If you notice a fact about the world, you can put it in one of two categories: necessary or contingent. A necessary fact is one that has to be the case, whereas contingent facts could have been different. Contingency means the outcome was the result of events that might have occurred differently, whereas necessity means the outcome could only ever have gone one way.
So you can think of it as a sliding scale:
- Necessary: must happen, cannot not happen
- Contingent: could happen or not, possible
- Impossible: cannot happen, could not have happened
If you really dig into necessity vs. contingency, you’ll see that it’s actually pretty controversial whether any particular fact fits into one category or the other – you could always make the case that something is necessary or that it’s contingent, so these lists are not set in stone (that is, they’re contingent!) However, the important thing is the difference between the two categories, not how you categorize any particular fact.
This concept is also made more complicated by the fact that it slides easily into thorny questions about fate, free will, choice, and the existence and nature of god. If, for example, you’re an absolute determinist, then you believe that there aren’t any contingent facts about the world, and everything is necessary! That means no one can decide to change what happens, which arguably means there’s no free will.
These questions are clearly important for philosophy, but for now, let’s focus on what the words “necessary” and “contingent” actually mean, without getting too far into metaphysical questions about fate and free will.
II. Contingency vs. Unpredictability
Contingency is closely related to unpredictability. Contingent events are usually unpredictable, because we can’t be certain whether a contingent event will turn out one way or another. For the most part, future events are both contingent and unpredictable.
As a result, some people use the words interchangeably – as though “contingency” just has exactly the same meaning as “unpredictability. But contingency and unpredictability are actually not the same thing. Unpredictability means that there may be a specific cause to a situation, but it cannot be figured out in practice. Contingency is not about the specific cause, it’s a fact about the situation and why it’s the case.
The sun will rise tomorrow.
This is a contingent fact about the world. It happens that our solar system functions this way, but the solar system could have formed differently, or not at all. Or a cosmic disaster could have destroyed the sun a million years ago, or could do so tomorrow. None of these things happened, but they could have, which makes this a contingent fact.
It’s predictable, though, because this is an event that will almost certainly come to pass. Like most predictions about the future, there’s some contingency involved here, but the sunrise is still predictable.
This is a necessary fact about the world. There’s no way that π could have equaled any other number. It has to be this way.
It’s also predictable – thanks to geometry, we know what π equals, and we know for sure that it will have the same value tomorrow, and the day after, and a billion years from now. It is a fundamental reality of our universe.
What will the weather be like in New York on April 19th, 2437?
This is clearly impossible to predict. There are way too many variables for anyone to know the answer. And it’s also contingent – there are all sorts of things that could happen in between now and then that would affect the outcome, such as how the climate changes and what, if anything, we decide to do about it.
(assuming some kind of determinism) On what date will you die?
For a variety of philosophical reasons, some people, both professional philosophers and ordinary folks, believe that there is a definite date, already set in stone, for each person’s life to end. But nearly all of them agree that there’s no way for any of us to know what that date is. Thus, there’s a necessary answer to this question (it’s not contingent, can’t be changed, and couldn’t have been different), but it’s still unpredictable.
III. Quotes About Contingency
“[What we need is] a metaphysics of morals, which must be carefully cleansed of everything empirical in order to know how much pure reason could achieve.” (Immanuel Kant, Groundwork for the Metaphysics of Morals)
Immanuel Kant famously tried to root his entire moral philosophy in necessity. He uses the “reason” to mean “necessary” and “empirical” for “contingent,” but the meaning is the same. In developing his positions on ethics, Kant didn’t want to base anything on contingent facts about the world – he wanted moral truth to be absolutely necessary rather than being derived from any facts about human beings or our world. He thought that an entire moral system could be derived, like geometry, from abstract logic itself. Since then, for over two hundred years, philosophers have been arguing about whether or not this kind of approach can ever be successful.
“Physicists often quote from T. H. White’s epic novel The Once and Future King, where a society of ants declares, ‘Everything not forbidden is compulsory.’” (Michio Kaku, Parallel Worlds)
This quote expresses a common view among physicists, who often see the world in terms of absolute necessity combined with deep unpredictability. That is, many physicists believe that whatever happens in the world is entirely caused by what has happened before – free will, if it exists at all, can only be a vehicle for these forces, it can never oppose or change them (see §5 and the idea of a self-fulfilling prophecy). Thus, every event is either necessary (“compulsory”) or it’s impossible (“forbidden”). On this view, there’s no such thing as contingency! But at the same time, it’s nearly impossible for any human being to understand these universal forces, which means these events are still unpredictable even though they’re necessary.
IV. The History and Importance of Contingency
The idea of necessity/contingency is a very old one in philosophy. That’s easy to understand when you realize the importance of this concept for human life: without it, how would we know the difference between what we can change and what we can’t? As human beings we have to choose when to accept something as inevitable, and when to spend our energy and time trying to change it. Contingency vs. necessity may have been an early way of figuring out what we could change and what we needed to accept.
Interestingly, the idea of “contingency” was mainly used in academic circles until the middle of the 20th century. After that, the word entered popular usage and today we talk about “contingency plans” and “contingency funds,” which are hedges against the contingency and unpredictability of the world. It’s possible that this is a response to a broader historical trend that crosses all fields – away from the sense of permanence, necessity, and solidity that was so widespread in the prior few centuries, and toward a sense of contingency, randomness, and unpredictability.
This affects not only philosophy and popular culture, but also art and science. Think, for example, of the discovery of “Heisenberg uncertainty” in quantum physics, which appears to show that basic aspects of matter, energy, and motion are contingent rather than necessary. This is a fundamental revolution in our understanding of the world, since for centuries physicists thought of such forces as purely necessary and deterministic. This new science has started to undo the attitudes described in the Michio Kaku quote above.
V. Contingency in Popular Culture
Example 1[SPOILER] Like many stories that deal with fate and choice, the Star Wars prequels play with contingency and necessity. In Revenge of the Sith, Anakin Skywalker begins having premonitions about the death of his wife, Padmé. Desperate to prevent this outcome, Anakin turns to the Dark Side to try and prevent this fate, demonstrating that he sees it as a contingent outcome, something he can change. In the end, though, Anakin’s decision proves fatal for Padmé – Anakin’s premonitions were a self-fulfilling prophecy. This prompts the question of whether her fate was really contingent or whether it was a necessary outcome, already written into the fabric of the universe and impossible to change.
Example 2[SPOILER] The movie Interstellar gets going when the young Murphy becomes convinced that some powerful beings are communicating with her through patterns in the dust blowing through her bedroom window. Initially, we are led to believe that these beings will turn out to be aliens or gods. However, Murphy fails to convince her father that this is happening, and he leaves on a doomed mission to interstellar space. After being sucked into a black hole, he enters the 5th dimension and is suddenly able to peer back in time to his daughter’s bedroom at the moment he decided to leave on his mission. In an effort to get Murphy to convince him not to leave, he traces patterns in the dust – exactly the ones that Murphy saw at the beginning. One interpretation of the ending is that what seemed like a contingent outcome is revealed to be necessary and determined by fate.