton, New York, 1962, p. 14-16.
 Rasmussen, Steen, E. Experiencing Architecture, Cambridge, Mass.: MIT Press, 1959 p. 118.
 What is the essential wolf? Wouldn’t we have regress to the progenitor of the wolf, Canis Lepophagus, and then the progenitor of that and so on and so forth stretching back through evolutionary time?
 Levitt, Steven D., Dubner, Steven J. Superfreakonomics: Global Cooling, Patriotic Prostitutes, and why Suicide Bombers should buy Life Insurance, Hapers Collins, New York, NY 2009
 Imrie, Rob and Peter Hall. Inclusive Design: Designing and Developing Accessible Environments. Spon Press, New York, 2001 p. 17.
 Rydeen, James. “Universal Design.” American School & University. http://asumag.com/mag/university_universal_design/index1.html May 1, 1999.
 Speicher, Sandy. “IDEO’s Ten Tips for Creating a 21st-Century Classroom Experience,” Metropolis.