Supplementary Materials

The scope of human experience

This report discusses the scope of human experience – the cumulative memories of every person who has ever lived. Estimates of the amount of time people have spent doing various activities rely on estimates of the size of the human population throughout history.

What was the deadliest natural catastrophe?

Knowing what kind of catastrophes humanity has suffered in the past may provide us with some insight into how likely we are to experience them in the future. This report reviews the existing evidence on how many people were killed by three past historical catastrophes–the Black Death, the Plague of Justinian, and the Spanish Flu–as well as two, unknown pre-historic events. The report compares these figures to estimates of global population to suggest which event killed the largest proportion of humanity at the time.

Vertebrate neuron counts

Why count vertebrate neurons? Since at least some animals merit moral consideration, evaluating whether the world is, on net, good or bad requires one to consider the wellbeing of animals other than humans. But perhaps not all animals merit equal consideration. Although this issue is controversial to say the least, many people would feel worse about harming an elephant than they would a tadpole.

How have global population and GDP per capita changed over human history?

This report surveys existing research on global population and global economic growth over the course of human history. These features are important from a longtermist perspective because they may inform forecasts of the likely future trajectory of human civilisation, and help us understand the relative effectiveness of different levers on civilisational progress. We can also use them to form a more accurate picture of how human civilisation has developed so far. They help us understand how many lives transpired in any given historical period, and the conditions in which they were lived.

The Significance, Persistence, Contingency Framework

The world, considered from beginning to end, combines many different features, or states of affairs, that contribute to its value.1 The value of each feature can be factored into its significance—its average value per unit time—and its persistence—how long it lasts. Sometimes, though, we want to ask a further question: how much of the feature’s value can be attributed to a particular agent’s decision at a particular point in time (or to some other originating event)? In other words, to what extent is the feature’s value contingent on the agent’s choice? For this, we must also look at the counterfactual: how would things have turned out otherwise?

Superforcasting Long-term Risks and Climate Change

Good Judgment’s Superforecasters analyzed 22 questions related to the long-term risk of climate change. The questions were presented to the Superforecasters under the following categories: future levels of emissions, number of deaths caused by severe weather events (heat, storms, floods, and drought), food (cereal yields and food prices), future of the Amazon biome, cost of solar energy, and the risk of extinction where climate change is a cause thereof. These questions were examined first through a narrower set of objectively falsifiable forecast metrics, followed by a wider discussion of the overarching questions and alternative scenarios.

Climate Change & Longtermism

Climate change is a proof of concept of longtermism. Every time we drive, fly, or flick a light switch, each of us causes CO2 to be released into the atmosphere. This changes the amount of CO2 that is in the atmosphere for a very long time: unless we suck the CO2 out of the atmosphere ourselves, concentrations only fall back to natural levels after hundreds of thousands of years. This report evaluates the scale of climate change from a longtermist point of view.

Persistence: A Critical Review

This report reviews, replicates and extends the analysis from seven econometric papers studying how events that happened to and values held by our ancestors affect their descendants several generations afterwards (intergenerational persistence). The report argues that together the papers provide moderate evidence of the existence of long term causal effects mediated by parentage.

Potatoes: A Critical Review

This report analyzes a paper by Nunn and Qian, which studies the effect of the introduction of potatoes in the Old World on population growth between 1700 and 1900.

How violent was the pre-agricultural world?

Around 11,000 years ago plants and animals began to be domesticated, a process which would completely transform the lifeways of our species. Human societies all over the world came to depend almost entirely on farming. Before this transformative period of history, everyone was a hunter-gatherer. For about 96% of the approximately 300,000 years since Homo sapiens evolved, we relied on wild plants and animals for food. This report addresses the question: what do we know about how violent these pre-agricultural people were?

How many lives does the future hold?

The total number of people who have ever lived, across the entire human past, has been estimated at around 100 billion. The total number of people who will ever live, across the entire human future, is unknown – but not immune to the tools of rational inquiry. This report estimates the expected size of the future, as measured in units of ‘human-life-equivalents’. The task is a daunting one, and the aim here is not to be the final word on this subject. Instead, this report aspires to two more modest aims. First, to provide a robust defense of the claim that ‘the future is vast in expectation’:even on the conservative assumption that humanity’s future remains Earth-bound over the long-term, this report estimates that it can be expected to hold at least 100 trillion lives. The report’s second aim is to present an earnest, if somewhat more speculative, estimate of the true size of the future. This requires that we venture further from established research, meaning the associated estimate depends on several simplifying assumptions, and should be interpreted as less robust. Nevertheless, this report finds that the future is truly immense in expectation: on the order of 10^30 lives, or more than a billion billion times the total number of people who have ever lived.

AGI and Lock-In

The long-term future of intelligent life is currently unpredictable and undetermined. The report argues that the invention of artificial general intelligence (AGI) could change this by making extreme types of lock-in technologically feasible. In particular, it argues that AGI would make it technologically feasible to (i) perfectly preserve nuanced specifications of a wide variety of values or goals far into the future, and (ii) develop AGI-based institutions that would (with high probability) competently pursue any such values for at least millions, and plausibly trillions, of years.