Here's a true tale about my life that does a pretty good job of illustrating the philosophical notion of "contingency." I related it in a comment on my 2006 post, "Breaking free of family influences."
I graduated with a useless BA in psychology and was contemplating applying for an appropriately menial job. Then I overheard a conversation in the San Jose State cafeteria.
"Man, I can't do anything with a psych degree. And it takes at least three years to get a Ph.D." His friend replied, "You should get a M.S.W. It's just two years, and there are good jobs available after you graduate."
I had no idea what a M.S.W. was. I went to the library and looked it up. Everyone was talking about beautiful green Oregon, so I applied to the only school of social work in the state. Was admitted. Thirty-six years later, I'm still here.
A brief overheard conversation. My life heads off in a new direction. Go figure. I sure can't.
Seemingly, if I hadn't been in a certain spot in the San Jose State cafeteria at a specific time, in just the right location to overhear this conversation, I never would have applied to the Portland State University School of Social Work, never graduated with a M.S.W. and gotten a job at the Oregon Health Sciences University as a research associate, never moved to Salem to work for the State Health Planning and Development Agency, never met my second wife through her personals ad in Willamette Week, and, in general, never had the life I've lived here in Oregon since 1971.
That's contingency. Which is opposed to necessity. Here's a one-minute video that explains the difference between them.
Now, in my true-believing days -- when I accepted the notion of karma, basically an Eastern version of "God's will" -- I considered overhearing the cafeteria conversation as part of my destiny. A non-theistic person might say, It was the universe sending you a message.
Either way, there's a strong sense of necessity in these points of view. I was meant to go to graduate school in Oregon, where I'd settle down and have all sorts of Oregon'ish experiences, which are continuing as I type these words in rural south Salem.
But I don't see the conversation that way anymore.
Understand: I do still believe in determinism. Meaning, things happen for a reason. More accurately, reasons. Lots of them. Countless, in fact. So many reasons, of such astounding complexity, in most human circumstances it is impossible to fathom why this happened rather than that.
There were reasons why I was in a certain place in the San Jose State cafeteria at a certain time. There were reasons why the people I overheard talking had the conversation that they did. There were reasons why I was instantly attracted to the idea of getting a M.S.W. at an Oregon college.
However, it is easy to envision how, if those deterministic influences had been just slightly altered, my life would have taken a very different direction. There was no force of fate guiding my life, no God in control of my destiny.
There is just the brute fact of what happened: I overheard a cafeteria conversation that led me to move to Oregon. And the rest, as they say, is history.
I don't find this at all disturbing.
Yes, I used to enjoy believing that a higher power had my life (and afterlife) all mapped out for me in a loving, caring way. I was being taken care of. All I needed to do was go with the spiritual flow of my chosen religious belief system. Now, though, I'm unable to accept what I used to embrace on the basis of faith. My eyes have been opened to the contingency and facticity of reality.
Having dived deeply into existentialism in my early college years, I bought Sarah Bakewell's book, "At the Existentialist Cafe: Freedom, Being, and Apricot Cocktails." It's both a history and overview of 20th century existentialism. Here's some mentions of how Sartre viewed contingency in his writings.
Sartre's narrator is overwhelmed by nausea -- but with it comes an insight: that nothing in the world happens with any necessity. Everything is "contingent," and it could all have happened a different way. The revelation horrifies him.
...Eventually, while looking at the "boiled leather" of a chestnut tree in the local park and feeling the nausea again, Roquentin realises that it is not just the tree but the Being of the tree that is bothering him. It is the way in which, inexplicably and pointlessly, it simply sits there refusing to make sense or tone itself down. This is what contingency is: the random, outrageous thisness of things.
...Viscosity is Sartre's way of expressing the horror of contingency. It evokes what he called "facticity," meaning everything that drags us down into situations and inhibits us from flying free.
Well, even when I was deep into Sartre (I read every page of "Being and Nothingness"!) I never felt nauseous or horrified that the world is simply what it is -- with no overarching god-given or fateful necessity lording over the could-have-been-otherwise nature of existence.
In a lecture on Sartre, Ron McClamrock clearly explains the notion of nausea. I accept that Sartre felt this. I just don't feel myself that it is a necessary or typical reaction to understanding that the world is contingent. So what if things could have happened other than how they did? I'm fine with the thisness of existence and don't find it at all outrageous.
One major theme of Sartre's existentialism is the nausea of confronting being. Nausea, for Sartre, is a kind of philosophical vertigo which comes from grasping the utter contingency of all existence.
To grasp this, one can begin by reflecting on the utter contingency of your being where you are now. Consider all the details which had to be just so simply in order for human beings to exist on this planet --- the expansion rate of the universe, the balance of chemicals on the Earth, the cosmic rays penetrating the atmosphere to cause exactly the right mutations in earlier organisms, and so on.
Consider in addition all those precise coincidences needed for your parents to be born, to meet, to have children. Add to this all those improbable circumstances necessary for your being born --- for say, exactly that sperm cell to fertilize exactly that egg, so that you and not one of your possible siblings were born. And, of course, pile on all the circumstances necessary for you to have come to where you are today, reading this --- the influences of parents, friends, and teachers; the circumstances of education, employment, and affection.
How likely is that all of those factors came together in exactly the way they did? It is so absolutely, utterly unlikely that we find ourselves perched on a pinnacle of utter improbability, of total contingency, and the height of improbability is dizzying.
There is absolutely no reason that there should have been such a ridiculous coincidence of events; but such a ridiculous coincidence is exactly what the existence of each of us rests upon. My own non-existence is so immensely much more likely than my existence that the foundation of my existence is left as a needle-thin tower of improbability. It is from this that the existential vertigo of nausea comes.
It's important to see that the point here really has very little to do with issues about determinism at, say, the physical level. Regardless of whether some kind of physical determinism is true about the world (or even about our actions), the sort of utter contingency which is important for Sartre still remains.
The critical point for the purposes of nausea or existential vertigo is that there is no reason why the real world is the real one rather than some other possible world being real. There may be causes (say, stated in some micro-physics) such that the state of the universe at the big bang determines my existence and position now. But that does not give a reason why I am here rather than not --- that is still, if you like, a kind of cosmic accident.
So it's not determinism that's at issue here, but a kind of fatalism.
There is no reason that I should have been born, even if it turn out that there is a physical causal story to tell about how the physical events which were my birth came to happen. There is no explanation for it as my birth. My birth was not destined, in that nothing was working to insure that I was born, even if the physical event of my birth was causally necessitated by the initial conditions of the universe and the blind laws of nature.
To twist around Leibniz, we might call this the "principle of insufficient reason": there is no reason for anything being the way it is (even if there are causes of it); this is not only not the best of all possible worlds, it is as unlikely as any, and thus utterly contingent.
Again, fine with me. I like the idea that I've living in an utterly unlikely world.