why do we concern about theories when we deal with practical things

In today's class, someone asked a very interesting, serious and tricky question: "why should we concern about all those theories as HCI designers supposed to work in a very practical field. I felt interesting because I was asking similar question when I read Roger's paper (A reading for today's class, Rogers, Yvonne, (2005) “New Theoretical Approaches for HCI”, ARIST: Annual Review of Information Science and Technology, no 38, 2004. ). My question was: "Are the HCI research community and industry community living in different ages?" Are those super good theories used in all kinds of labs and projects in some universities and colleges or some company ? How many companies are really using ethnographic methods to do their projects with dealing with their clients? I am asking these question not because the paper is not good, in fact, it is excellent paper, and I love it so much! I love the paper because it could trigger my thinking.

I agree that theories provide a common language to let people communicate and discuss the issues in the field. More generally speaking, how could people in the HCI field understand each other by using those same terms or "languages". It could make sense to each of us in the field. Theories provide tools for us to understand the reality situation a design involved in and critique research and designs done by others.

However, seriously, do we do research on theories because of the fear of handling the uncertain? Is it because we are trying to add more certain factors or trying to find an excuse of our responsibility to a design? Does it mean that we are not very confidence about our design ability?

When an "aha" idea comes up and the designer have 100% confidence about her design and its successful future, she could broke all the rules and theories and whatever. Even further, maybe she just creates a totally new theory! Who knows?! WHY? However, the "aha" idea doesn't come up with itself. It comes from the designer's knowledge, judgment, insight and her philosophies. Where these things come from, reflection-on-action? OR theories!

We need theories because we want to make fast designs. What do I mean fast design?
Since we have human society, thousands years ago, we are keeping to design things, all kinds of things, tools, organizations, etc. But thousands years ago, we don't have a lot of theories. For a single tool design, for example, a shovel, it design process maybe last for hundreds of years. Its designers and also users were always looking for better materials and changing forms. This kind of design process mend together with the product using process as well as usability test and redesign process. Therefore, the fast design means that we as both designers and users don't want to wait and go through with the very long design process. We need it now! And I guess my conclusion is that this is the theories for--to condense the design process.