There are smart intellectuals out there think economics is all hogwash, and who resent economists continuing on while their concerns have not been adequately addressed. Similarly, people in philosophy of religion and philosophy of mind resent cosmologists and brain scientists continuing on as if one could just model cosmology without a god, or reduce the mind to physical interactions of brain cells. But in my mind such debates have become so stuck that there is little point in waiting until they are resolved; some of us should just get on with assuming particular positions, especially positions that seem so very reasonable, even obvious, and seeing where they lead.

Similarly, I have heard people debate the feasibility of ems for many decades, and such debates have similarly become stuck, making little progress. Instead of getting mired in that debate, I thought it better to explore the consequences of what seems to me the very reasonable positions that ems will eventually be possible. Alas, that mud pit has strong suction. For example, Tyler Cowen:

Do I think Robin Hanson’s “Age of Em” actually will happen? … my answer is…no! .. Don’t get me wrong, I still think it is a stimulating and wonderful book.  And if you don’t believe me, here is The Wall Street Journal:

Mr. Hanson’s book is comprehensive and not put-downable.

But it is best not read as a predictive text, much as Robin might disagree with that assessment.  Why not?  I have three main reasons, all of which are a sort of punting, nonetheless on topics outside one’s areas of expertise deference is very often the correct response.  Here goes:

1. I know a few people who have expertise in neuroscience, and they have never mentioned to me that things might turn out this way (brain scans uploaded into computers to create actual beings and furthermore as the dominant form of civilization).  Maybe they’re just holding back, but I don’t think so.  The neuroscience profession as a whole seems to be unconvinced and for the most part not even pondering this scenario. ..

3. Robin seems to think the age of Em could come about reasonably soon. …  Yet I don’t see any sign of such a radical transformation in market prices. .. There are for instance a variety of 100-year bonds, but Em scenarios do not seem to be a factor in their pricing.

But the author of that Wall Street Journal review, Daniel J. Levitin, is a neuroscientist! You’d think that if his colleagues thought the very idea of ems iffy, he might have mentioned caveats in his review. But no, he worries only about timing:

The only weak point I find in the argument is that it seems to me that if we were as close to emulating human brains as we would need to be for Mr. Hanson’s predictions to come true, you’d think that by now we’d already have emulated ant brains, or Venus fly traps or even tree bark.

Because readers kept asking, in the book I give a concrete estimate of “within roughly a century or so.” But the book really doesn’t depend much on that estimate. What it mainly depends on is ems initiating the next huge disruption on the scale of the farming or industrial revolutions. Also, if the future is important enough to have a hundred books exploring scenarios, it can be worth having books on scenarios with only a 1% chance of happening, and taking those books seriously as real possibilities.

Tyler has spent too much time around media pundits if he thinks he should be hearing a buzz about anything big that might happen in the next few centuries! Should he have expected to hear about cell phones in 1960, or smart phones in 1980, from a typical phone expert then, even without asking directly about such things? Both of these were reasonable foreseen many decades in advance, yet you’d find it hard to see signs of them several decades before they took off in casual conversations with phone experts, or in phone firm stock prices. (Betting markets directly on these topics would have seen them. Alas we still don’t have such things.)

I’m happy to accept neuroscientist expertise, but mainly on in how hard it is to scan brain cells and model them on computers. This isn’t going to come up in casual conversation, but if asked neuroscientists will pretty much all agree that it should eventually be be possible to create computer models of brain cells that capture their key signal processing behavior, i.e., the part that matters for signals received by the rest of the body. They will say it is a matter of when, not if. (Remember, we’ve already done this for the key signal processing behaviors of eyes and ears.)

Many neuroscientists won’t be familiar with computer modeling of brain cell activity, so they won’t have much of an idea of how much computing power is needed. But for those familiar with computer modeling, the key question is: once we understand brain cells well, what are plausible ranges for 1) the number of bits required store the current state of each inactive brain cell, and 2) how many computer processing steps (or gate operations) per second are needed to mimic an active cell’s signal processing.

Once you have those numbers, you’ll need to talk to people familiar with computing cost projections to translate these computing requirements into dates when they can be met cheaply. And then you’d need to talk to economists (like me) to understand how that might influence the economy. You shouldn’t remotely expect typical neuroscientists to have good estimates there. And finally, you’ll have to talk to people who think about other potential big future disruptions to see how plausible it is that ems will be the first big upcoming disruption on the scale of the farming or industrial revolutions.