Physical Contradiction (TRIZ)

Overview

A **physical contradiction** exists when one and the same parameter of a system must take two opposite values at the same time. Unlike the technical contradiction of Altshuller's matrix ("if I improve A, B gets worse"), the physical contradiction is sharper — and that is its power: it forces the explicit statement "X must be A AND not-A".

Physical contradiction: A parameter X must take two mutually exclusive values at the same time. Formally: X should be A for effect 1 to occur. X should be ¬A for effect 2 to occur.

Classical examples:

• An aircraft wing must be **long** (for lift at take-off) and **short** (for low drag at cruise).
• A coffee cup must be **hot** (to keep the drink warm) and **cold** (so the lip doesn't burn).
• A welding electrode must be **thick** (for current capacity) and **thin** (to reach the joint).

Resolution is not via a matrix but via the **four separation principles**: time, space, condition, system level. One of these four principles resolves almost every physical contradiction — the question is just which one.

Approach

• Name the parameter clearly — *one* measurable attribute of the system, not the system itself ("wing length", not "wing").
• Phrase the two opposite requirements ("should be A, in order to …" / "should be ¬A, in order to …"). Crucially, capture the *in order to* — the function or effect each value serves.
• Sanity check: is this really a *physical* contradiction (one parameter, two values) and not a *technical* one (two parameters)? When in doubt, fall back to the contradiction matrix.
• Walk through the four separation principles one by one. For each, ask whether it applies to your case and write down the candidate idea.
• Pick the principle that fits and elaborate the concrete solution in the solution field — what changes when / where / under which condition / at which level?

If several principles apply, you may combine them — that is often the most productive solution. In that case pick the *dominant* principle and describe the combination in the solution field.

The four separation principles

1. Separation in time: The parameter is A at moment t₁ and ¬A at moment t₂. Example: a folding wing — short at cruise, long at take-off. Also: retractable landing gear, airbags that deploy only on impact, saw teeth that remove material on the cutting stroke and not on the return.

2. Separation in space: The parameter is A in region X and ¬A in region Y of the system. Example: a screw with a hard head (for the screwdriver) and an elastic shaft (against breakage). Also: a drill bit sharp at the tip and blunt at the shank; progressive eyeglass lenses.

3. Separation on condition: The parameter is A under condition C₁ and ¬A under condition C₂. Condition may be load, temperature, user, speed, … Example: a non-Newtonian fluid — liquid under low load, solid under impact. Also: photochromic eyeglasses, memory foam, ABS brake pressure responding to wheel slip.

4. Separation between system levels: The contradiction dissolves when you change hierarchy level: what is contradictory at the system level may resolve by splitting into subsystems (each subsystem taking just one of the values) or by embedding into a supersystem. Example: a bicycle chain — flexible as a whole, rigid in each link. Also: stranded wire (each thread thin, the strand thick), sandwich composites.

Relation to other TRIZ tools

The physical contradiction sits between the **contradiction matrix** (technical contradiction) and **Substance-Field analysis** (76 standard solutions):

• When the contradiction matrix returns *several conflicting* principles for a parameter pair or *no entry at all*, that is a hint: the core problem is probably a physical contradiction — switch here.
• The **9-Windows tool** sits upstream: it broadens the system view. Within one of the nine cells a concrete contradiction often emerges that this module resolves.
• The "system level" separation principle is directly related to the 9-Windows hierarchy axis — sub / system / super are the same levels.

References & further reading

• G. S. Altshuller: "Creativity as an Exact Science" (1984).
• D. Mann: "Hands-On Systematic Innovation" — chapter on physical contradictions and separation principles.
• V. Souchkov: "TRIZ Body of Knowledge" — short definitions of the separation principles.
• oxfordcreativity.co.uk — open examples for each separation principle.

Examples

This module ships with the following example datasets — load any of them in the app with a single click.

Available in the following cycles

• No fixed phase in cycle DMAIC (lives in the "More" tile).
• No fixed phase in cycle DMADV (lives in the "More" tile).
• 8D: D5 — Corrective Actions