From Luca Dellanna, *The Control Heuristic*, Ch 1.5:
When someone fails to perform a mental or physical task, there are exactly two possible root causes:
| Root cause | Description |
|------------|-------------|
| **Can't** | Missing know-how, skill, or capacity |
| **Won't** | Low EEO — brain doesn't want to |
We routinely misdiagnose, calling someone lazy when they lack knowledge, or prescribing more teaching when the problem is emotional. Wrong diagnosis produces wrong intervention and damages trust.
## The Diagnostic Test
Assume it's a know-how problem. Give an easier version of the same task.
| Result | Diagnosis |
|--------|-----------|
| Performance improves relative to difficulty | **Know-how problem** — they can do easier tasks; gap is specific knowledge |
| Performance unaffected by difficulty (still refuses or barely engages) | **Motivation/EEO problem** — difficulty is not the bottleneck |
**Example**: Student can't solve quadratic equations.
- Asks for linear equation → solves it easily → gap is quadratic-specific knowledge → teach quadratics
- Asks for linear equation → refuses or grudges through it → problem is emotional associations with math or homework → address EEO, not content
## Why It Matters
Offering knowledge to a motivation problem (or motivation to a knowledge problem) suppresses the symptom without addressing the root cause. Unaddressed root causes keep generating new problems — and in relationships, offering the wrong solution is actively trust-damaging.
## Related
- [[Mental Actions Are Gated]] — mental tasks have EEO requirements, not just skill requirements
- [[Expected Emotional Outcome]] — the actual bottleneck in motivation cases
- [[Procrastination as Gating Symptom]] — procrastination is the same won't-vs-can't misread at scale