Occam's Razor
Among competing solutions that meet the requirement, prefer the one with fewest assumptions and moving parts.
Definition
A principle of parsimony attributed to the fourteenth-century logician William of Ockham. Applied to design, it argues for the solution that satisfies the requirement with the least additional machinery, not the solution that is smallest.
Craft convention. True because the industry converged on it. Breaking it costs familiarity, not correctness.
On this plate
Reach for this when
- Reviewing a design that has accumulated elements over time.
- Choosing between two solutions that both meet the requirement.
- Auditing settings, fields and confirmations.
- Two designs both satisfy the requirement and one has more moving parts.
Common mistakes
- Removing capability rather than complexity.
- Confusing visual minimalism with structural simplicity.
- Applying the razor to the interface while the underlying model stays tangled.
Questions the razor asks
- 1.What is the actual requirement, stated without reference to a solution?
- 2.What is the smallest thing that meets it completely?
- 3.What does each additional element buy, and for whom?
- 4.What breaks if it is removed? If nothing, remove it.
- 5.Is the complexity load-bearing, or is it habit?
Applied to interfaces
The most common wins are removal of things that were never needed: a field nothing consumes, a confirmation for a reversible action, a setting with one sensible value, an animation that delays without informing.
The most common failures are removals that push complexity onto the user rather than out of the system. That is Tesler's Law, and the two principles have to be read together.
Cutting without amputating
Do
- Remove the element whose absence nobody would notice, and check that claim with data.
- Collapse two settings into one when nobody sets them independently.
- Prefer the design with fewer states to maintain, not the one with fewer pixels.
- Keep the simplification if it survives the edge cases.
Do not
- Remove a control because the screen looks busy, and leave the need unmet.
- Confuse visual sparseness with conceptual simplicity. A blank screen with hidden gestures is not simple.
- Cut the explanation along with the thing it explained.
In practice
- i.
Removing the confirm password field
SignupA show-password toggle plus a clear error on failed login achieves the same protection against typos with one field instead of two, and it works better for password managers.
- ii.
One setting instead of three
Application preferencesThree related toggles that are never set independently are one setting with a good default. Check the analytics before assuming users want the granularity.
- iii.
The setting that was two settings
Collapse, not deleteNotify me by email and notify me by push were always set together by ninety-four percent of accounts. One control with an advanced disclosure served everyone and halved the decision.
Commonly confused with
Close neighbours that get substituted for each other. The difference is stated first, then the condition that picks one over the other.
Tesler's Law
LawIrreducible complexity cannot be deleted, only shifted between user, interface and engineering.
Key difference
Occam's Razor says prefer the solution with fewest moving parts. Tesler's Law says a residue of complexity cannot be removed at all, only moved. One picks between designs; the other decides who carries what neither design can avoid.
Use Occam's Razor when
- Several designs would work and one is more elaborate.
- You are justifying cutting machinery rather than moving it.
- The complexity in question is genuinely avoidable.
Use Tesler's Law when
- Simplifying the screen has quietly pushed work onto the reader.
- The argument is about who absorbs the difficulty.
- Someone is proposing to remove something that has to live somewhere.
Local chart
PRIN·001 · Region I · Grid A1
This entry and the entries it is stated to connect with. Each line is labelled with what the connection means.
Sources
Where a source establishes something narrower than the popular reading of it, the note says so.
- [1]
Attributed to William of Ockham
Scholastic philosophy, fourteenth century
A principle of logic and explanation, later adopted into design practice. It has no experimental basis and is not a UX finding.
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Applies when you are designing
Applied through
Where this shows up as a concrete interface decision.
- WhitespaceFND·015 · UI foundation
Often used with
These usually appear in the same screen or the same decision.
- Design CritiqueTPL·012 · Template
Short definition
The one-paragraph version, for when that is all you need.
- Data MinimisationTERM·108 · Term
Related concept
Connected closely enough to change how you apply this.
- Aesthetic and Minimalist DesignHEUR·008 · Heuristic
- Hick's LawLAW·001 · Law
- Law of PrägnanzLAW·017 · Law
- Pareto PrinciplePRIN·002 · Principle
- Progressive DisclosurePRIN·003 · Principle