When I look at this question, and the word “reason,” I think that the thing that happens had an intended purpose. From my point of view, I would definitely say everything happens for a reason. After all, I am a Christian, and I believe that God makes everything, from the little interactions between particles to the big news stories, happen for a reason.
On the other hand, if I were arguing from a global point of view, the answer would be more complex. First off, I would immediately say that the unimportant things don’t happen for a reason; for example, tying your left shoe before your right. Does this really affect the rest of your life? The obvious answer would be no… or does it?
One of the books of my childhood that fascinated me was A Sound of Thunder by Ray Bradbury. The book basically suggests that any action that happens, whether it be you speaking to a friend or stepping on a butterfly, will affect the future timeline. For example, in the book, the main character (whose name I forgot) steps on a butterfly in the prehistoric era before going back to the present. Upon arriving in the present, he sees that Chicago has completely transformed, the English spoken is totally different, and it is run by a totalitarian regime.
I’ve always been fascinated by the idea that every action causes ripples whose magnitudes are amplified through space and time. That is, one action will lead to another action which will in turn lead to another action, cascading in a snowball-like effect which ultimately alters the future. Maybe if I typed this post faster North Korea may nuke us a day earlier. I’ve always felt like there are connections between the present and the future. On the other hand, my Christian faith tells me that God has planned out all the details of the future down to the picosecond. What you are doing now will not influence what God planned for the future.
But of course, the idea of altering history through stepping on a leaf is a very fascinating idea. I wonder what everyone else thinks about this?