Classen’s law


Sean Park’s ‘The power of power laws‘ reminded me once again of one of my favourites – Theo A C M Classen’s “logarithmic law of usefulness”. I finally got around to doing a WikiPedia entry for it here, which I hope is notable enough to survive the WikiPedia deletionists (about which I’m entirely in agreement with Tim Bray).

It’s because of Classen’s law that I’ve declared myself as a singularity non believer (even though I enjoy reading singularity inspired SF). I think to have a real singularity it would take something that would drive an exponential increase in usefulness, and if Classen’s right that would need something to drive technology at a double exponential rate. Given how hard it has turned out to be to keep Moore’s law a reality that seems unlikely, though when Moore’s law finally has a hard collision with the laws of physics who knows what might emerge to take the place of reducing the feature size of 2D semiconductors?

4 Responses to “Classen’s law”

  1. 1 Chris Swan

    In case the deletionist do get to the WikiPedia entry, an older article can be found at

  2. Thanks Chris, had not previously heard Classen’s Law (under any nomenclature). However I’m not sure I agree that a Mondeo is not significantly more useful than a Model T to get from A to B. (“How” matters imo.)

    Also, having spent some time and energy delving into the singularity literature a couple years back, I feel sheepish saying my strong opinion is a cautious not sure/agnostic… however one lesson that I did take away that very clearly helped me understand the world around me (in particular the corporate world) and in particular the inability of 99% of people to think about possible future outcomes in a non-linear fashion.

    The number of times over the past 20 years I was told that my idea or scenario was preposterous frankly was starting to get me down. Not that I was always right – of course I was often wrong – but I feel confident that what I suggested was never preposterous (and indeed most of these same people would admit as much when the future arrived – ie that even where I was wrong, the prediction had turned out to be plausible.) So when Kurzweil articulated the linear vs exponential thinking thesis I was relieved as it seemed to accurately describe the world and reaffirmed my confidence in my own lucidity.

    I can’t remember to whom it should be attributed, but the old expression – much less happens in the next year than we expect, much more in the next ten – is a fundamental truth that has its roots in the power law…

  3. 3 Chris Swan

    Thanks for the insight Sean, and I agree that how does matter (as that’s the only rational explanation for why I find myself with two cars, a motorcycle and a scooter).

    I think the key problem when using power laws in this way is determining when a mathematical trend to infinity will actually hit something imovable in the real world. Semiconductor design is already struggling with quantum effects at feature sizes you can buy today (45nm). The big guys have roadmaps out to 16nm, but that doesn’t take us very much further, and may really be the end of the road. For the ‘computer more powerful than the human brain’ we’re going to have to jump S curves (which is where I think the real excitment happens – just look at what’s going on with SSD vs HDD right now).

    It was Bill Gates that said “We always overestimate the change that will occur in the next two years and underestimate the change that will occur in the next ten. Don’t let yourself be lulled into inaction.” From his book, “The Road Ahead,” published in 1996. (

  4. 4 Arun

    Hi Chris,
    I had read an article about Classen’s law ages ago (1999?) and remember being hugely impressed. At a time when I was a student of microelectronics overwhelmed by the technology of shrinking geometries, it made complete sense to me.
    Thanks for keeping this alive.

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