Pre-war modernism began with two main schools of thought: De Stijl, a loose-knit group of Dutch designers and artists (including Mondrian and Rietveld), and Bauhaus, a school in Germany occupied by some of the greats of modernism, including Marcel Breuer and Walter Gropius. Together, these two styles of design brought about the early modernist revolution, turning their Dutch and German middle fingers up to the commoner styles of art deco and early modernism such as Wright and Mackintosh.
Everyone knows Bauhaus as the function-before-form lot, but in fact their counterparts at De Stijl had a very different way of doing things. Rietveld, one of the key designers of the group, wanted to focus on 'solving spatial problems' - in other worlds, creating 3D objects that satisfy the eye to the greatest degree, finding perfect formations and perfect shapes in perfect places. For De Stijl, this was all about manipulating lines and geometric shapes (nearly always rectangles) to create common forms, and compositions that were both stable and aesthetically pleasing.
From the book, Rietveld gave this quote: "A practical realisation [of the De Stijl design ethic] was not always feasible. Function for me was a thing by itself which I never overlooked, it is true, but it did not come into play until the construction and spatial exercises in De Stijl had been completed". This, for me, is incredibly interesting - here we have one of the founding fathers of modernism actively ignoring functionalism until the last moment in the design process! What for? To follow a set of rules that De Stijl was based on. I'm by no means criticising this process - I like it, but I feel that function has to come into play a little earlier than it did with, say, the 'Zig-Zag' chair by Rietveld:
If we take the De Stijl standards to simply apply to art and sculpture, then we can let Rietveld off for this one - he was not purposefully creating a functional element, merely satisfy spatial problems with a seat and a backrest. Fair enough; but the more purist designers would argue that all design must include some sort of functionality and ergonomics. Mondrian was more than welcome to go nuts with the right angles in his artwork, but if Rietveld's creating De Stijl furniture and actively including it in interiors (such as the Schröder House in Utrecht), he should have considered function a bit more, in my opinion. It may be just about acceptable for his Red and Blue chair:
This lack of care for functionality may be a result of De Stijl's historical setting - it's still in the earlier 20th Century, so perhaps the form-before-function motif is related to the styles of Victorian and pre-Victorian era design, which had been so dominant in previous centuries. Back then, everything was form before function: people treated furniture as a chance to express grandeur and elegance in their houses, which were similarly styled - that's why function always took a back seat. The theory I'm presenting is that De Stijl, only in the 1920s don't forget, still held this ethic of elaborate form before considering function - function simply didn't figure into the designer's mind until they'd made the aesthetics look as good as possible so they show the owner's wealth and grandiose style.
Later on, Rietveld commented of the Red and Blue chair that it "was made to the end of showing that a thing of beauty, a spatial object, could be made of nothing but straight, machined materials". Putting his continued use of the ever-artistic term 'spatial object' (as if he's sculpting in a 3D plane, much as we do nowadays in CAD and CGI) aside, this shows you that his chair was, perhaps, just a chance to create a Victorian-era chair (complete with elaborations and form-before-function) with the modern straight lines and forms. It's a transitional design state, an important style to be studied, but it's still pre-Bauhaus and we must acknowledge that.
But, otherwise, function must take a bigger role. Elsewhere, Rietveld openly compared himself and his style to Bauhaus: "The Bauhaus approach was very different in that it attempted to develop form on the basis of a clear definition of function." - though Bauhaus designs' starting points were the bare functions; backrest, seats, tabletops, etc - Rietveld's designs were more fluid in their function, and must have depended on what shape the final solution to the 'spatial problem' happened to be. As evidenced by the aforementioned Zig-Zag chair, which has been used primarily as a dining chair but could really be any sort of chair. "Having a strong sense of relativity," Rietveld continues, "I did not think that function as a point of departure was a sound approach. Function was an accidental, casual need that would change with the time and indeed always changes in the course of time." This is a drastically different way of thinking from the down-to-Earth Germans at Bauhaus, a little further east. In fact, most of the Bauhaus designers would have scorned Rietveld for such a non-functionalist view, it's crazy to think he sits alongside them in 'Bauhaus designers' websites - if this post proves anything, it's that Rietveld and De Stijl and clearly not part of Bauhaus, merely a precursor to the Germans.
Suffice to say, I think we should classify De Stijl as pre-modernism, or early transitional modernism. 'Transitional' is an important word to use in relation to those Dutch designers and artists, because not only did they blend traditional and modernist ways of designing, but they blended art and design, creating boxy sculptures we can live in or sit on. Not only were chairs to be adorned with artistic details, but they were now stripped of details and treated as 'spatial objects', sculptures solving 'spatial problems' and finding perfect forms, then throwing in function as a 'casual need'. Though I don't necessarily see this process as creating the best design, I still love the Red and Blue chair and Rietveld's designs are certainly not to be forgotten. Not all modernism was functionalist.