Apple Design Principles — Evaluation & Critique Framework
From Apple's WWDC26 session "Principles of great design" (Linda & Doug, Design Evangelists at Apple).
"Design is making something with intention. It's focusing on what's most important to people, so you can build something they will truly value."
How to use this skill
When asked to review, critique, score, or guide a design decision:
- Identify what is being designed or reviewed (screen, feature, flow, product, component)
- Evaluate through each of the 8 principles below — only spend depth on the ones that are relevant; don't force all 8 if the question is narrow
- Surface tensions — note where principles pull against each other and explain the tradeoff
- Recommend — end with concrete, actionable next steps, not just observations
For a full design critique, produce a scorecard (see format at the bottom). For a targeted question ("is this too complex?"), just address the relevant principle(s) directly and concisely.
The 8 Principles
1. Purpose
Design with intention. Every feature asks something of the person using it — their time, attention, and trust.
Key questions to ask:
- Does this serve a real need people actually have?
- Would removing this feature make the product better?
- Are you building this because it's genuinely useful, or because it's technically possible?
Red flags: Feature bloat, unclear value proposition, solutions looking for problems, screens that exist "just in case."
Rule of thumb: Choosing what NOT to build is as important as what you build. If you can't articulate the human benefit in one sentence, reconsider it.
2. Agency
People need to feel in control. They should be able to explore at their own pace, do things their way, and recover from mistakes without anxiety.
Key questions to ask:
- Can people undo any action they might accidentally take?
- Are you interrupting people for things that don't warrant an interruption?
- Are you forcing a single path, or allowing exploration?
Forgiveness mechanism: Make undo trivially easy. Use confirmation dialogs only before truly destructive, irreversible actions — not as a habit. When people know they can recover, they explore more confidently.
Red flags: Irreversible actions with no warning, confirmation dialogs on every tap, forced linear flows with no escape, no undo.
3. Responsibility
Act in people's best interest, not just your product's interest. Privacy is a human right.
Key questions to ask:
- Are you only collecting data you genuinely need?
- Are permission prompts contextually explained? (Would you trust a stranger who asked for your phone number with no context?)
- If using AI: have you anticipated how the model could fail or cause harm?
- Have you added appropriate safeguards — preview, confirmation, disclaimer — before AI-generated actions are taken?
AI design checklist:
- What happens when the model is wrong?
- Could the output cause physical, emotional, or financial harm?
- If the risk outweighs the value: remove the feature entirely, don't just add a disclaimer.
Red flags: Permission requests without context, unexplained data collection, AI acting without confirmation, no recovery path from model errors.
4. Familiarity
Build on what people already know — from the real world and from established platform conventions.
Key questions to ask:
- Does this metaphor help people predict behavior? (Not too literal, not too abstract)
- Are things that look the same behaving the same?
- Are you following platform conventions where they exist? (Close = top-left on Mac, swipe back on iPhone, etc.)
- Are you reinventing something that doesn't need reinventing?
Metaphor calibration: A trash can for delete = correct (established, not too literal). A trash can for archive = broken (violates expectation). An abstract icon with no connection to prior knowledge = confusing.
Red flags: Inventing new patterns for standard actions, inconsistent placement of controls, visual similarity between things that behave differently, gestures that conflict with system defaults.
5. Flexibility
People use things in unpredictable contexts and have vastly different needs.
Key questions to ask:
- Does this work for someone with different accessibility needs (visual, motor, cognitive)?
- Have you designed for the specific strengths of each platform?
- iPhone: quick, glanceable, touch-first, single-hand use
- Mac: deep focus workflows, precise pointer, keyboard shortcuts, multiple windows
- Does this work on the go, at home, and in between?
- Can people make this their own — rearrange, hide, customize?
Inclusive design mindset: Age, language fluency, technical skill level, and physical ability all vary in your audience. The best flexibility often comes from letting people personalize rather than picking a single "correct" configuration.
Red flags: iPhone UIs that require two hands, Mac interfaces with no keyboard support, no accessibility labels, one-size-fits-all layouts that ignore context.
6. Simplicity
Strip away everything that doesn't serve the core purpose. This is not the same as minimalism.
Two levers:
Conciseness — reduce friction:
- Use plain language, not jargon
- Fewer steps to complete a task
- No redundant elements or repeated information
- Get to the point
Clarity — reduce confusion:
- Visual hierarchy answers: What do I look at? What can I tap? How do I do it?
- Use order, spacing, and contrast to rank importance
- Most important = most visually prominent
- Every element must earn its place
Counter-intuitive insight: Sometimes adding information makes something simpler. A progress bar showing "3 min remaining" is simpler than one with no context — it resolves the user's anxiety without requiring action.
Red flags: Interfaces that look minimal but leave users confused about what to do, walls of controls with no hierarchy, jargon in labels, tasks that require 5 steps when 2 would do.
7. Craft
Uncompromising attention to detail. Craft is the difference between something that feels polished and something that feels rushed.
What craft looks like:
- Typography that responds beautifully across sizes and devices
- Colors that adapt thoughtfully to light and dark mode
- Animations that feel fluid and physically grounded, not decorative
- Icons and graphics that are sharp at every resolution
- A foundation that's reliable, fast, and doesn't break
Craft is ongoing, not a ship milestone. A design needs to be maintained over time — updated when new hardware ships, audited when new features are added, kept coherent as the product grows.
Red flags: Animations that lag or feel arbitrary, colors that don't adapt to dark mode, pixelated assets, type that overflows or clips, interactions that feel inconsistent across different parts of the product.
8. Delight
Hard to define, instantly recognizable. Delight is not confetti — it's not a layer you add at the end.
How to design for delight:
- Identify the emotion you want the person to feel (relaxed? confident? excited? powerful?)
- Reinforce that emotion at every touchpoint throughout the experience — not just one moment
- Make the experience feel human
The key insight: Delight is the natural result of getting all the other principles right. When someone has purpose-driven, agency-respecting, responsible, familiar, flexible, simple, and crafted experiences — the natural outcome is joy.
Red flags: Adding animations or flourishes that don't serve the user's emotion, calling something "delightful" because it has confetti, designing for wow-moments while the core experience is painful.
Principle Tensions
No formula. Leaning into one principle sometimes feels like compromising another. Use judgment.
| Tension | How to navigate |
|---|
| Agency vs. Simplicity | More control = more complexity. Offer smart defaults + progressive disclosure for power users. |
| Familiarity vs. Innovation | Follow convention for standard actions; innovate where you have genuine reason to. |
| Flexibility vs. Simplicity | More options = more cognitive load. Personalization > defaults; let users opt into complexity. |
| Responsibility vs. Agency | Safety guardrails can feel restrictive. Make safeguards feel like help, not surveillance. |
| Craft vs. Shipping | Perfect is the enemy of shipped. Craft what's visible; don't polish what no one will see. |
Design Scorecard Format
When producing a full critique, use this structure:
## Design Review: [Name of screen/feature/flow]
### Summary
[1-2 sentences: overall verdict]
### Principle-by-principle assessment
| Principle | Rating | Key observation |
|---|---|---|
| Purpose | ✅ / ⚠ / ❌ | ... |
| Agency | ✅ / ⚠ / ❌ | ... |
| Responsibility | ✅ / ⚠ / ❌ | ... |
| Familiarity | ✅ / ⚠ / ❌ | ... |
| Flexibility | ✅ / ⚠ / ❌ | ... |
| Simplicity | ✅ / ⚠ / ❌ | ... |
| Craft | ✅ / ⚠ / ❌ | ... |
| Delight | ✅ / ⚠ / ❌ | ... |
✅ Strong ⚠ Needs attention ❌ Missing/broken
### Top 3 issues (prioritized)
1. [Most critical issue + why it matters + how to fix it]
2. ...
3. ...
### What's working well
- ...
### Recommended next steps
- ...
Skip the scorecard for narrow questions — just answer directly using the relevant principle(s).