Book Review: The Age of EM


The George Mason economics department is the only academic department in the country whose books I almost always read.

This is quite surprising given how many academic departments there are, as well as the fact that GMU is not a selective university.

But it is true.

I hope they keep churning out good books.

They’ve also been very hospitable. Bryan Caplan and Robin Hanson took me to get good Indian food a few years ago.


Robin’s new book is The Age of EM: Work, Love, and Life When Robot Rule the World.

It is worth reading for (at least) the following reasons:

It is a survey of  us: To extrapolate what the em world might be like, Robin summarize the key findings of numerous academic fields. This vehicle makes the book a fascinating survey of what we know about humans – think David Brook’s The Social Animal, but through a more removed lens, and with a deeper blend of hard and soft sciences.

It might not be too far away: One never knows with such things, but it’s probably worth spending some time on what the world might look like over the next few centuries.

It is a thoughtful framework: The underlying framework of the book is a model based on the idea that:

(1) Once one understand the physical conditions of a society (population size, physical hardware, energy sources, etc.); and

(2) catalogue what research on humans tells us about how varying these conditions affects societies; then

(3) one can make reasonable predictions about what any society might be like so long as its members are somewhat similar to humans and you can approximate the society’s baseline physical conditions.

Like any model, it’s biggest risk is probably garbage in -> garbage out.

But, at the very least, Robin is transparent in what’s going in, so readers can judge for themselves.


Here’s a brief summary of the book:

1. The next singularity (hunter gatherer -> farmer -> industrial age) may occur when we are able to upload human brains onto computer hardware. Robin calls these ems (emulations).

2. This will likely occur before AI becomes conscious through non-copying methods (think Ray Kurzweil type predictions).

3. While ems will surely be very strange to us, given that the are born from copies of human minds, they should not be so strange that our knowledge of human societies will be completely inapplicable to em societies.

4. As such, applying key research insights from humans (psychology, economics, sociology, etc.) can help us predict what this next world might be like. Robin goes on to do this in each chapter by applying key principles of academic areas to the likely conditions of the em era. There is too much here to summarize – read the book if you want more detail.

5. Em brains will move very fast (due to better hardware), so while the em era might only last a few human years or decades (until the AI singularity occurs), for the fastest ems, the subjective era will last much longer that, perhaps thousands of years.

6. Understanding the em era may help us make better policy decision as we transition into the em era, as well as better predict what will happen after the em era.


Here are some of the most interesting ideas in the book:

1. Mind speeds: I had not previously spent much time thinking about how our brain’s hardware affects the speed at which we think. As it happens, our minds are spectacularly slow compared to what’s feasible with other materials! Better hardware, as well inequalities of hardware across individuals, will likely drive many parts of em society.

2. Death in the time of copies: An individual’s relationship to death is much different when you can make and store copies of yourself. Given how much of our current lives and societies are wrapped in who dies / how they die / when we die – a world where death is less central has major implications for identity, values, and relationships.

3. Security concerns are paramount: Theft (making copies of you without your permission) thus becomes almost more of an issue than death. As such, laws and cultural taboos will shift with security becoming more central to em value systems.

4. Less democratic: In a short period of a time, a well run non-democratic regime can outperform your average democracy. However, in the modern human world, these regimes often implode on themselves before they can dominate the rest of the world. But in the em world, things will move so fast (economic doubling rates are incredibly fast, every month or two!), that the rewards to short bursts of effective non-democratic regimes may be very high.

5. Religion: I tend not to think of robots as religious, but Robin makes the case that the utility of religion (nicer hard-working people) and the values of the em world (more farmer like) should lead to increased religiosity.

6. Increased utility: The sheer number of ems, coupled with their high mind speeds – as well as the likelihood that there lives will be ok in terms of meaning and happiness – suggests that the transition to an em world will be a positive utility move.


I am not an expert, so these may be foolish questions, but here were my questions and critiques:

1.Predictive power: While it seems clear that humans can make decent forecasts within their singularity (Robing gives some examples), it’s another to think that humans can make decent forecasts across singularities. Could a hunter and gatherer really have predicted the  industrial world? A farmer?

2. What is it really like? I wish that Robin had introduced us to an  em (or em clan) and then followed them through the book. A real life example would have helped me get a better feel for the em world. I would loved to have been told a story, for example, of an em clan trial  where they punished one of their own copies for stealing the identity of a rival clan, which resulted in a nuclear war strike on one of the clan’s main cities. Or something like that. I could have used more em perspective to get a feel for their world.

3. Avoiding Malthusian conditions: Robin seems convinced that the low cost of reproduction will lead to Malthusian conditions. And he is skeptical that a world government (if it even existed) would be able to stop replications. Perhaps. But in our own time the rapid decline in birthrates, which was an emergent phenomenon not mandated by government, was also unexpected. Is is not possible this could happen in the em world as well? Perhaps via culture? Perhaps it would become taboo to replicate yourself, akin to teenage pregnancy? Robin views our maladaptive (from a reproductive standpoint) society as an odd blip – but perhaps this will be a common condition of all advanced lifeforms?

4. Evolution: I wish there had been a chapter explicitly organized around evolution. Natural selection has been the dominant algorithm of humanity, exactly how would this work in the em world? Robin covers many evolutionary themes but an explicit chapter would have helped me think through and re-read on the issue.


As a non-expert, this book was very hard to review.

I hope I did it some justice.

11 thoughts on “Book Review: The Age of EM

  1. robinhanson

    Nice review. FYI, it is “Em”, not “EM”; it is not short for a two world phrase, it is just the first two letters of the word “Emulation”.

  2. robinhanson

    On #2, hopefully some others will write stories in this setting. On #3, if a taboo raised wages by a big factor, then most anyone could make enormous wealth via stealthily violating the taboo.

    1. nkingsl

      That would be great on #2. On #3, I hear you – just trying to pressure test notion that malthusian conditions can only be avoided through severe government control. Will continue to mull over. I clearly don’t have a great story to tell right now on this.

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