Conventional framing

Scientific explanation is often described using spatial metaphors such as “top-down,” “bottom-up,” “higher,” or “lower.” These expressions suggest that explanation proceeds along a hierarchy, with more fundamental explanations located at smaller or more basic levels of organisation.

In this framing, explanation directed toward components is typically treated as more fundamental, while explanation in terms of larger systems or contexts is treated as derivative or secondary.

APS reframing

In APS, these spatial metaphors are understood as expressions of explanatory direction rather than features of the world itself.

Explanation can be oriented in at least two complementary ways:

  • Analytic direction: explaining a system in terms of its constituent parts and their interactions.
  • Synthetic direction: explaining components in terms of the organised system within which they function.

These are not ontologically distinct “levels” of reality, but different orientations of explanatory practice applied to the same organised system.

APS rejects the assumption that one direction is intrinsically more fundamental than the other. Components only have biological significance within organised systems, while those systems exist only through the ongoing activity of their components.

Clarification

The language of “direction” is metaphorical. It does not describe movement through space or a hierarchy of reality, but the orientation of explanation relative to an organised system.

Describing explanation as “bottom-up” or “top-down” can therefore be misleading if taken literally. Such terms reflect shifts in explanatory perspective rather than distinct causal processes or ontological domains.

Role in APS

Explanatory direction clarifies how reductionist interpretations arise. When analytic direction is privileged, explanation is treated as proceeding primarily toward smaller components, and these components are taken to be explanatorily primary.

APS restores symmetry by recognising both analytic and synthetic orientations as necessary. Adequate biological explanation requires understanding how components contribute to the organisation of the system, and how that organisation constrains and enables their activity.

In this way, explanatory direction is not a feature of biological systems themselves, but a feature of how those systems are made intelligible through explanation.