[DSRP Evidence](https://dsrpevidence.org/)

# R9. Action and reaction are co-defined within a relationship

On Relationships

Must every action have an equal, opposite, and simultaneous reaction?

## Short answer

No. A relationship consists of an action and a reaction co-defined by the affect/effect relationship. The calculus requires an affect and an effect, but it says nothing by itself about equality, opposition, simultaneity, location, or linearity.

## Complete explanation

In the relationship pattern, action affects and reaction effects. The effect may be unequal in magnitude, delayed in time, distributed across several parts, indirect, nonlinear, amplified, dampened, or expressed elsewhere in the system. Newton’s third law describes a specific physical class of interactions. DSRP states the more general structural requirement that affects have effects. Apparent missing reactions therefore generate a prediction: the effect should be found in the field, another part, another time, or another level of organization. A violation would require an affect with no effect at all.

## Why the apparent counterexample arises

The apparent difficulty arises because “action–reaction” is read as shorthand for Newtonian equality, opposition, and simultaneity, importing conditions the DSRP calculus does not assert.

## Cases this settles

- [Abraham-Minkowski apportionment](https://dsrpevidence.org/case/7)

[All cases and resolutions](https://dsrpevidence.org/counterexamples)