Book Review - "The Demon-Haunted World" by Carl Sagan

Astronomer Carl Sagan’s 1996 book, The Demon-Haunted World is the ultimate guide to critical thinking. Carl Sagan asks, “How can we make intelligent decisions about our increasingly technology-driven lives if we don’t understand the difference between the myths of pseudoscience, New Age thinking, and fundamentalist zealotry…and the testable hypotheses of science?”

Sagan offers a lengthy explanation of how the scientific method works, and how it is demonstrably more successful than any of its pseudoscientific imitators. He teaches the importance of having a skeptical worldview, especially of extraordinary claims. As he stated in Cosmos, “Extraordinary claims require extraordinary evidence.” Sagan explains the necessity of Ockham’s Razor – the rule of thumb that people should not assume anything that the evidence does not require them to assume – in critical thought. He systematically exposes the absurdity behind many of the most popular modern-day forms of pseudoscience, including astrology, homeopathy, psychics, alien abductions, Freudian psychoanalysis, doomsday predictions, graphology, and numerology.

While some have criticized the book as being anti-religious, Sagan himself disputed this characterization. He was clearly an agnostic, but had a deep appreciation for the sense of wonder that religion could inspire and recognized that it had much in common with his own appreciation for science. He does take certain religious views to task – such as the ideas of young-earth creationism, faith healing, and divine intervention. However, he notes that although “religions are often the state-protected nurseries of pseudoscience…there is no reason why religions have to play that role.” Sagan was a strong advocate of finding common ground between the religious and scientific communities: a central theme of his novel Contact.

14 years after its original publication, The Demon-Haunted World seems more topical than ever. The applications of critical thinking extend far beyond the realm of science. By being skeptical of unusual claims, we can better gauge the veracity of some of the odd statements we routinely hear from any authority, including our politicians, educators, corporate gurus, and religious leaders. In my opinion, there is no more important skill that our schools should teach students than the process of thinking critically. Unfortunately, most high schools and many universities don’t offer any classes in critical thought, even as electives. Carl Sagan’s The Demon-Haunted World can guide us where our schools do not.

The Demon-Haunted World was Sagan's last book before his death in 1996. Although it never reached the same level of popularity as some of his other works such as Cosmos and Contact, I think it is his most important work for the layperson. The Demon-Haunted World has shaped my view of the world more than any other book.

5/5 stars

Rebuttal to the Simulation Hypothesis

According to Nick Bostrom’s simulation hypothesis, every universe’s inhabitants would be equally likely to be living in a simulation, even if they were running simulations of their own. This leads to the uncomfortable conclusion that our universe is much more likely to be one of a huge number of simulations, rather than the one parent universe.

From a logical standpoint, this argument makes sense to me. But I’m always eager to poke holes in philosophical arguments, so here’s my best rebuttal as devil’s advocate. It doesn’t directly attack the logic of Bostrom’s philosophy; rather, it creates a probabilistic argument that we are NOT a simulation.

Let’s assume that simulations can be “turned off” by the parent universe at any time. Perhaps the inhabitants decide that the simulation is no longer needed for whatever reason, or perhaps the simulation is accidentally destroyed, or perhaps they are in a simulation themselves which is turned off by their parent universe. If this is the case, it would break the simulation chain. If Simulation A was the parent of Simulation B, which was the parent of the Simulation C, which was the parent of Simulation D, the inhabitants of Simulation A would be able to break this chain and destroy all of the simulations in this chain by turning off Simulation B.

The simulation hypothesis concludes that we are in a simulation in all probability, and that every universe is equally likely to be a simulation. This means that the universe that begat ours is also probably a simulation, as is the universe that begat our parent universe. If this is the case, it would be very likely that our own universe is merely one node in a huge chain of parent universes.

But this creates an interesting question. If any of those universes could break the chain at any time by turning off their simulation, the probability that not a single one of them would do so must be extraordinarily low. This strongly suggests that we are not in a simulation.

There are a couple of responses to this argument which I can foresee, so allow me to preemptively address them. Some might invoke the Anthropic Principle. It doesn’t make sense to marvel at the unlikelihood of our own existence, they will reason, because if our universe had been turned off we wouldn’t be here to speculate about it. In my opinion, this is a flawed application of the Anthropic Principle because there is another plausible explanation for our existence: Our simulated universe hasn’t been “turned off” by any of its parents because they don’t exist. We are the original universe.

So we have two possible explanations for our own universe. Either we are in a simulation, and are here due to the infinitesimally unlikely whims of an unimaginably vast chain of parent universes…or we are simply not a simulation. If these are the two possibilities, the latter seems much more likely from this probabilistic standpoint. It also has the advantage of surviving Ockham’s Razor.

What do you think? Is my probabilistic argument for our actual reality as strong as Bostrom’s argument for our simulated reality? What flaws do you see in my logic?

Are we living in a simulation?

Are we living in a simulated reality? Transhumanist philosopher Nick Bostrom thinks so. He puts forth the following argument. One of the following three statements must logically be true: 1) Advanced civilizations can never develop simulated realities; 2) No advanced civilization would ever choose to develop simulated realities; or 3) Our own reality is almost certainly simulated.

There are a few circumstances in which Statement #1 could theoretically be true. Perhaps there are no other advanced civilizations in the universe. Perhaps advanced civilizations exist, but simulations are simply impossible. Or perhaps they are possible, but beyond the technological capacity of any species. I think Statement #1 is the least plausible of the three. As I mentioned in a previous blog post, even extremely pessimistic interpretations of the Drake Equation should have yielded at least one other advanced civilization somewhere in our universe. The technological barriers to creating a simulation seem very small. We already have rudimentary virtual reality technology, and there is no fundamental reason why we shouldn’t be able to create all-encompassing simulations within a few decades. Since we’re nearly able to create them already, it seems unlikely that there are no other civilizations in the entire universe that are a few mere decades ahead of us.

Statement #2 involves speculation into the motives of other civilizations, of which we can’t possibly know anything. However, we do know about our own civilization and what motivates us. If humans develop this technology within a few decades, we will almost certainly make use of it, creating thousands upon thousands of simulations for entertainment or research. Therefore it seems very likely to me that Statement #2 is false.

This leaves Statement #3. If we have concluded that Statements #1 and #2 are false, Bostrom reasons that Statement #3 must be true. Why? Because there will be an enormous number of simulated realities. The probability that we find ourselves in the one parent universe, as opposed to one of the many simulations, must be vanishingly small.

The Simulation Hypothesis fascinates me, because it is one of the few rationales for the existence of some form of a god which I, an agnostic, do not think is easily refutable. Let’s examine the common rebuttals of the simulation hypothesis to see how much merit they hold.

Some have questioned the assumption that there is one parent universe and many simulations. If there are many parent universes and many simulated universes, critics reason, then the probability that we are in a simulation would not necessarily be quite so high. But I disagree. What are the implications of many parent universes capable of sustaining life and technology? Presumably EACH of them would be running many simulations, and thus it would not affect the probability of our being in a simulation much at all.

The most serious problem I see with the Simulation Hypothesis is that it has no empirical basis, and falls apart under the scrutiny of Ockham’s Razor. There is absolutely no conclusive evidence that we are living in a simulation. There may be a few teasing clues (e.g. the quantum world behaves suspiciously differently when we aren’t watching), but nothing substantive. However, I can see no obvious flaw in the logic of the Simulation Hypothesis. This leads back to an old philosophical debate between empiricists and rationalists: Can we determine reality through sound logic, without empirical evidence? I tentatively plant my flag on the side of the rationalists. Scientists frequently adopt a rationalist mindset when interpreting the Drake Equation or formulating string theory (despite absolutely no evidence for extraterrestrials or strings), but switch over to empiricist mode for topics like philosophy or theology. This seems to be a product of cultural bias. In my view, while we should always seek out evidence wherever possible, sound logic is often a sufficient (if inferior) substitute.

At the end of the day, I tend to lean toward the conclusion that Bostrom is correct: We are probably in a simulation. What do you think? Let me know if/where you think the logic of the Simulation Hypothesis is flawed, or any other examples of clues that would suggest a simulated reality.