The subject’s *system of taxa* consists of a taxonomy which allows the subject to evaluate and to classify the elements of the reference class, according to the criterion corresponding to a given duality A/Ā. These taxa can be considered as “what can see” the subject. It consists of a system of values that is inherent to the patient or of a filter through which the subject “sees” the elements of the reference class, i.e. the phenomena or the objects of reality.

The above figure represents an optimal system of taxa. The latter t is composed of 11 spheres which represent each a given taxon. The system of taxa is optimal, because all taxa are present.

It is worth noting that if the subject does not have some taxa, he cannot see nor count the corresponding elements. For example, if he/she lacks the taxa of the duality A/Ā corresponding to pole A, he cannot see the corresponding elements. In the same way, if the subject has no neutral taxon in his/her system of taxa, he cannot see the neutral elements of the reference class. More formally, let us consider then a series of* n* elements E_{1}, E_{2}, …, E_{n} such that each of them has, in a objective way, a degree *d*[E_{i}] in a duality A/Ā comprised between -1 and 1 (*d* ∈ [-1, +1]). We can consider then a series including 11 elements, E_{1}, E_{2}, …, E_{11}, which present an objective increasing degree (the choice of 11 elements is here arbitrary, and any other number would also do the job).

Franceschi P., Compléments pour une théorie des distorsions cognitives (in english), Journal de Thérapie Comportementale et Cognitive, 2007, 17, 2, 84-88.

Ambiguous images ** ▣** Arbitrary focus

**Bistable perception**

**▣****Complementarity relationship**

**▣****Conflict resolution**

**▣****▣**Conflict resolution with matrices of concepts

**▣**Conflict types relating to matrices of concepts

**▣**Contrary relationship

**▣**Courage

**▣**Dialectical contextualism

**▣**Dialectical monism

**▣**Dialectical monism in Aztec philosophy

**▣**Dialectical monism in Heraclitus

**▣**Dichotomic analysis

**▣**Dichotomic analysis applied to paradox resolution

**▣**Dichotomous reasoning

**▣**Disqualification of one pole

**▣**Disqualification of the positive

**▣**Doctrine of the mean

**▣**Doomsday argument

**▣**Dualities

**▣**Dual poles

**▣**Extreme opposition

**▣**General cognitive distortions

**▣**Instance of one-sidedness bias

**▣**Liar paradox

**▣**Matrix of concepts

**▣**Maximization

**▣**Mental filter

**▣**Minimization

**▣**Bistable cognition

**▣**Omission of the neutral

**▣**One-sidedness bias

**▣**One-sided viewpoint

**▣**Opposition relationship

**▣**Principle of dialectical indifference

**▣**Requalification into the other pole

**▣**Reference class

**▣**Reference class problem

**▣**Reference class problem in philosophical paradoxes

**▣**Reference class problem in the Doomsday argument

**▣**Reference class problem in Hempel’s paradox

**▣**Reference class problem in the surprise examination paradox

**▣**Selective abstraction

**▣**Sorites paradox

**▣**Specific cognitive distortions

**▣**Surprise examination paradox

**▣**System of taxa

**▣**Two-sided viewpoint

**▣**Viewpoint of a duality

**▣**Viewpoint of a pole