The butterfly effect is a term used in Chaos Theory to describe how tiny variations can affect giant systems, and complex systems, like weather patterns. The term butterfly effect was applied in Chaos Theory to suggest that the wing movements of a butterfly might have significant repercussions on wind strength and movements throughout the weather systems of the world, and theoretically, could cause tornadoes halfway around the world.

What the butterfly effect seems to posit, is that the prediction of the behavior of any large system is virtually impossible unless one could account for all tiny factors, which might have a minute effect on the system. Thus large systems like weather remain impossible to predict because there are too many unknown variables to count.

The term "butterfly effect" is attributed to Edward Norton Lorenz, a mathematician and meteorologist, who was one of the first proponents of Chaos Theory. Though he had been working on the theory for some ten years, with the principal question as to whether a seagulls’ wing movements changes the weather, he changed to the more poetic butterfly in 1973.

A speech he delivered was titled, “Does the Flap of a Butterfly’s Wings in Brazil Set off a Tornado in Texas.” Actually, fellow scientist, Philip Merilees created the title. Lorenz had failed to provide a title for his speech.

The concept of small variations producing the butterfly effect actually predates science and finds its home in science fiction. Writers like Ray Bradbury were particularly interested in the types of problems that might occur if one traveled back in time, trailing anachronisms. Could small actions taken in the past dramatically affect the future?

Fictional treatments of the butterfly effect as applies to time travel are numerous. Many cite the 2005 Butterfly Effect film as a good example of the possible negative changes that small behaviors in the past could have on the future, if one could time travel. Actually, a better and more critically accepted treatment of this concept is the 2000 film Frequency. In the film a father and son communicate over time through radio waves and attempt to change the past for the good.

In human behavior, one can certainly see how small changes could render behavior, or another complex system, extremely unpredictable. Small actions or experiences stored in the unconscious mind, could certainly affect a person’s behavior in unexpected ways.

One looks at teen suicide for example, where no instance of previous depression has occurred. Loved ones are often left wondering what the many small factors were that precipitated a suicide. Further, people often agonize about the small details they did not see as possible factors for an unexpected suicide.

However, there are plenty of ways that such a behavior would be unanswerable according to the butterfly effect. Minute actions and experiences dating from childhood stored in the unconscious mind are not accessible when a person has died, and they may be hard to access without hypnosis or therapy when a person is living.

Whether used in science, fiction, or social sciences, the butterfly effect remains theory. However, it does seem a reasonable explanation for the unpredictability of events. As it relates to human behavior, it does suggest that even the smallest actions may have huge consequences for good or ill.