Header 1

Our future, our universe, and other weighty topics

Saturday, December 3, 2016

They Put a “Science” Sticker on Their Gossamer Threads of Speculation

When you hear the phrase “tribal folklore,” you probably think of some image such as members of a primitive tribe sitting around a campfire, while someone with a necklace of bones and a feather headdress tells a story such as “Once upon a time the sun god spat out the earth.” But tribal folklore can arise and flourish in the modern halls of American universities, where there exist tribes such as the small tribe of cosmologists. Below is the story of how some tribal folklore not only started to flourish, but experienced runaway growth, like some out-of-control kudzu.

Around about 1978, cosmologists (the scientists who study the universe as a whole) were puzzled by a problem of fine-tuning. They had figured out that the expansion rate of the very early universe (at the time of the Big Bang) must have been incredibly fine-tuned, apparently to one part in ten to the sixtieth power. This dilemma was known as the flatness problem.

Enter Alan Guth, an MIT professor. Guth proposed a way to solve the flatness problem. Guth proposed that for a tiny fraction of its first second (for less than a trillionth of a trillionth of a second), the universe expanded at an exponential rate. The universe is not expanding at any such rate, but Guth proposed that after a very brief instant of exponential expansion, the universe switched back to the normal, linear expansion that it now has.

This idea was extremely far-fetched from the moment it was proposed, particularly the idea of the universe making this sudden switch so quickly. But nonetheless Guth's idea became very popular among the small tribe of cosmologists. We can call this idea Guthism, and we can call the cosmologists who adopted it Guthists.

But there was a big problem with Guthism. Its early versions (as advanced in the early 1980's) simply did not work. They had all kinds of problems. The Guthists tried to fix this. First, they got busy creating hundreds of different versions of Guthist theories, all based on the idea that the universe had undergone an instant of exponential expansion. So instead of just one Guthist theory, before long there were hundreds of variant theories.

Some of these theories indulged in runaway speculations. One variation called eternal inflation imagined that our universe was just one bubble in an infinite sea of bubble universes. The advantage of this is that no matter improbable it might be that a universe might undergo a phase of exponential expansion and then change to the regular expansion we observe, a Guthist could say that such a thing would have happened at least once in the infinite sea of bubble universes.

We must take a step back here, and categorize the scientific status of Guthism.  Guthism is sold as science; its proponents have put a "science" sticker on their gossamer threads of speculation.

However, Guthism is best described not as science, but tribal folklore. It is a species of folklore that has become popular among the very small tribe of humans called cosmologists.

Below is the basic piece of folklore behind Guthism:

At the very beginning the universe started out with just the right conditions for it to start expanding at an exponential rate. So for the tiniest fraction of a second, the universe did expand at this explosive exponential rate. Then, boom, the universe suddenly switched gears, and started expanding at the much slower, linear rate that we now observe.

There is no evidence supporting this speculation, so it is quite accurate to call it a piece of tribal folklore. The actual expansion of the universe that we observe justifies no belief other than the belief that the universe has expanded at the same linear rate that we now observe it expanding at.

But our Guthists often mislead us about whether there is evidence for their Guthist folklore. Here is a very misleading statement recently made by Guthist cosmologist Ethan Siegel:

You see, we can extrapolate the Big Bang backwards to an arbitrarily hot, dense, expanding state, and what we find is that it didn’t get infinitely hot and dense early on, but rather that — above some energy and before some very early time — there was a phase that preceded the Big Bang, and set it up. That phase, a period of cosmological inflation, describes a phase of the Universe where rather than being full of matter and radiation, the Universe was filled with energy inherent to space itself: a state that causes the Universe to expand at an exponential rate.

This is a falsehood, as the Guthist theory of cosmological inflation (that the universe once expanded at an exponential rate) is not at all something that can be derived by any type of extrapolation. Extrapolating the universe's current expansion back to the very beginning of time in no way supports the conclusion that the universe underwent an exponential expansion of the type imagined by Guthists. Saying that extrapolation leads to exponential expansion (Guthist cosmic inflation) at the universe's beginning is like saying that you can extrapolate the motion of a baseball pitcher's fastball to calculate that it will end up in the exhaust pipe of your car, because the hitter may hit the ball out of the stadium, and the ball may bounce off the parking lot asphalt, landing in your car's exhaust pipe. The scientific papers of the Guthist theorists don't use extrapolation to set up the conditions for exponential expansion; they rely instead on speculations as ornate as the exhaust pipe speculation just given.

In the same post (entitled “Is There Another 'You' Out There in a Parallel Universe?”), Siegel sinks into the kind of runaway, out-of-control folklore that Guthists like to engage in, as when he says, “There are a huge number of Universes out there — possibly with different laws than our own and possibly not — but there are not enough of them to give us alternate versions of ourselves; the number of possible outcomes grows too rapidly compared to the rate that the number of possible Universes grows.” To the contrary, we have zero evidence for the Guthist claim of exponential expansion in the early universe, and zero evidence for any other physical universe other than our own.

One of the reasons why Guthism isn't really a scientific program is that it is neither based on observations nor does it make precise predictions that we can test. A New Scientist article puts it this way:

But no measurement will rule out inflation entirely, because it doesn’t make specific predictions. “There is a huge space of possible inflationary theories, which makes testing the basic idea very difficult,” says Peter Coles at Cardiff University, UK. “It’s like nailing jelly to the wall.”

The Guthist idea of exponential expansion was originally created to try to remove the precise fine-tuning needed to have the critical density of the universe match the actual density of the universe, to sixty decimal places. The thinking was kind of like, “Ugh, we don't like fine-tuning in nature, so let's try to get rid of it.” But the Guthist cosmic inflation theory requires its own fine-tuning to work – just as much or more as the fine-tuning it was designed to remove. Judging from a recent cosmology paper, Guthist claims require not just one type of fine-tuning, but three types of fine-tuning. The paper says, “Provided one permits a reasonable amount of fine tuning (precisely three fine tunings are needed), one can get a flat enough effective potential in the Einstein frame to grant inflation whose predictions are consistent with observations.” How on Earth does it represent progress to try to get rid of one case of fine-tuning by introducing a theory that requires three cases of fine-tuning? And the estimate of three fine-tunings in the paper is probably an underestimate, as other papers I have read suggest that 7 or more precise fine-tunings are needed.

This is not theoretical progress

In terms of actually advancing human knowledge, Guthism has been a bust for cosmology, a misadventure that future cosmologists will probably look back on with disdain. We have learned nothing about reality by these unverifiable speculations that the universe underwent an instant of exponential expansion during its first second. But Guthism has been very good for cosmologists themselves. This is because Guthism provides our cosmologists with an easy way of earning a paycheck, a nice meal-ticket. The modern cosmologist is supposed to write several scientific papers every year, and writing a Guthist paper on yet another variation of cosmic inflation theory is easy work for today's cosmologist. We cannot observe anything that happened before the recombination era that happened about 380,000 years after the Big Bang. So if you are a cosmologist, you can make a nice, safe living writing speculative papers about various weird physical possibilities during the universe's first instant; and no one will be able to disprove your speculations.

Let me describe a very simple method for distinguishing between a scientist who has actually discovered something and a scientist who is indulging in speculation, perhaps just giving you a little folklore of his science tribe. After the scientist discusses his pet doctrine, you just ask him or her: “What observations or experiments forced you to believe that?” In the case of a relatively solid finding such as the Big Bang, the scientist can give a good answer, by mentioning things like the discovery that galaxies are receding away from us, and the discovery of the cosmic background radiation around 1965. But in the case of the Guthist theory of exponential expansion of the universe during only a fraction of its first second, a scientist will have no decent answer to the question of, “What observations or experiments forced you to believe that?”

Tuesday, November 29, 2016

It's More Likely That Everything Is in Consciousness Than That Consciousness Is in Everything

In academic circles it is commonly assumed that consciousness is generated by the brain. But some philosophers have been dissatisfied with this idea. Why is it that some particular arrangement of matter would cause Mind (a totally different type of thing) to emerge from that matter? To many that seems no more plausible than the idea that some particular arrangement of crystals in a rock might cause the rock to gush out blood.

One alternate idea is to assume that we have something like a soul, and that our mental experiences are produced not just by matter (the brain), but something that is itself spiritual. Another alternate idea is the radical notion known as panpsychism. Panpsychism is basically the idea that consciousness is in everything.

A panpsychist might believe that every piece of matter is in some sense conscious. At first this may seem to help in explaining how brains can produce consciousness. If every neuron is a little bit conscious, it might explain why billions of cells in the brain can produce consciousness.

But it does not seem that there is any evidence that little pieces of matter are conscious. Electrons seem to behave with complete predictability according to the laws of electromagnetism, not as if they were semi-conscious little things with wills of their own. And oxygen molecules do not act as if they had some interest in their surroundings. When you enter an empty room, you do not feel a gush of wind coming your way, as you might feel if the air molecules were interested in seeing who was entering the room.

Panpsychism seems rather inconsistent with theism. Consider the moon. The idea that the moon is conscious may have a certain appeal. But imagine all those rocks on the moon's surface, lying there for billions of years. Think of what torture it would be if such rocks were actually conscious – they would have to suffer billions of years of absolute boredom, just sitting there with nothing to observe or experience. It would be hard to think of a reason why any deity would wish to endow such rocks with consciousness, to suffer such billion-year boredom and stagnation. And what about all the rocks and little pieces of matter underneath the surface of the moon and other planets, who would have the dullest experiences imaginable for billions of years?

I'm not sure we would want to believe that all the little pieces of matter around us are conscious. Do you want to believe that every time you walk on the autumn leaves, that you are crushing conscious beings underneath your foot? And if you accepted panpsychism, it would seem that every time you bake some cookies, you would have to worry about slowly torturing the poor conscious little cookies. 


An alternative to panpsychism, and something equally as radical, is the philosophical doctrine of idealism. Rather than maintaining that consciousness is in everything, an idealist maintains that everything is in consciousness.

An idealist maintains that the only thing that exists are different types of minds, and that material things only exist in the sense that they are elements within the mental experiences of minds. Perhaps the best way to explain this idea to the modern person is to consider what goes on in a video game. Suppose you are playing some Star Wars video game in which you are trying to blow up the Death Star. Now to what extent does this Death Star exist? It has no physical existence outside of the game world. The Death Star exists as a shared perception, something that is seen by all of the players of the video game under certain conditions. Similarly, an idealist may believe that Earth's moon has no physical existence outside of minds. According to such a person, our moon only exists as a shared perception within the mental experience of humans. An idealist thinks that if somehow all minds were to be destroyed, there would be no more moon.

So the idealist believes that the sole reality of physical things we perceive is their reality inside our minds. To such a person, the history of the universe is simply a history of mental experiences; and there was no state of the universe in which matter existed before minds.

There is no way to prove this philosophical doctrine, but there are no observations that we could ever have that would disprove this idea. Think about it. Every single observation or measurement we can make can be boiled down to a human experience. If you see a rock, that's a human experience. If you weigh the rock, that's also a human experience. If you measure the rock with a measuring rod, or determine its chemical content using a mass spectrometer, that's also a human experience. There is no way to verify that the rock exists outside of human experience.

Any credible theory of idealism requires a belief in some higher agent that acts to assure that there are certain consistencies in human experiences. But since idealism ends up removing quite a few dilemmas and difficulties in the “first matter, then mind” story of the universe, idealism ends up being at least as credible as any other philosophical worldview. A surprisingly compelling case for idealism was made in the 18th century by the British philosopher George Berkeley.

Today idealism is rather unfashionable, but in certain circles it is fashionable to speculate that we are just items in some computer simulation created by extraterrestrials. But the underlying concept is quite similar – that the things we perceive do not exist independently of our experiences, and that there is some external reality guaranteeing that we have certain common perceptions (such as the perception of the moon when we look up at night), rather than each of us having totally unique mental experiences.

But if you maintain that we are participants in some computer simulation crafted by extraterrestrials, you haven't removed any explanatory difficulties. The vexing problem is how is it that Mind can arise from matter, a totally different type of thing. With idealism such as advanced by Berkeley, that problem is removed, for you end up with the doctrine that there are only minds. But with some extraterrestrial simulation theory, the explanatory problem becomes twice as bad. For the theory maintains that biological matter gave rise to one type of minds (extraterrestrial minds), and that such minds then produced electronic matter that give rise to our minds. With that theory, you have two types of “Mind from matter” difficulties.

Both panpsychism and idealism are rather radical philosophical doctrines, and we are not forced to choose between the two. But if I had to choose between the belief that consciousness is in everything (panpsychism), and the belief that everything is in consciousness (idealism), I would choose the second of these. I don't care to believe that my cookies are suffering when I bake them.

Friday, November 25, 2016

How Not To Do a Meta-Analysis

I have no idea whether the esoteric practice known as homeopathy has any medical effectiveness, and this will certainly not be a post intended to persuade you to use such a practice. I will be examining instead the unfairness, methodological blunders and sanctimonious hypocrisy of an official committee summoned to convince you that homeopathy is unworthy of any attention. Committees such as this are part of the reality filter of materialists, the various things they use to try to cancel out, disparage, or divert attention from the large number of human observations inconsistent with their worldview. 
reality filter
Issuing a 2015 meta-analysis report on homeopathy, the committee called itself the Homeopathy Working Committee, and was sponsored by or part of the the National Health and Medical Research Council (NHMRC), an Australian body. The committee consisted of 6 professors and one person who was identified merely as a consumer.

On page 14 of the committee's report, the committee makes this confession: “NHMRC did not consider observational studies, individual experiences and testimonials, case series and reports, or research that was not done using standard methods.” What kind of unfairness is that? Using such a rule, if a committee investigating a medical technique were to receive a million letters saying the technique produced instantaneous and permanent cures of dire maladies, the committee would just discard all such letters and not let them influence its conclusion.

The committee limited itself to scientific studies, but it did not at all simply consider all of the scientific studies on homeopathy. Instead, the committee chose to disregard the vast majority of scientific studies on homeopathy, and consider only a small subset of those studies. This is made clear by a Smithsonian article on the committee's report, which says, “After assessing more than 1,800 studies on homeopathy, Australia’s National Health and Medical Research Council was only able to find 225 that were rigorous enough to analyze.” But what was going on was actually this: the committee cherry-picked 225 studies out of more than 1800, claiming that only these should be allowed to influence its conclusions. So it based its findings on only about 12 percent of the total number of scientific studies on the topic it was examining, excluding 88% of the studies. I have never heard of any meta-analysis that excluded anything close to such a high percentage of the studies it was supposed to be analyzing.

The committee claimed to have used quality standards, standards that relatively few of the studies met. What were these standards? Below is a quote from the committee's report.

The overview considered only studies with these features: the health outcomes to be measured were defined in advance; the way to measure the effects of treatment on these outcomes was planned in advance; and the results were then measured at specified times (prospectively designed studies); and the study compared a group of people who were given homeopathic treatment with a similar group of people who were not given homeopathic treatment (controlled studies).

It is not at all true that medicine or science has these criteria as standards that are followed by all or even most studies. Control groups are when you have some people studied who are not subject to what is being tested in another group. A large fraction of all scientific studies and medical studies do not use control groups, for various reasons. Controls are often not practical to implement, too expensive to implement, or not needed because it is clear what the result will be in the case of zero influence. This scientific paper says the following about control groups:

The proportion of studies that have control groups in the ten research domains considered range from 3.3% to 42.8% ..Across domains, a mere 78 out of the 710 studies (11%) had control groups in pre-test posttest designs.

It also is extremely common for medical and scientific research to report findings that the study was not designed to look for. Saying that a study must only report what it was designed to measure is a piece of sanctimonious rubbish, rather like claiming that good students must only get ancient history answers by reading the original ancient texts, rather than looking up the answers on the Internet. Under such a rule, we would for example ignore very clear findings that homeopathy was effective in reducing arthritis pain, if the study was designed to look for whether homeopathy was effective in reducing headaches. I have never heard of any meta-analysis excluding studies based on whether they reported unexpected findings the study was not designed to look for. This seems to be an aberrant, non-standard selection rule.

So what we have here is a committee using a double standard. It has declared that scientific studies will not be considered unless some particularly fussy standard is met, a standard that a large fraction of highly-regarded scientific studies do not meet. It's like the door guard of the country club saying “Ivy league graduates only” to dark-skinned people trying to get in, even though he knows he just admitted some white people who don't even have college degrees.

The statement below from the committee's report also is a sign of double standards and cherry-picking.

For 14 health conditions (Table 1), some studies reported that homeopathy was more effective than placebo, but these studies were not reliable. They were not good quality (well designed and well done), or they had too few participants, or both. To be confident that the reported health benefits were not just due to chance or the placebo effect, they would need to be confirmed by other well-designed studies with adequate numbers of participants.

On page 35 we learn that the actual participant size requirement used by the committee was a minimum of 150 participants (studies with fewer participants were ignored). So if there had been 500 studies each showing that between 110 and 149 patients were instantly cured of terminal cancer, such studies would all have been excluded and ignored. How silly is that? For comparison, a meta-analysis on stuttering treatments excluded only studies with fewer than 3 participants; a meta-analysis on diabetes excluded only studies with fewer than 25 participants; and a cardiology meta-analysis included studies with as few as 62 participants.

I very frequently read about scientific studies which used only a small number of participants (30 or less), studies getting lots of coverage in the media, after being published in scientific journals. So evoking “too few participants” as an exclusion criteria (based on a requirement of at least 150 participants) is another example of a double standard being used by the committee. And once a committee has declared the right to ignore any study that does not meet the vague, arbitrary, subjective requirement of being “good quality (well designed and well done)," it has printed itself a permission slip to ignore any evidence it doesn't want to accept.

Below is a page from a statistician's presentation on whether or not small sample sizes should be excluded when doing a meta-analysis of medical studies. The recommendation is the opposite of what the homeopathy study committee did.

Similarly, the “Handbook of Biological Statistics” site says, “You shouldn't use sample size as a criterion for including or excluding studies,” when doing a meta-analysis.

In the case of homeopathy, it's particularly dubious to be excluding small studies with less than 150 participants. Only a small fraction of the population believes in the effectiveness of homeopathy. It is entirely possible that because of some “mind over body” effect or placebo effect, homeopathy is actually effective for those who believe in it, but ineffective for those who don't believe in it. So we are very interested in whether it is effective for small groups such as a small group that believes in homeopathy. But we cannot learn that if a committee is arbitrarily excluding all studies with fewer that 150 participants.

No doubt if we were to examine the scientific papers of the professors in the committee, we would find many that had the same issues of small participant size or no control groups or reported effects that the study was not designed to show (or we would find these professors had authored meta-analysis papers that included studies that lacked one or more of these exclusion criteria). So it is hypocrisy for such a committee to be using such things as exclusion criteria.

Apparently the committee used some type of scoring system to rate studies on homeopathy. One of the subjective criteria was “risk of bias.” We can guess how that probably worked: the work of any researcher judged to be supportive of homeopathy would be assigned a crippling "risk of bias" score making it unlikely his study would be considered by the committee. But what were the scores of the excluded studies, and what were the scores of the studies that were judged to be worthy of consideration? The committee did not tell us. It's kept everything secret. The report does not give us the names of any of the excluded studies, does not give us URL's for any of them, and does not give us the scores of any of the excluded studies (nor does it gives the names, the URLs or the scores of any of the studies that met the committee's criteria). So we have no way to check on the committee's judgments. The committee has worked in secret, so that we cannot track down specific examples of how arbitrary and subjective it has been.

There is a set of guidelines for conducting a medical meta-analysis, a set of guidelines called PRISMA that has been endorsed by 174 medical journals. One of the items of the PRISMA guidelines is #19: “Present data on risk of bias of each study and, if available, any outcome level assessment.” This standard dictates that any subjective “risk of bias” scores used to exclude studies must be made public, not kept secret. The NHMRC committee has flaunted such a guideline. The committee has also ignored item 12 on the PRISMA guidelines, which states, “Describe methods used for assessing risk of bias of individual studies.” The NHMRC committee has done nothing to describe how it assessed a risk of bias. Nowhere do the PRISMA guidelines recommend excluding studies from a meta-analysis because of small sample size or whether the reported effects match the effects the study was designed to show, two aberrant criteria used by the NHMRC committee.

It has been recommended by a professional that whenever any meta-analysis uses a scoring system to exclude scientific studies on the topic being considered, that such a meta-analysis should always give two different results, one in which the scoring system is used, and another in which all of the studies are included. That way we could do a sensitivity analysis in which we can see how much the conclusion of the meta-analysis depends on the exclusion criteria. But no such thing has been done by the committee. They have secretively kept their readers in the dark, by revealing only the results obtained given all of their dubious exclusions.

After doing all of this cherry-picking based on double standards and subjective judgments, the committee reaches the conclusion that homeopathy is not more effective than a placebo. But even if such a thing were true, would that make homeopathy worthless for everybody? Not necessarily.

Here's the story on placebos. Placebos have repeatedly been shown to be surprisingly effective for certain conditions. A hundred years ago, your doctor might have given you a placebo by just handing you a bottle of sugar pills. But nowadays you get your medicine in labeled plastic containers at the pharmacy, and people can look up on the Internet anything that is on the label. So a doctor can't just write a prescription for sugar pills without the patient being able to find out it's a placebo. But if a patient thinks some particular thing will work – homeopathy, acupuncture, holding a rabbit's foot, praying, or meditation – that might act as a placebo with powerful beneficial effects. 

We therefore cannot dismiss something as being medically ineffective by merely saying it's no better than a placebo. Imagine there's a patient who doesn't trust pills, but who tends to believe in things like homeopathy. Under some conditions and for certain types of patients, homeopathy might help, even if what's going on is purely a “mind over body” type of placebo effect, rather than anything having to do with what is inside some homeopathic treatment.

If there are “mind over body” effects by which health can be affected by whether someone believes in a treatment, such effects are extremely important both from a medical and a philosophical standpoint, since they might be an indicator that orthodox materialist assumptions about the mind are fundamentally wrong. Anyone trying to suppress evidence of such effects through slanted analysis shenanigans has committed a grave error.

Based on all the defects and problems in this committee's report, we should have no confidence in its conclusion that homeopathy is no more effective than placebos; and even if such a conclusion were true it would not show that homeopathy is medically ineffective (since placebos can have powerful medical effects). `The fact that 1800 studies have been done on homeopathy should raise our suspicions that at least some small subgroup is benefiting from the technique. It doesn't take 1800 studies to show that something is worthless – one or two will suffice.

Whether homeopathy has any medical effectiveness is an unresolved question mark, but about one thing I am certain. The committee's report is an egregious example of secretiveness, double-standards, overzealous exclusions, guidelines violations, and sanctimonious hypocrisy. Using the same type of methodological mistakes, you could probably create a meta-analysis concluding that smoking doesn't cause lung cancer; but you would mislead people if you did that. 

Postscript: Today's New York Times criticizes "the cult of randomized controlled trials" and points out the case of those who say the evidence for the effectiveness of flossing is weak, because there aren't enough randomized controlled trials showing it works. That, of course, makes no sense, as we have abundant anecdotal evidence that flossing is effective -- just as we have abundant evidence that parachutes work, despite zero randomized controlled trials showing their effectiveness. 

Monday, November 21, 2016

The Errant Experts Who Cry "Impossible!"

The controversial EmDrive device offers a hope of a revolutionary new method of space travel that could greatly shorten trips to the Moon and Mars. It's a propellantless propulsion device. Even after sizable evidence had accumulated that the device did indeed work, various scientists declared that it is “impossible,” that the device could not work. Now (as discussed here) a new peer-reviewed scientific paper has found that the EmDrive device does indeed work, providing a significant thrust. 

An EmDrive device

How could so many physicists have got it wrong? An example was Cal Tech physicist Sean Carroll, who had this to say last year about the EmDrive:

The more recent “news” is not actually about warp drive at all. It’s about propellantless space drives — which are, if anything, even less believable than the warp drives....The “propellantless” stuff, on the other hand, just says “Laws of physics? Screw em.” ….What they’re proposing is very much like saying that you can sit in your car and start it moving by pushing on the steering wheel....There is no reason whatsoever why these claims should be given the slightest bit of credence, even by complete non-experts.

Carroll's blunder is an example of a type of misfire we have seen again and again. Once upon a time, scientists discovered a few assorted facts about nature, a few pieces of the vast cosmic puzzle. Soon thereafter, the heads of our scientists started to swell like balloons. They started depicting themselves as great lords of knowledge, who had learned enough to issue pronouncements such as This is the way that nature always behaves or That type of behavior is forbidden by nature. Such pronouncements are usually just bombast and bluster, and are often no more reliable than the pronouncements of sectarian theologians.

Here is what is typically going on when a scientist says something is impossible:
  1. A scientist assumes that some particular unproven assumption (call it assumption X) is true, largely because such an assumption is popular among his colleagues.
  2. The scientist then considers some proposed phenomenon (call it phenomenon Y), and judges that such a phenomenon cannot be occurring if assumption X is true.
  3. The scientist then declares that phenomenon Y is impossible.
Such a declaration of impossibility is usually dubious, because it relies on unproven assumptions. If such assumptions are wrong, the “impossible” phenomenon may be perfectly possible.

An example of such a declaration of impossibility occurs when a scientist declares telepathy or extrasensory perception (ESP) to be impossible (despite compelling laboratory evidence for its existence). Below is what is going on:
  1. The scientist assumes that a particular unproven assumption is true, the assumption that the human mind is purely the result of brain activity, largely because this assumption is popular among scientists.
  2. The scientist then considers the possibility of telepathy, and judges this to be impossible if humans minds are purely the result of brains, based on the difficulty of signals passing out of the brain and traveling through the skull.
  3. The scientist then declares that telepathy is impossible.
But the reasoning is invalid because the first assumption is not only unproven but actually extremely dubious. We are not entitled to conclude with any confidence that our minds are purely the product of brains, because (as discussed here) we have no understanding of how 50-year old memories could possibly be stored in brains, which are subject to such high structural and molecular turnover that memories should not be able to last for more than a year. Nor do we have any understanding of how brains could possibly achieve the instant recall of obscure memories that our minds display. We are told this involves molecular actions, but complex molecular reactions occur way too slowly to account for obscure memories that are retrieved in half a second (as we see happening on television shows such as Jeopardy). It takes a minute for cellular molecules to transcribe a single protein from the data in DNA, so how many minutes would it take to read some memory stored in brain molecules? Then there's this problem: how on earth could a brain ever know where some particular memory was stored inside it? Don't tell me your brain searches through your neurons, because that would take way too long to account for obscure memories that are retrieved by quiz show contestants in half a second.

It short, claims of the impossibility of telepathy rest on utterly dubious dogmas about the source of the human mind, dogmas that no scientist could be justified in proclaiming until he can give a detailed plausible story of how our brains might be able to store memories for 50 years, and also instantly retrieve them (something our scientists are nowhere close to doing).
A particularly errant creature is the scientist who assures us that there is “no need” for him to examine evidence in favor of some phenomenon that he has declared to be impossible, on the grounds that it conflicts with some cherished unproven assumption of the scientist. By such strange pretzel logic, such a scientist may try to print himself a permission slip for ignoring the very evidence that he should have evaluated before even making the unproven assumption.

Let's look at some examples of some things that one might be regarded as “scientifically impossible,” but which are actually no such thing. An example is the levitation of a material object or a human body. Science has merely established that there must be a downward gravitational force acting on a body positioned on a planet. But science in no way guarantees that there will not be an upward force (material or immaterial) acting underneath such a body, pushing it up with a force exceeding the downward force of gravity. So levitation is not actually impossible, and could be achieved through various means. Of course, humans are actually levitated in some tornadoes.

Other examples of things sometimes said to be scientifically impossible, but not actually so, include things such as sudden cures, mind-over-matter, apparitions, and life after death. No such things violate any known law of nature that can be specified, so they are not impossible. Arguments attempting to show the impossibility of such things always boil down to: I presume that nature works in this particular way; but if nature does in such a work a way, that thing could not occur; therefore, that thing is impossible. Such reasoning has little weight, because our understanding of how nature works is paltry and fragmentary. Contrary to the overconfident bluster of so many scientists, we have a very good understanding of neither life nor Mind; and we don't even understand most of the material substance in the universe. How can we claim to understand nature well, when something as simple as the vacuum of space is a great thorn in the side of the modern physicist, having a nature completely different from that predicted by theoretical quantum considerations? And if we don't understand something as simple as a vacuum, what pretentious hubris is it for us to act as if we understand such infinitely more complicated things as biological life and Mind?

Postscript: We can put down cosmologist Ethan Siegel as another scientist who just won't accept the EmDrive results (based on what he says here).