Take “telephones,” for instance. They’ve had a remarkably stable interface since their introduction, but they are now an entirely different technology in almost every other respect. Cellular phones are light years ahead of land lines, but on the other hand, they still have the arrangement 123, 456, 789, *0#. The VoIP revolution is taking hold now precisely because it can change the underlying technology with minimal disruption to the interface.

Note, however, that the telephone interface has in fact changed. Rotary phones became touch tone. Caller ID was added. The dial tone began to signal the presence of voice mail. There is a huge element of conservatism, true– new interface ideas tend to prove acceptable only to the extent that they fail to interfere with the existing interface– but since there are powerful incentives to incorporate new & more powerful technologies into the system, this amounts merely to a requirement of backwards compatibility. You can put in a phone system that does any old crazy thing, and as long as you have to press “star” first, it’s no trouble to anyone who wants to pretend like nothing’s changing.

The next few generations of interface will change this equation even further in the direction of fluidity. The main reason why interfaces with technology have been as conservative as they have, is that they are essentially unintuitive. If you learn by rote a particular arrangement of buttons, you want to stick with it. As interfaces become more intelligent, perceptive and interactive they will become vastly more intuitive, allowing people to interface effectively with a larger amount of computation.

Taking the phone system again as an example, there are already visionaries working on creating the technologies that will finally replace the dialtone. The most likely interface is a voice which says something like, “Hello Bob, You Have Twelve Messages! What Can I Do For You Today?” That may not sound that magnificent– though you must admit it’s preferable to a mildly annoying tone with only historical meaning– but it will improve rapidly as the underlying system becomes more intelligent.

Voice recognition will slowly start to replace dialing. Address books and automated lookups will slowly start to replace memorizing or writing phone numbers. The conservativism will be chipped away at very quickly as things change in ways that make them undeniably easier. The so-called technical aspects of the technology– the medium-tech aspects, the hump of interface complexity– will start to fade away.

And human will begin to join with machine.

Kurzweil claims a ‘Law of accelerating returns’ due to technological innovation, it’s interesting.

I guess I do think that perhaps eventually the technological factors will be so high that they will dominate even the “stronger” linear factors and cause a singularity, but I just don’t see it happening so soon — this is all intutitive of course. But my intuition about this is pretty strong, and since it gets “commonsense” points I weight it more than Kurzweil’s purely intellectual argument. His argument is, at the root, based on looking at the shapes of graphs of the advancement of various technologies, and assuming that other graphs will have that same shape.

(other graphs? besides the computing power graph? yes, most notably, Kurzweil must assume that our ability to write intelligent algorithms that make use of the computing power grows quickly; in the sections of the essay you posted called “The Software of Intelligence”, “Reverse Engineering the Human Brain”, “How to Use Your Brain Scan”, and “Downloading the Human Brain”, he presents examples of projects along these lines that causes his personal intuition to think that the software is within reach in our lifetimes; my intuition disagrees, I think those same projects are much more preliminary and farther from the goal than he seems to — but again, notice that this is just my intuition against his)

More on the “tenor of life” argument; what does that have to do with the rate of technological advancement? Well, to be honest, my intution is simply that “the tenor of life wants to only change slowly” — I am taking that as an axiom, finding that a singularity contradicts it, and then concluding that a singularity is not possible. However, I can manufacture a connection: for technological advance to cause the rate of technological advance to itself increase, I postulate that the technological advance has to cause society to change somewhat to become more efficient. But the speed of that feedback loop is limited by the rate of social and economic paradigmatic change (for example, what if the the internet enables a new economic organization in which “virtual corporations”, social networking, and consulting is the norm, rather than large corporations and conventional long-term employment, and that the new form turns out to be drastically more profitable? What would eventually happen is that society would switch to this new form, and the greater profitability would enable more research, which would raise the rate of tech advancement. But this switch is likely to be slow because of the rate-limiting effect of social and “economic paradigm” change).

I’m not totally ruling out the chance that I’m wrong. I think there’s probably a 10-20% chance that I’m wrong about everything and that there will be a singularity in our lifetimes. It would be neat, if so.

The central thesis of the book is summed up in this Kurzweil essay (which appears as a chapter in the book)… :

http://www.kurzweilai.net/articles/art0134.html?printable=1

RK answers your question in the very first part of the article. Relevant quote (just the starting place for his argument):

“Most long range forecasts of technical feasibility in future time periods dramatically underestimate the power of future technology because they are based on what I call the “intuitive linear” view of technological progress rather than the “historical exponential view.” To express this another way, it is not the case that we will experience a hundred years of progress in the twenty-first century; rather we will witness on the order of twenty thousand years of progress (at today’s rate of progress, that is).”

-K-