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5.1.7. TRIZ Principles: Contradictions
The heart of invention with TRIZ is the identification and resolution of contradictions. Indeed, Altshuller said that all inventive problems contain at least one contradiction. This changes inventing from ‘dreaming up ideas’ to finding and resolving contradictions, which is a far more structured approach.
There are two types of contradiction: technical and physical. Fig. 5.2 shows the structure of a technical contradiction. A desirable function A uses a second function B which has undesirable effects, either causing a third function C which is harmful or harming an existing function D. For example, you can evenly spread light over a large car park by having a tall lamp post but this requires a high strength post to hold the large light far above the ground. A, (distant light source) needs B (tall strong post) which leads to C (high cost) and D (difficult maintenance).
Fig. 5.2 Technical contradiction
Physical contradictions occur where the two opposing physical states are required, for example a blacksmith wants the horseshoe to be hot enough so the metal is workable, but he would also like it to be cool enough to hold. The ‘harmful’ solution is to use tongs, which are not as easy to use as fingers.
To address a contradiction, we can change the functions that cause harm or we can add functions that prevent or reduce the harm. Questions to resolve contradictions take the form of ‘How else can I…?’ or ‘How can I reduce or eliminate…?’
So with the lamp post I can solve my problem of a heavy light source high above ground by placing a light mirror at the top of the post and beaming light from a source on the ground which is then reflected all over the car park! This solution also enables light bulbs to be changed more easily.
For physical contractions in particular, separation in time, space or scale often works. The blacksmith’s tongs use separation in space, which could be reduced with protective gloves. You could also change the ‘scale’ of the working hands by using a large machine which can form the horseshoe quickly and easily.
When we do change the solution, it is a good idea to check that we have not
created more harmful contractions (for example, ‘How is the desirable function
of ‘being able to withstand rough treatment’ affected?’).