I used to spend a lot of time over my grandmother's house when I was little. One Sunday, I was over her house watching a cartoon called Banana Man on Nickelodeon. I hadn't really watched it before but hey, it was my grandmothers house, it wasn't like there was a lot to do there. My stomach started to grumble so I went to the bathroom and proceeded to throw up. And then I threw up again. And again. My grandmother came rushing in and I just couldn't stop throwing up. I don't remember the exact timeline after that, but I do remember my mom picking me up and taking me directly to the doctor where they gave me the requisite shot in the butt. Because that's what every kid wants after spending the past hour puking.
After that experience, I refused to watch Banana Man again. To my simple mind, the relationship was direct. I had never watched that cartoon before, and when I did, I got really sick and needed a shot in the butt. Since I didn't wish to repeat that sequence of events, I simply avoided watching the cartoon. I can easily look back as an adult and see how silly my thought process was but at the time it made perfect sense to me. Part of our soul demands that we investigate our situations and it's in our nature to look for this cause and effect relationship. The problem is that we often see this relationship where it doesn't exist.
Our minds are linear in nature; we just can't perform multiple voluntary acts at the same time very well. Whenever we're doing more than one thing, it's because all but is involuntary: breathing, digesting, blinking. We cannot simultaneously figure out two different puzzles; we can't carry on two different converations at the same time. When we're demanded to multi-task, we do so in a round robin way to create the illusion that we're doing multiple things at once. In reality, we're doing a single thing then stopping and doing another single thing and carrying on until all activities have been covered. Then we start again. We are linear.
Cause and effect defines a linear relationship between two points in time. Since our minds are inherently linear, this relationship makes perfect sense and so we look for it everywhere. If I had turned left instead of right, I wouldn't have been late; if I had approached her in a different way, she would've gone out with me. Our minds oversimplify reality into this linear relationship because otherwise it would be too difficult to disect. The problem is that reality is very non-linear.
At any given point in time there are any number of events occuring. The non-linear nature of reality is hard to fathom and even harder to explain. Our minds simply can't operate in the number of dimensions necessary to firmly grasp exactly why one thing happened and another did not; there are simply too many variables. So we simplify, and that's when we run into problems. My belief that a cartoon had made me sick is clearly wrong, but because the uniqueness of the situation was complete, my mind could easily make that jump. New cartoon is followed by being sick in a new way...it seems to make sense.
As my brother is fond of saying, correlation doesn't indicate causation. The fact that two events occur in close proximity to one another doesn't mean that there exists a relationship between them. Yet we draw those conclusions all the time. And then we drive ourselves crazy trying to switch up the variables to figure out if a different result could have been achieved. In doing so, we'll misidentify the cause expecting that its change will alter the effect. But the non-linear nature of reality doesn't really let you know the original cause.
Science tries to identify the cause through repetition, believing that achieving a given effect by following a specific sequence of events points more directly to the truth. By repeating the cause then the effect should also repeat...yet it doesn't always. And so medications come with warnings about side effects that have been observed but can't be traced to a specific cause, and some people are deathly allergic to peanuts while others enjoy peanut butter and jelly sandwiches on a daily basis.
When dissecting a cause and effect relationship, it's important to remember that you don't have all of the information. The closest you can really get to a true relationship is to a define a "most of the time" series of events. There's no such thing as absolutes in the universe, everything is relative and in constant motion. Don't let linear thinking get in the way of enjoying life. Second guessing past decisions assumes that you fully understand the cause and effect relationship of the circumstance, and there's really no way that you can. You might as well just stop watching all cartoons.