Why I Don’t Believe in the Butterfly Effect, Part 3

Part 3 of 12: The Wrong Way to Disprove It

In this essay, I will describe the wrong way to disprove the butterfly effect, while in Part 4, I will explain the right way to disprove it.

I am far from the only person who doesn’t believe in the butterfly effect. But among those of us who reject it, I often hear an argument that I don’t agree with. I often hear people say that the butterfly effect isn’t real because the universe is only a little chaotic, not extremely chaotic. They say that it is true that relatively small changes can have a surprisingly large influence over time, but it is not so extreme that a butterfly flapping its wings in Brazil could create a tornado in Texas.

The people who make this argument are often smart, rational people. And while I agree with their conclusion — that the butterfly effect isn’t real — I do not agree with the argument they’re using to reach that conclusion. I have two problems with their reasoning.

First, I am suspicious that if your defense against chaos is to say that the universe is only somewhat chaotic rather than extremely chaotic, then as the evidence piles on, you may have to concede more and more, until you eventually reach the full extent of chaos theory, under which a butterfly in Brazil causes a tornado in Texas. After all, many mathematical models are chaotic to the extreme, and if you employ deterministic models to predict the weather — or anything else — then you will probably end up with extreme chaos. (To be fair, scientists don’t always use deterministic models.)

Second, this argument is overlooking the most fundamental problem with the butterfly effect. The fundamental error behind the butterfly effect has nothing to do with meteorology or physics or computer models. It has to do with philosophy and logic. The butterfly effect is not a scientific fallacy; it is a logical fallacy. I will explain this in my next essay, Part 4.

Other parts of this series:

Part 1: An Introduction

Part 2: The Butterfly Effect in Pop Culture

Part 4: My Central Argument

Part 5: Responding to Arguments in Favor of the Butterfly Effect

Part 6: Exceptions (And Why They Aren’t Really Exceptions)

Part 7: Three Wrong Ways to Discuss Alternative History

Part 8: The Right Way to Discuss Alternative History

Part 9: How I Would Interpret Lorenz’s Observations

Part 10: The Butterfly Effect and the Slippery Slope

Part 11: Why I Care about This Topic

Part 12: Conclusion