Necessary/contingent

Some philosophical distinctions have a whiff of the esoteric about them, but others closer to common sense. The distinction between the necessary and the contingent falls into the latter category. In essence, it is the distinction between those things that must be the way they are and those that could have been otherwise. But what sorts of things? It doesn’t take philosophers long to start making distinctions, so let’s consider an important one here.

Events and claims

Normally, in discussions of necessity and contingency philosophers distinguish between two types of necessary and contingent things.

Claims that are always true, in all cases, no matter what, are necessary claims. It is simply not possible for claims that are necessarily true to be false – and for those that are necessarily false to be true. Contingent statements, by contrast, are claims that happen to be true (or false) but could be false (or true); they are claims that under some conditions are true and under other conditions are false.

Necessary states of affairs are, by contrast, events or states of being that simply couldn’t be otherwise. If an event happens necessarily, it is impossible for it not to happen. If, on the other hand, an event is contingent, it is possible that it might either occur or not occur.

As an example of a necessary truth, consider any mathematical truth, say, 2 x 2 = 4. This is traditionally seen as a necessary truth, since, given the meanings of ‘2’, ‘4’, and ‘x’, it must always be true that 2 x 2 = 4. It could not be otherwise. (Of course, it is true that we could have used the symbols of ‘2’, ‘4’, and ‘x’ to stand for other things, but the necessity we ascribe in this case is not that those particular symbols stand for what they do, but that, given the meanings they have, 2 x 2 = 4 is necessarily true.)

If, however, you consider a historical truth like ‘George W. Bush was the president of the United States from 2001 to 2009’, it seems perfectly reasonable to say that this statement is not necessarily true and that there’s nothing necessary about the state of affairs it describes. Had a few things gone differently in Florida before, during and after the US presidential election of 2000, it would have been Al Gore who entered the White House as president, and it would just have been plain old Governor Bush. Because there is no necessity about it, the fact that ‘George W. Bush was the president of the United States from 2001 to 2004’ is a contingent truth.

Determinism, Spinoza and necessity

Conceptually, the distinction is therefore a clear one. As you can imagine, however, things become more controversial once you try to decide what actually is necessary and what actually is contingent. For example, if you are a strict determinist, then you believe that everything that happens is the inevitable consequence of what has gone before. There is no room for luck or free will. From this point of view, nothing is contingent, and all events are necessary. ‘George W. Bush was the president of the United States from 2001 to 2009’ would be a necessary truth, since as a determinist would see it this fact could not be otherwise. Though it looked to us as though the election could have gone either way, in a deterministic universe the result was inevitable. Along just these lines, the seventeenth-century philosopher Spinoza is famous for holding that everything happens necessarily, and hence all thoroughly true claims are necessary truths. Eighteenth-century philosopher Immanuel Kant tried to get around the problem by holding that from one point of view (that of human experience) everything that happens in the course of the world we inhabit occurs necessarily; while from another point of view (that of a metaphysical world beyond our experience) human actions are sometimes free and contingent. Other philosophers, sometimes called ‘compatibilists’, have held that properly understood human actions can be legitimately described as both necessary and free.

Quine and Contingency

At the other extreme, if you buy into W. V. O. Quine’s semantic holism, then everything becomes contingent. It is always the case that what we judge now to be true we might later judge to be false. Mathematical truths such as 2 x 2 = 4 appear to be necessarily true, but we can’t rule out the possibility that facts or reasons will emerge about the meanings of the terms involved that will lead us to revise our judgment.

So, although it is easy enough to define the difference between the necessary and contingent, it is much harder determining precisely which truth-claims belong under which category.

Example: the existence of God

The distinction crops up in many branches of philosophy, including arguments concerning the existence of God. Consider God as a hypothesis. If God exists, would God be a necessary or contingent being: it can’t be that God exists but might not have done so. If God exists, God must be a necessary being, and the claim that ‘God exists’ is a necessary truth. One way of conceiving God this way is to say that it is part of the concept of ‘God’ that God necessarily exists. What some philosophers have tried to argue is that this means God must in fact exist, since a non-existent God would be a contradiction in terms: a necessary being who doesn’t in fact exist. Saying that God does not exist would be as self-contradictory as saying that a triangle does not have three sides. This argument can be found in the work of rationalist philosophers like Descartes and Spinoza. It has its principal roots, however, in the Proslogion of Anselm of Canterbury  (c.1033-1109). Even some modern-day philosophers like Alvin Plantinga adhere to versions of it. A related theological issue is whether or not it was necessary that God created the world.

Problem: the future and the excluded middle

In section 9 of his text Interpretation Aristotle points out something interesting with regard to our talk about the future. Consider the statement ‘A sea battle will take place tomorrow’ (uttered by someone the night before the Battle of Salamis in 480 BCE). Most of us would say that the statement was on that evening either true or false. But here’s the rub: if that statement was either true or false before the battle occurred, then it seems that the future was (and is!) already necessary and determined. This seems an intolerable conclusion for many to draw. One way to preserve the contingency of the future, of course, is to hold that our claims about the future are neither true nor false until the events they predict actually occur, but such an option seems to many equally intolerable. Refusing to assert the truth or falsehood of statements about the future seems not only practically impossible (we wouldn’t be able to say that it is true that someone will keep a promise or be there at an appointment); it also seems to violate one of the fundamental principles of rationality – the law of excluded middle – which holds that a statement must be either true or false, but not some third alternative.

You can see that even though things looked pretty simple at the outset, there’s a lot going on with these concepts Although the distinction between the necessary and the contingent has its roots in common sense, you can be sure that in the hands of philosophers it becomes something much more extraordinary.

• Aristotle, On Interpretation Ch. 9 (fourth century BCE)

• Alvin Plantinga, The Nature of Necessity (

• Saul Kripke, Naming and Necessity (1980)

Aristotle, Alvin Plantinga, and Saul Kripke. “Chapter 4 Tools for Conceptual Distinctions: 4.12 Necessary/contingent.” Ed. Julian Baggini and Peter S. Fosl. The Philosopher’s Toolkit: A Compendium of Philosophical Concepts and Methods. 2nd ed. Oxford: Wiley-Blackwell, 2010. 170-73. Print.