Information — facts, ideas, views — is spread via education, schools, personal communication, books, magazines and nowadays ever more the Internet. As I grew older I discovered much of it is false. That is: not true, not based on facts, not corresponding to reality. Over time I have learnt that spreaders of false information have a variety of reasons for doing so. Below is a summary.
On the elementary level there are two motives for spreading false information:
Both are harmful. Notice that in case 2. it is irrelevant whether or not the spreader believes the information is true. A more detailed discussion of causes of spreading false information follows. In reality these causes may occur in combination.
If someone is not intelligent enough to comprehend the matter he is dealing with, one may arrive at false conclusions and express false ideas. One will not change one's ways even when provided with the relevant correct information. There is no cure.
A misinformed person spreads false information because that person only has false information to start from. When the misinformed person comes across the relevant correct information, the person will change one's ways.
Sloppiness, hastiness, and other forms of lack of conscientiousness may cause information to be incorrect. A trivial but frequent cause.
The conformist expresses the views of one's environment, whether the conformist believes in them or not. Almost all groups use pressure and suggestion to conform members to a religious or ideological belief system, and the penalties for not conforming may be heavy. Many conformists are not aware of their conformism, and will therefore find the previous sentence hard to believe. They are asleep and dreaming so to speak. It is hard to awake them. They are as if under hypnotic suggestion, programmed to respond to the cue of taboo-breaking by reproving the non-conformist.
A personal, financial, political, or ideological interest may cause dishonest people to give false information. This occurs on the individual level, but is most serious on the level of large organizations. Governments, political parties, organizations in industry, ideology, charity, media and so on. Such organizations may have an interest in keeping the public misinformed about certain matters. And the larger the organization, the greater the interest.
The purposeful spreading of false information meant in the previous paragraph is often considered ethical by the spreaders, based on philosophical principles like "the effect of communication is more important than whether or not it is true what one communicates" and "there is no right or wrong, there are only consequences". Justification for such principles is found in certain branches of logic, mathematics, and philosophy, like "game theory" and "utility theory". Political movements on both the left and right wings of the spectrum employ this logic.
When delusions and hallucinations occur in a state of full psychosis it will be obvious to the observer that the information conveyed is not reliable. But sufferers from psychotic disorders are not always psychotic. They may have long periods of mental stability in between their psychotic episodes, and appear to function as undisturbed persons then. Sadly, mild delusions and hallucinations often persist throughout these periods of stability, and are not obvious to the average observer. A lot of false information in the realms of pseudo-science, the paranormal, alternative healing et cetera, has its origin here. The determination they display in defending or trying to prove their views has to do with an overwhelming fear of admitting (to themselves) they are mentally ill.
Ideas expressed under the influence of recreational drugs are often false. Drugs reduce intelligence and critical judgment, while giving the illusion of the opposite. Some even cause hallucinations. Heavy or very frequent users, and those who have been heavy users in their teenage years, remain in this state permanently.
Some are more concerned with being against the grain than with being right. This is the opposite of conformism. They may express both true and false ideas with equal conviction, as long as those ideas are violating some widely held notion or dogma.
Who works in isolation, out of touch with reality and not receiving appropriate feedback, may eventually develop false ideas even in the absence of any of the other causes mentioned in this article. This is similar to the fact that animals on remote islands, over millennia, develop features that would not be fit for survival elsewhere in the world.
The absence of critical inquiry leads one to believe and pass on false information. Aspects hereof are misunderstanding the "placebo effect", misunderstanding the mechanism of superstition, underestimating the probabilities of perceived "meaningful" coincidences, and underestimating the number of possible "meaningful" coincidences that could occur in a given situation. Skepsis can be learnt by some. Skepsis is required, but not sufficient, to find the truth.
People can be forced into providing false information. This is always extremely serious. The threatener is obviously the true culprit in these cases; scum of the lowest kind that must be removed from society for good.
The first step is to wonder if any of these causes are operating in oneself. This may partly fail as it is inherent to some of the causes that one is blind to them in one's own case. Next, one applies the same procedure to any information from others one encounters. In others it is easier to recognize the causes. Eventually one may see oneself mirrored in others and thus identify all the causes of false ideas in oneself. Thus, one becomes better at eliminating false information.