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The Swiss Cheese Model

There's this concept in risk analysis called "the Swiss cheese model" that explains accidents happen when a series of events line up perfectly, like the holes in this series of Swiss cheese slices--

When each of these conditions is met, when each of these chance occurrences happen, we have a specific event. One lecturer, David Heymann, used this same concept to describe an infectious disease event or outbreak. When a variety of specific conditions exist, they give way to an infectious disease emerging or spreading. This is to say that very specific "chance occurrences" must all happen for the result (which in this case is not necessarily a positive result) to come to fruition. And what are the chances of that? (I'm sure there's an epidemiologist or statistician out there itching to give me the very technical response).

This idea of fate and chance and coincidence and prediction intrigues me. I walked by the Wellcome Trust's building the other day and every window along the block displayed a different panel of their new Infectious Pattern campaign. This work is about understanding the patterns in disease outbreaks so that we may be better equipped to respond (and prevent them) in the future. One panel is even so ambitious as to proclaim a world without infectious diseases--the plausibility of this opens up a whole other can of worms and I feel ignores a great deal of what I mentioned in my last post about the fact that we do not inhabit this planet alone and there are many other living organisms whose very existence and interactions could hinder the realization of such idealism...but their optimism is still appreciated. While we may be able to identify and predict human behavior, I think there is a certain element of fate and chance that we cannot foretell when it comes to the mutation of viruses or the migration of their vectors.

These thoughts about disease outbreak prediction have juxtaposed well with my own life and some non-disease reading I have been enjoying in the form of Milan Kundera's The Unbearable Lightness of Being. Just a few pages into this book, one character concludes "That the love story of his life exemplified not Es muss sein! (It must be so), but rather Es konnte auch anders sein (It could just as well be otherwise)." Throughout the novel, Kundera challenges Friedrich Neitzsche's concept of "eternal recurrence"--an idea that the universe and its events have already occurred and will continue to recur infinitely. And if this is so, if every action we take and every move we make is just a piece of a predetermined puzzle, then where do we find meaning? If we are just one step, one factor, in a patterned sequence, is there meaning?

What's interesting is that, even with its heavy (or "light"...get it?) philosophical underpinnings, of whether or not life is unique and occurs only once (the opposite of Neitzsche's conjecture), Kundera's story is also employing the Swiss cheese model. At its core, the story of this novel portrays love--this strong and significant power humans ascribe--as a string of coincidences. A series of events that just happen to line up perfectly. Like the holes in a series of Swiss cheese slices. Giving way to a specific and distinctive end result.

It could just as well be otherwise. That the most powerful feeling in the universe or the most destructive infectious disease or the most insignificant meet cute could be staved off or catalyzed by just one factor is awesome in the truest sense of the word. So many events happen on this conditional probability of the event preceding it. If you hadn't stopped for that morning coffee, you wouldn't have missed your bus, you wouldn't have walked the long way to class, and you wouldn't have found the most beautiful park. Or if you hadn't taken the stairs in the tube station, you wouldn't have missed the train, and you wouldn't have run into your colleague in a city of millions (where you know approximately .00034% of the population).

I'm torn between feeling these series of coincidences are just that, coincidences themselves, or the definition of fate. Either way, neither of these--coincidence nor fate--lend themselves well to measurement and predictability. But if we believe that history repeats itself, then maybe the idea of being two steps ahead of disease outbreaks isn't so farfetched after all. If we can combine both Neitzsche's and Kundera's opinions on existence--the repetition but also the uniqueness and value of each life--then maybe we end up in a place where every action and project is valued not because it happened, but because it could just as well have not.

These moments are some of my favorite pieces of Swiss cheese in my life in London right now.


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