Form Follows Function. It is a great soundbite, but until the form is established, there is no way to know whether or not it performs its intended function, except in theory. And, as is well known, theories are human constructs, prone to error. So, even with our mathematics and physics we have to try things out first.
The intention of FFF, in relation to its original architectural context, was to simply emphasise the practical, at the expense of the ornamental. However that has little to do with the way it is often interpreted by designers of all sorts of products today, namely that the function (what the designer thinks is required) should determine the form (what the designer thinks is the best way to serve that function).
Immediately the problem becomes apparent: for this method to work, the designer has to actually know all the requirements for the item being designed, and then he has to actually know how to achieve it. Who can have absolute knowledge without experience first? No one.
So, the designer makes his item, it does a reasonable job, he redesigns it, it gets better, he refines it further, it gets better still. Then usually another designer comes along with a new concept that the first designer hadn't even thought of, and makes it even better.
So the way the item functions governs its new form. And the way that form functions governs further new forms. It is an evolutionary process, not a prescriptive one. Louis Sullivan should really have reversed the statement, and said instead: "Function ever follows form", or perhaps "Function follows form follows function follows form follows..."
