Conspiracy lists a definition as: “an agreement by two or more persons to commit a crime, fraud, or other wrongful act.” 
Conspiracies happen. The assassination of President Lincoln was a conspiracy. Most internet scams are conspiracies. The Madoff Investment Scandal was a conspiracy. The Watergate scandal was a conspiracy. Price fixing is a conspiracy.  Real conspiracies are plausible and their motives are generally unsurprising. With real conspiracies, we rarely have to make unwarranted assumptions to accept them.
The complex and far reaching ones tend to fall apart like a house of cards when any part is exposed.

Conspiracy Theory

This is a pejorative term used to describe cynical and paranoid claims of conspiracy theorists. ‘Conspiracy Theory’ (as it pertains to medical issues) is another broad category of quackery after ‘Pseudoscience’ and ‘Denialism’.
Political scientist and author of A Culture of Conspiracy: Apocalyptic Visions in Contemporary America, Michael Barkun, defines ‘Conspiracy Theory’ as belief which explains an event as the result of a secret plot by exceptionally powerful and cunning conspirators to achieve a malevolent end.


Characteristics of Conspiracy Theories

A typical conspiracy theory attributes misfortunes to the sinister actions of powerful agents working in secret, rather than randomness or mistakes.  It rests on the assumption that such controlling agents are always at work to suppress good and feed on the weak. It gives an aura of simplicity and (usually) false certainty to complex and uncertain situations. Conspiracy theories often take an ‘all-good’ or ‘all-bad’ view of the world, leaving little gray area.
Conspiracy Theories tend to divide the world into 3 basic groups:
1. The “all-bad” conspirators (sinister agents that secretly control some or all aspects of society for profit and power)
2. The “sheep” (the general public that is unaware that they are being controlled by the conspirators; skeptics are generally acused of being sheep)
3. The ‘all-good’ mavericks, or ‘Truth Seekers’ (these are the conspiracy theorists themselves who feel that they alone can see through the facade of the conspiracy and must protect the public).
A conspiracy theorist may attribute the conspirators with incredible skill, intelligence, vigilance and power. The conspirators allegedly aim to suppress the truth about events or schemes of the conspiracy. They keep us in the dark such that we do not even realize that we are being controlled. If necessary, the conspirators will mobilize a campaign of misinformation to keep us ignorant of the truth.
The conspiracy theorist is often heard saying something to the effect of, “Hey, I’m just asking questions!” David Aaronovich describes this red flag in his book Voodoo Histories: The Role of Conspiracy Theories in Shaping Modern History. The theorist often points out anomalies in the data in the form of questions like, “How do you explain that? Huh?”  When experts give legitimate answers to these questions, the theorist seems to shrug them off and go on to the next list of questions that he/she is “just asking.”
Michael Shermer describes a conspiracy theory as being very complex such that its success would depend on a large number of unlikely elements and a large number of people all working secretly. The more people that would be required to keep such a conspiracy secret, the more unlikely the theory is to be true. 
The evidence for the conspiracy presented by the conspiracy theorist tends to be highly circumstantial. It may stem from some kernels of truth (e.g. big companies and governments do behave unethically at times). However, these generally accepted truths are extrapolated far beyond what the evidence or logic warrants. There appears to be a host of cognitive biases and logical fallacies at work, including confirmation bias which motivates theorists to cherry-pick data and anomoly hunt for any evidence that supports the theory. All disconfirming evidence, no matter how overwhelming, is ignored, discarded or explained away.
In fact, any evidence that coheres with the conspiracy theory is touted proudly. The structure of the supporting arguments for conspiracy theories generally take the form of arguments in series or arguments in convergence (see Argumentation and Logic) in that no one piece of evidence can support the theory alone. The theorist presents this data with a “veneer of scholarship” (as described by Aaronovitch in his book). They may present page after page of technical details with copious footnotes. A challenger may feel overwhelmed by the sheer amount of ‘evidence’ that they are presented with, most of which will be unverifiable during a debate (Argument Verbosium). 
A built-in part of a conspiracy theory is that skeptics of the conspiracy are part of the conspiracy. Those who challenge the theory by presenting disconfirming evidence are automatically labeled as being a conspirator or ‘shills’ for the conspirators. Challenges are often dismissed with statements akin to, “Of course the ‘expert’ is going say it is not true. That’s just what they want you to think!” Therefore, no amount of contrary evidence can convince a conspiracy theorist that the theory is wrong. Evidence against the conspiracy actually gets twisted into evidence for the conspiracy!  The logical fallacy at work here is the proof by lack of evidence fallacy. This is a form of special pleading called the ‘self-sealing fallacy‘ in that it ‘seals’ the argument by  rendering the conspiracy theory unfalsifiable in a debate.
Pseudoscience advocates and science denialists often appeal to conspiracy theory to defend themselves as mavericks fighting for truth against an establishment that is conspiring against them. 


Belief in conspiracy theories is quite common. A recent study by Public Policy Polling reported the following:
37% of voters believe global warming is a hoax
21% of voters say a UFO crashed in Roswell, NM in 1947 and the US government covered it up
28% of voters believe secretive power elite with a globalist agenda is conspiring to eventually rule the world through an authoritarian world government, or New World Order
20% of voters believe there is a link between childhood vaccines and autism
7% of voters think the moon landing was faked
14% of voters say the CIA was instrumental in creating the crack cocaine epidemic in America’s inner cities in the 1980’s
9% of voters think the government adds fluoride to our water supply for sinister reasons (not just dental health)
4% of voters say they believe “lizard people” control our societies by gaining political power
51% of voters say a larger conspiracy was at work in the JFK assassination, just 25% say Oswald acted alone
 15% of voters say the government or the media adds mind-controlling technology to TV broadcast signals (the so-called Tinfoil Hat crowd)
5% believe exhaust seen in the sky behind airplanes is actually chemicals sprayed by the government for sinister reasons
15% of voters think the medical industry and the pharmaceutical industry “invent” new diseases to make money



“Patternicity” and “Agenticity” are terms described in Shermer’s The Believing Brain that describe our natural tendency to seek patterns in nature out of random data and assume that those patterns have a conscious will.  We are pattern-seeking animals. We are particularly motivated to assume that patterns may be linked to things that will harm us. To a hunter-gatherer, if a pattern happens to be real, then recognizing it can be life-saving, while failing to recognize it can lead to falling victim to predators or going hungry. If the pattern is not real, then there may be some time wasted, but generally not much is lost. 

We also tend to attribute these patterns to motivated agents that may wish to harm us. Again, our hunter-gatherer ancestors had dangerous animals and hostile competitors to worry about. The side-effect of this is the assumption that dangerous things happen because such agents actually want to harm us (including things like floods, lightning, fires, etc). This ‘model’ of reality may have given our ancestors a survival advantage. 
We see these components at work in conspiracy theory. 
Epistemic bias appears to play a role. Epistemic bias is the cognitive bias that leads people to think that significant events have significant causes. For instance, a small power outage may be disregarded. However, the great blackout of 2003 caused immediate speculation about conspiracies of terrorists and government plots. A Google search for “Blackout of 2003” + Conspiracy yields over 1,300,000 results. Also, studies have shown that people place more significance on events that happened than on events that almost happened. A scenario in which an assasination attempt was botched seems to have less conspiratorial significance that one that was successful. 
Conspiracy theory allows conspiracy theorists to have a higher sense of self-worth in that they feel smarter than the ‘sheep’ and can see through the conspirators. They see themselves as being firmly on the ‘all-good’ side of their binary model of the world. 

Evaluating the Logic of Conspiracy Theories

When one is faced with an apparent conspiracy theory, it would behoove one to ask the following questions (see Skeptical Tools).

– Does accepting the theory violate Occam’s Razor? 

When faced with 2 or more competing explanations for an event, it is always best to go with the one that requires the fewest assumptions (especially if the assumptions are unfounded, unknowable or extraordinary). 
What would we have to accept as true for the conspiracy theory to hold up? This is similar to the first question. How many people would be required to make the conspiracy work and remain quiet about it? How long would a large group of people have to have been quiet about the conspiracy?  Are the motives plausible? Are the proposed methods plausible? How advanced and expensive would the technology have to be to make the conspiracy work? The answers to these questions are the assumptions that would be necessary for a large conspiracy to hold up.

– Are there violations of the Extraordinary Claims Axiom (Reverses the Burden of Proof)?

Are the proponents making allegations without extraordinary evidence? It is easy to drop a claim. The truth of a claim should be proportioned to its evidence. Are the proponents challenging us to prove them wrong? Remember, the burden of proof lies with the one making the extraordinary claim.
The questions are related. An extraordinary claim may be one that requires many assumptions to be accepted. Of course, if some of those assumptions are not very plausible, then that would further decrease the likelihood that the claim is true. We should always be wary of this.

Medical Conspiracy Theories

Many medical conspiracy theories hinge on fact:  the healthcare / pharmaceutical industry profits from treating illness. It is also a fact that the pharmaceutical industry has not always behaved ethically when marketing drugs to the public. These truths spawn an understandable distrust among the public. This distrust provides a wedge for conspiracy theorists to create an anti-science bias. Remember, our biases prevent us from knowing if we are committing Type 1 or Type 2 errors. Skeptical doctors must become proficient at critical thinking and understand the methodologies of science to minimize these errors.

The medical conspiracy theory argument implies that the industry wants to keep people chronically ill so that they will need to buy its products. For instance, some claim that we could cure AIDS, or cancer if we really wanted to, however that would sever the flow of profits from selling antiretroviral drugs and chemotherapy. Similarly, medical conspiracy theories claim that companies willingly promote products despite knowing that they are harmful, but then suppress the knowledge of harm to maximize profits.

One problem for the skeptic is that pharmaceutical companies really do profit from selling such treatments. It is also true that companies have not always behaved ethically in the past in selling these products. Companies have been caught suppressing harmful data. Thus, it is easy to cherry-pick circumstantial evidence and examples in support of the theory.
Such arguments make a number of assumptions. First, they assume that each company is run by truly evil people; people who do not want to see illnesses cured in their family members or even themselves. They assume that nocompany with a ‘cure’ would not gladly promote it, thereby  virtually wiping out its competition. They assume that not one person (of the thousands of people that would need to make such a conspiracy work) is willing to blow the whistle. They assume that governments with heavy financial healthcare burdens would not welcome the chance to decrease this burden by supporting companies that can cure chronic diseases.
Which claim makes the fewest assumptions? Is it the claim that the entire industry is purposely suppressing cures for chronic diseases? Or is it the claim that companies are capitalizing (albeit sometimes unethically) on providing treatments that have been shown to help?
Medical conspiracy arguments such as these often come from promoters of unproven treatments. They would have people believe that the healthcare industry conspires to suppress their products. Cures that “they don’t want you to know about” is a commonly used phrase. However, if financial gain is the motive of such conspiracies, one has to question the financial motives of the promoters of unproven treatments. We learned in the Pseudoscience section that pseudoscientists often appeal to conspiracy and claim that their work is being suppressed by the establishment.
Who is making the most extraordinary claims? Promoters of unproven therapies make extraordinary claims simply by definition. Claiming that something works when there is no scientific evidence makes the claim extraordinary. The burden of proof lies with the promoters of unproven therapies.
Other medical conspiracies involve governmental plots that use medical / chemical / biologic means to control populations. For instance, there have been increases in polio cases in Africa mainly due to conspiracy theory. Islamic clerics in Kano state condemned immunization campaigns as an American plot to make Muslim women infertile. It has been claimed that HIV was manufactured for the purpose of genocide against certain populations as a means of control. Others hold that the government and the airline industry conspire in a sinister plot to poison us all by deliberately spraying poisons into the air through the “chemtrails” of passenger jets (the contrails seen in the sky behind jets). Similarly, water fluoridation conspiracy theory accuses the government of deliberately poisoning the water in an effort to control us.
Again, we must ask ourselves if the assumptions inherent in these ideas are warranted.  If not, would it not be best to assume the null hypothesis until such warrants can be shown? Also, what extraordinary evidence is there for the extraordinary claim?


Conspiracy theories are claims. They make many assumptions, none-the-least-of-which is that most (if not all) people in high levels of power are truly evil with sinister motives. This is different from the obvious corruption that is frequently exposed and rarely surprising. There are enough real-world examples of actual conspiracies to fuel the seemingly endless barrage of unlikely conspiracy theories. Most tend to self-destruct in due time because the assumptions that are needed to keep them going are unlikely to hold up. Conspiracy theories stem from our psychology. They help us make sense of what seems like senselessness. They give us a sense of control and a feeling of being ‘in’ on a secret. They confirm the pessimistic world beliefs of those who hold them. While understandable, they give skeptical doctors reason to stay skeptical.
John Byrne, M.D.

References and Links

“List of conspiracy theories – Wikipedia, the free encyclopedia.” 2004. 
“Who needs facts? These vaccine conspiracy pieces write …” 
“Debunking Conspiracy Theories In ‘Voodoo … – National Public Radio.” 2010. 
“What are conspiracy theories? – UK-Skeptics.” 2006. 
“Conspiracy Theorists: Is the Truth Out There? | Psychology Today.” 2010. 
“Field Guide to the Conspiracy Theorist: Dark Minds | Psychology …” 2009. 
“here – Public Policy Polling.” 2013.
“The Psychology of Conspiracy Theories –” 2007. 
“The truth is out there – Vol. 23, Part 7 ( July 2010) – The Psychologist.” 
“Ten characteristics of conspiracy theorists – a look into the … – Urban75.” 2006. 
“Michael Shermer » The Conspiracy Theory Detector.” 2010. 
“Is There a Conspiracy to Suppress Cancer Cures? – Quackwatch.” 2002.