What Does It Mean to Be Real?

Can the unseen be real?

Science explains observations using entities we cannot simply hold—electrons, fields, spacetime. Scientific realism says the success of mature theories gives reason to believe that they are at least approximately true about observable and unobservable parts of the world.

Antirealist positions hold that accurate prediction may be enough; we need not believe that every hidden entity posited by a theory literally exists.

• Stanford Encyclopedia of Philosophy, Scientific Realism

  A scholarly overview of the central realist and antirealist positions.

Successful theories still change

Realists explain striking scientific success by saying theories capture something about the world. Critics point to past theories that succeeded and were later abandoned.

The issue is how far we may travel from ‘this theory works’ to ‘the world truly resembles the theory’s picture.’

What if relations outlast objects?

Structural realism emphasizes mathematical relations or structures that survive theory change. We may not know the world’s ultimate ‘stuff,’ it suggests, while still gaining access to its relational structure.

Debate returns over whether structure can be real without saying what instantiates it, and how to identify the structure that has genuinely been preserved.

• Stanford Encyclopedia of Philosophy, Structural Realism

  A scholarly survey of forms of realism centered on structure retained across theory change.

Four layers of the reality question

It from Bit asks about observation and information; Landauer asks about physical implementation; the simulation argument asks about a possible external cause; realism asks how theories relate to the world.

The questions connect but are not the same claim. Exploring reality means tracking what each argument establishes and what it continues to assume.