Bunge on existence

Explain this theory by Mario Bunge:

Passage from Doing Science by Mario Bunge omitted.

Here’s Bunge’s picture of “what it means to exist,” in plain terms and without the symbolism getting in the way.

The big idea

Bunge is a realist: to exist in the real world is to be material and therefore capable of change. He carefully separates:

• What something is (an ontological definition) from
• How we find out that it exists (an epistemic criterion).

He then contrasts real existence with other, context-bound kinds of existence (phenomenal, conceptual, semiotic, and fantastic) and warns against mixing them up.

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1) Real existence (absolute, observer-independent)

Definition (what it is): To exist really = to be mutable (able to be in more than one state). If a thing can change, it’s real.

Another way to say the same: a real thing has a state space with at least two possible states (e.g., “here at t₁” vs. “there at t₂”).

Criterion (how we know): A thing is real if it makes a difference to at least one other real thing (or is affected by others). In short: causal power is the tell-tale sign of reality.

Key points:

• This kind of existence is absolute (not relative to minds, languages, or contexts).
• Example: gold is defined by atomic number 79 (what it is), and we can test it (how we know). The Higgs boson counts as real because it changes detectors in characteristic ways.

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2) Phenomenal existence (mind-relative)

What it is: To exist phenomenally is to occur in someone’s sensory experience.

How we know: There is at least one sentient subject who feels/perceives it.

Key points:

• Relative to subjects. Hallucinated “monsters” exist phenomenally for the sufferer, but lack real (material, causally efficacious) existence.
• Bunge’s jab: phenomenalists risk collapsing the real into the merely experienced.

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3) Conceptual existence (system-relative)

What it is: To exist conceptually is to be a member of a conceptual system (a network of constructs bound by rules: logics, algebras, theories).

How we know: By proof or definition within that system (e.g., √2 exists in the real-number system; Fermat’s Last Theorem says certain integer triples do not exist in number theory).

Key points:

• Relative to the system; proofs show satisfiability in a model, not physical presence.
• Debates like constructivism vs. classical math are internal to this realm (e.g., the Axiom of Choice). Bunge the “fictionist” about math: these objects are useful fictions—not material things—yet indispensable for science.

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4) Semiotic existence (sign-relative)

Two senses:

1. Pragmatic (existence by proxy): A sign (like a stop sign) exists semiotically for an animal if perceiving/evaluating it reliably triggers behavior.

   • Real because it enters causal chains via interpreters (drivers, organisms).

2. Denotational: A symbol is realistic if it denotes a real entity (e.g., the metric tensor denoting the gravitational field).

Key point: Signs are material marks that acquire meaning through trained interpreters; without interpreters, they’re mere shapes.

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5) Fantastic existence (fiction-relative)

What it is: An entity exists fantastically if it figures in a work of fiction (Caliban, dragons, superheroes).

Key points:

• Relative to the story and an audience capable of fantasy.
• Art and religion trade in this mode (Bunge is intentionally provocative here), while science mustn’t.

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Surrealism (Bunge’s warning label)

Bunge criticizes interpretations like many-worlds and multiverse as surreal: they posit realms that are, in principle, untestable, hence unscientific, and they violate parsimony. His standard remains: real = causally efficacious, empirically testable.

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The “existence is (sometimes) a predicate” move

Against the slogan “existence is not a predicate,” Bunge says: once you fix a universe of discourse (the context: real things, signs, numbers, fictions), you can meaningfully apply an existence predicate within that context. This formalizes the idea that different kinds of existence are contextual, except the real, which is absolute.

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Why this matters (the cheat-sheet)

• Don’t confuse real with experienced (phenomenal), defined/proved (conceptual), sign-mediated (semiotic), or imagined (fantastic).
• Test for the real: can it change (has multiple possible states) and enter causal relations?
• Test for the conceptual: is it derivable/definable in a formal system?
• Test for the semiotic: does it systematically guide behavior or denote something real?
• Test for the phenomenal: does someone experience it?
• Test for the fantastic: does it live in a fiction?

In short, Bunge offers a clean taxonomy: only real existence is mind-independent and binary; the others are useful but context-bound. Good science sticks to the real while using the conceptual and semiotic—and keeping fantasy in its lane.