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Model Construction

A 2D model of the ten sign classes
Peirce’s system of the sixty-six classes of sign is the further elaboration of his system of ten main classes of sign. Their foundation is the triadic phenomenological system and the triadic definition of the sign itself.

The phenomenological categories
Peirce’s three phenomenological categories of firstness, secondness, and thirdness, which he also called cenopythagorean categories, are the foundation of his semiotics (CP 8.328, 1904). According to one of their many definitions, “the First is that which has its being or peculiarity within itself. The Second is that which is what it is by force of something else. The Third is that which is as it is owing to other things between which it mediates” (W5: 229).


The category of Firstness is related to the ideas of mere quality, originality, novelty, chance, spontaneity, potentiality, and indetermination. Firstness is independent from any determination and without reference to anything else. Secondness is the category of dyadic relations, of experience and effort, opposition and conflict, resistance and brute action, of the actuality of the hic and nunc. Secondness manifests itself in the individual moment of a singular experience without permanence in time. Thirdness is the category of law, thought, habit, continuity, and mediation between a First and a Second. It is the mediating term that can connect any two things. Generality, purpose, and representation are concepts which cannot be conceived of without the category of thirdness. Hence, “the first thing one can say about a phenomenon is that it must be of some quality, the second that it has a specific mode of existence, the third, it is capable of having kinds of relations” (Müller 1994: 143). The three categories are interrelated as follows: firstness is independent of any other category; secondness depends on firstness; and thirdness depends on secondness and firstness.

The sign trichotomies

The concept of sign is so omnipresent in Peirce’s writings that some scholars consider semiotics as the center of Peirce’s whole philosophical edifice. Among his many definitions of the sign or “representamen” is the following: “A REPRESENTAMEN is a subject of a triadic relation TO a second, called its OBJECT, FOR a third, called its INTERPRETANT, this triadic relation being such that the REPRESENTAMEN determines its interpretant to stand in the same triadic relation to the same object for some interpretant” (CP 1.541, 1903).


Hence, the sign is a mediator between its object and its interpretant; it determines an interpretant which functions as a sign in a triadic relation of its own. The sign determines its interpretant which in its turn has its own potential of acting as a mediator in a theoretically infinite process of a semiosis.


Another definition of the sign is the following: “A sign, or representamen, is something which stands to somebody for something in some respect or capacity” (CP 2.228, 1897). In this definition, Peirce puts forward that the sign can never represents its object completely, but only partly, in relation to a certain idea. This incompleteness of the sign is the source of the never ending process of semiosis. One of the causes of this incompleteness is that there always remains the possibility of another sign representing the same object in a different way or relative to some other aspect. According to Short (2004: 10), with this account of semiosis, Peirce adds to the Kantian problem of knowledge the Aristotelian idea of continuum. Since his earliest writings on signs, instead of studying thought per se, Peirce had emphasized the notion of thought as a process and of knowledge as a movement. One of his earliest comments in this respect is: “At no instant in my state of mind is there cognition or representation, but in the relation of my states of mind at different instants there is” (W2: 227). Close to the end of his life, in a letter to Lady Welby of 1908, Peirce presented this much more detailed concept of sign:

“A sign, therefore, has a triadic relation to its Object and to its Interpretant. But it is necessary to distinguish the Immediate Object, or the Object as the Sign represents it, from the Dynamical object, or really efficient but not immediately present Object. It is likewise requisite to distinguish the Immediate Interpretant, i.e. the Interpretant represented or signified in the Sign, from the Dynamical interpretant, or effect actually produced on the mind by the Sign; and both of these from the Normal Interpretant, or effect that would be produced on the mind by the Sign after sufficient development of thought.” (CP 8.343, 1908)

This definition of the sign shows once again how the sign is the mediating factor between its object and its interpretant.


In his earlier classification of signs, Peirce considers only three trichotomies: the sign in itself, the sign in relation to its dynamical object, and the sign in relation to its final interpretant. Each of these trichotomies belongs to one of the three phenomenological categories. Hence, the sign itself is a qualisign when its ground is one of firstness; it is a sinsign when its ground is one of secondness; and it is a legisign when its ground is one of thirdness. Furthermore, in relation to its dynamical object, the sign can be an icon when this relation is one of firstness; it is an index when the relation is one of secondness; and it is a symbol when the relation is of thirdness. Finally, with regards to the relation between sign and its final interpretant, it is a rheme when this relation is one of firstness, a dicent when it is one of secondness; and an argument when it is one of thirdness.

Preliminary 2D model of the ten classes of signs

The first sketch in the elaboration of the 2D diagram for the ten classes of signs was a tree diagram with upward branches. The growth of a tree indeed evinces an affinity with sign processes, since each bifurcation of a branch results in a triadic structure. The temporal order in the sequence of the antecedent to the subsequent evinces another affinity between the growth of signs in semiosis and the growth of the branches of a tree. The antecedent belongs to the past, which is already determined; the subsequent pertains to the future, whose full of possibilities are still undetermined.

Inspired by the idea of the parallelism between the growth of trees and the growth of signs, the diagram adopted the diagrammatic image of tree rings used in dendrochronology to count the age of the trees by counting their annual growth rings and to derive insights into climate changes over the centuries from their size. More than signs of time, tree rings are indices of influences between ecological systems systems. The growth of tree rings has affinities with the process of semiosis. The first trichotomy lies in the center of all rings; the next trichotomy begins with the second ring, etc.


Peirce derived his ten main classes of signs from the logic of his cenopythagorean categories. Thus, if the first constituent of the trichotomy is of the nature of firstness, the phenomenologically simplest mode of being, it can only determine relations of this very category. If the first constituent of the trichotomy is an existent, which is of the nature of secondness, then it can determine as its second constituent of its trichotomy only a relation of mere possibility (firstness) or existence (secondness). Finally, if the ground of the sign is a law (thirdness), the relation between sign and its dynamical object can be one of a possibility (firstness), existence (secondness), or law (thirdness).



1. Rhematic Iconic Qualisign

2. Rhematic Iconic Sinsign

3. Rhematic Indexical Sinsign

4.Dicent Indexical Sinsign

5 Rhematic Iconic Legisign

6. Rhematic Indexical Legisign

7. Dicent Indexical Legisign

8. Rhematic Symbolic Legisign,

9. Dicent Symbolic Legisign;

10. Argument Symbolic Legisign.

From the ten classes to the ten trichotomies and the sixty-six classes
It is well known that Peirce expanded the system of sign relations first by introducing the additional subdivision of the object into the immediate and dynamical object and then by introducing the further subdivision of the interpretant into the immediate, the dynamical and the final one. The immediate object is the way in which the dynamical object is represented within the sign. The dynamical object is the object that is outside the sign and which the sign intends to represent. To represent it, the sign must determine an interpretant which also represents the object of the sign. That is possible because within the sign there is the immediate interpretant which has the power of determining an interpretant outside the sign, that is, the dynamical interpretant. This dynamical interpretant is an interpretant produced in an interpreting mind. A sign can determine more than one dynamical interpretant since all dynamical interpretants are potentially contained in the immediate interpretant. The final interpretant is the interpretative result to which every interpreter might come when the semiotic process is sufficiently developed (Short 1996: 493-94).


1st, According to the Mode of Apprehension of the Sign itself,
2nd, According to the Mode of Presentation of the Immediate Object,
3rd, According to the Mode of Being of the Dynamical Object,
4th, According to the Relation of the Sign to its Dynamical Object,
5th, According to the Mode of Presentation of the Immediate Interpretant,
6th, According to the Mode of Being of the Dynamical Interpretant,
7th, According to the Relation of the Sign to the Dynamical Interpretant,
8th, According to the Nature of the Normal Interpretant,
9th, According to the Relation of the Sign to the Normal Interpretant,
10th, According to the Triadic Relation of the Sign to its Dynamical Object and to its Normal Interpretant.

Like the three trichotomies introduced before these ten respects in which the classes of signs are determined allow a further subdivision according to Peirce’s three phenomenological categories. Firstness, secondness and thirdness constitute general classes which become particular when the are realized in the trichotomies. The Figure below give the names of the resulting trichotomies:


It is not the purpose of this paper to explain the further details of each trichotomic subdivision (but CP 8.342-375, 1908) although it was indispensable to present all of them as the foundation of the sixty-six classes of signs whose diagrammatic representation will be discussed in the following.

The system of the sixty-six classes obeys the same logical rules which determine the system of the ten classes of signs. As discussed before, each class is determined by the possibilities of triadic combinations and restrictions on the combination of the constituents. When three trichotomies are considered, the structure of each sign must be described in three stages; with ten trichotomies, each class must be described in ten stages. Since, according to the logic of the phenomenological categories, the nature of each previous stage determines the possibilities of constituting a sign in the next higher of the ten trichotomies and a number of combinations remain excluded, there are altogether sixty-six possible classes of signs.

Models of the sixty-six Classes of Signs

The diagram construction begins by the idea of tree rings. They are used in dendrocronology to count the age of trees. As years go by rings grow in trees, but they are also affected by climate factors. More than sign of time, tree rings show interaction between systems. All these concepts are welcome in semiotic process. Each ring corresponds to one trichotomy: the first trichotomy comes in the centre, the second trichotomy in the second ring and so on.

Since there is a determining relation among the rings, in order to start constructing the diagram of 66 classes of signs a better understanding of the order of the trichotomies was necessary. It was not easy to decide in which order the trichotomies should appear, since this is one of the hardest problems of Peirce’s semiotic scholars. According to QUEIROZ (2002, 87), there are several different opinions among scholars because of the lack of development on this subject by Peirce. He did not describe the 66 classes of signs, and in his papers more than one order to the trichotomies, and reports of doubt
about how to order them are found.

Since there must be a reason to its ordering, initially it seemed logical that the central ring could represent the ground of Sign because the semiosis process begins in it. The construction like this would bring some advantages: first, it would go perfectly in the same way Peirce described semiosis processes and ordered the ten trichotomies in a letter to Lady Welby (CP 8.344); second, it emphasizes sign in relation to object, showing that the knowing process begins in sign.

However, the diagram constructed in this way did not go well with the analyses Peirce made on the possible relations between ground of sign and immediate object in the same letter(CP 8.353-365). This happened because in the diagram the rings are ordered from the center to the border in a determining relation.

Consequently, since the object determines the sign, and not the sign determines the object, it was necessary to put the dynamical object in the central ring, followed by the immediate object and the ground of sign. Given the first three correlates, comes the first relation: between sign and dynamical object. This relation determines the possible interpretants, called immediate interpretants that when are existent become dynamical interpretants. So, the elements that compose the second relation are given: between sign and dynamical interpretant. Moreover, considering that semiosis is an infinite process, comes the place to where tends dynamical interpretant: the final interpretant and its relation to sign. Finally, given all correlates and all dyadic relations it is possible to consider the triadic relation among sign, dynamical object and final interpretant.


Once defined the order of trichotomies we can combine it with the cenopythagorean categories. The cenopythagorean categories- represented by spheres, cubes and pyramids- should take a place in every ring, starting from the central one and following the others according to the logic of categories. So, if in the first ring there is a sphere, the next one must also be a sphere. If in the first ring there is a cube, a sphere or a cube could take place in the second ring. And if in the first ring there is a pyramid, a sphere, a cube or a pyramid could take place in the following ring.


Consequently, the adoption of this trichotomic order stresses the way things are in reality, and can be a problem if a superficial reader understands that semiosis begins with a dynamical object. However, knowing that everything we can tell about the object is what sign shows, human knowledge appears in the middle of semiotic process and not in its beginning. So, putting the object in the starting point is a good way of taking man out of the center of knowledge. More than that, it does make us understand that the knowledge process is wider than human knowledge and that man cannot acquire the origin or the end of this process. Putting the object in the starting point is also in agreement with Peirce’s belief: that there is in fact a reality that does not depend on what we think of it, allowing us to call him an objective idealist. It is also in accordance to the concept of semiotic enlargement that takes the concept of intelligence far beyond human mind. In addition, the center of the rings represents the backward movement of the object and its border represents the infinite semiosis. Both create a temporal line similar to the one seen in trees.


The process of constructing the 66 classes of signs shows that signs themselves are complex structures that can increase when more details are considered. However, the classes of signs considered on its own and as an isolated system make semiotics too formal and seems an aimless work. Peirce was aware of it and did not describe all classes of signs to be considered as an isolated system. Naming signs do not solve semiotic problems but describing them in detail makes it possible to understand Peirce’s philosophy. According to Nadin (Apud SANTAELLA, 2004, p.15), “sign can only be conceived and interpreted in the range of uncertain logic and with announcement of continuum doctrine.” This diagram shows both points: in the center, the incomplete knowledge of dynamic object represents the uncertain beginning. And in the border, the growing of rings as time passes represents the growing of thoughts. Interpreting a sign is a process that produces another sign with the same capacity of being interpreted and creating signs, which brings semiotics to infinity.

4 Comments leave one →
  1. doug permalink
    May 28, 2012 7:03 am

    This is exactly what I have been tryin’ to tell people about Peirce’s work. Brilliant.

  2. March 5, 2017 2:19 pm

    Hi there! Just found this page in a search for an image of “sign determines interpretant.” I hope you don’t mind if i use your diagram in a Powerpoint series i’m making based on my netbook Turning Signs ( I’ll put a ling to your blog on mine ( and take a closer look at yours soon. Looks good!

    • priborges permalink*
      March 5, 2017 3:06 pm

      Gary, you can use the images, just give me the credit. I haven’t posted in this blog any text since 2012. However, I’ve published some articles on the American Journal of Semiotics. I have read some of your messages on Peirce-L, but I didn’t know the Turning Signs. I will look at it.

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