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# Fiat and Bona Fide Boundaries

## Details

**Authors** Smith, Barry and Varzi, Achille C.

**Year** 2000

**Publisher** Philosophy and Phenomenological Research

**Kind of work** article

**Discipline** Philosophy

**Secondary disciplines** Geography, Cognitive Science

**Applied** false

[Read it at the publisher](https://doi.org/10.2307/2653492) 
10.2307/2653492

## In authors' words

### What they set out to do (purpose)

To distinguish two kinds of boundary, those corresponding to physical discontinuities and those drawn by human demarcation, and to show the role of boundaries in an ontology of spatially extended objects.

### Who or what was studied (sample)

Not applicable (theoretical paper). Examples include the equator, the North Sea, national borders, and divisions of the femur.

### How they did it (methods)

Philosophical analysis with mereological and mereotopological formalization of boundaries, parts, wholes, contact, and dependence.

### What they found (results)

The authors argue that the distinction between bona fide boundaries (physical discontinuities) and fiat boundaries (human demarcations) is absolute, and that fiat boundaries are always parts of the entities they bound and cannot exist apart from them. Bona fide boundaries follow ordinary topology, while fiat boundaries require a different account, since two fiat boundaries can coincide. The authors conclude that boundaries must play a central role in a realist, non-reductionist ontology.

## Commentary

### In short

This paper separates boundaries that mark real physical breaks from boundaries people draw, such as borders and the equator. It shows how each kind relates to the things it bounds.

### Response

The paper is built on the distinction structure: what counts as an object depends on where a boundary is drawn, and the authors classify boundaries by whether they track a physical discontinuity or a human act of demarcation. The systems structure enters through the formal treatment of parts and wholes, in which fiat objects are carved out of larger wholes and higher-order objects are built from the boundaries of lower-order ones. The paper also states that language and perception impose fiat boundaries, which touches the perspective structure, but this is a secondary point and is not developed as a claim about differing observers. The work is philosophical and formal, so it speaks to the theory rather than providing empirical data.

**Patterns it shows** D, S

Formal proof or model

**Added** 2026-10-13

**How to cite this** Smith, Barry and Varzi, Achille C. (2000). Fiat and Bona Fide Boundaries. Philosophy and Phenomenological Research.