What is the difference between something "existent" and something "necessarily existent"?

This is a fundamental question in philosophy, and understanding it helps in comprehending many philosophical proofs for the existence of God. The difference between "existent" and "necessarily existent" is the difference between something that can exist or not exist, and something that cannot but exist.

Simple Illustrative Examples

You exist now, but you could have not existed if your parents had not married. The Earth exists, but it could have not existed if the conditions of solar system formation had been different. Even the universe itself — according to many philosophers — could have not existed. All these things are "contingently existent": they actually exist, but their existence is not necessary.

"Necessarily existent" is completely different. It is an existent whose non-existence cannot be conceived. Its existence is necessary like the necessity that 2+2=4. It does not depend on anything else to exist, but rather exists by its very nature.

Inadequate Responses to Avoid

From some believers: "Necessarily existent is obvious, it's God, end of discussion." This is hasty. The philosophical concept of necessary existence needs explanation and justification. Jumping directly to "God" without clarifying the concept weakens the argument.

From some atheists: "Nothing is necessarily existent, everything is contingent." This is a strong claim that needs justification. If everything is contingent (can fail to exist), then why does anything exist at all? This raises Leibniz's famous question: "Why is there something rather than nothing?"

"The universe itself is necessarily existent." This needs evidence. Most physicists see that the universe could have been different (different physical constants, different laws). If it could have been different, then it is not necessarily existent.

Precise Philosophical Distinction

Contingently existent: What needs an external cause to exist. Its existence is not from itself. Its non-existence can be conceived without contradiction. Examples: humans, planets, galaxies.

Necessarily existent: What does not need an external cause. Its existence is from itself. Its non-existence cannot be conceived without falling into contradiction. According to theistic philosophers: God alone is necessarily existent.

Impossibly existent: What cannot exist because its concept is contradictory. Examples: a square circle, or a number that is both even and odd simultaneously.

Why This Distinction Matters

If everything in the universe is contingently existent (needs a cause), then there must be something necessarily existent to explain the chain of causes. Otherwise we fall into either an infinite regress of causes, or logical circularity (something causing itself).

This is the essence of the "argument from contingency and necessity" (or the cosmological argument from contingency): contingent things need a necessarily existent being to explain their existence.

Objections and Responses

Objection: "Perhaps the universe is an infinite series of contingent things."
Response: Even if the series were infinite, they all remain contingent and need explanation. An infinite series of train cars does not move without an engine.

Objection: "Concepts are merely linguistic games."
Response: The distinction between necessary and contingent is not merely linguistic. We use it in science and mathematics daily. Laws of logic are necessary, experimental results are contingent.

Where We Stand in This Discussion Today

Contemporary analytic philosophy has restored consideration to these concepts. Philosophers like Alvin Plantinga and Robert Koons have developed modern formulations of the argument from contingency and necessity. Even non-believing philosophers acknowledge the importance of the distinction between necessary and contingent in metaphysics.

The cumulative approach places this argument as part of a larger picture: if there is a necessary existent, and this necessary being is the source of order in the universe (cosmic approach) and consciousness (human approach), then a cumulative picture emerges that favors the theistic position.

For Advanced Reading

─ Intermediate level: Ibn Sīnā's argument from necessity and contingency
─ Advanced level: Plantinga's modern logical formulation of the ontological argument
─ "Contingency Argument" entry in Stanford Encyclopedia of Philosophy