0115 What is the structure of a sign?

A sign is a triadic relation, where a sign-vehicle stands for a sign-object in regards to a sign-interpretant.

0116 How does this correspond to Peirce’s categories?

As a first approximation, Peirce assigns the sign-vehicle to firstness, the sign-object to secondness, and the sign-interpretant to thirdness.

That is a good start.

0117 How do the elements of sign correspond to the category-based nested form?

First, both the sign-vehicle and the sign-object are actual₂.

This implies that the sign-relation entangles two category-based nested forms.

Peirce’s first two assignments suggests that the two nested forms are separated by one level.  One expects that the sign-vehicle is on level n and the sign-object is on level n+1.  There is one exception.  If n=3 then n+1=1, rather than 4.

Peirce’s third assignment suggests that the sign-interpretant belongs to categories that are different than the sign-vehicle and the sign object.  Both the sign-vehicle and the sign-object are actual₂.  They both belong to secondness.  This leaves the sign-interpretant encompassing both thirdness and firstness.

Consequently, the sign-interpretant corresponds to the remaining categories on level n+1.  The sign-interpretant consists of the normal context_n+1 and the potential_n+1 for the actuality_n+1 corresponding to the sign-object.

0118 Here is a diagram of the general pattern.

0119 I intend to apply this pattern to the interscope of human subjectivity.

However, I cannot start with human subjectivity.  I must start with southern apes walking in mixed forest and grasslands in Africa over two million years ago.  The australopithecines walk.  Their feet are enslaved and their hands are freed.  They are about to be drawn into the niche of triadic relations.

Why?

They can address one another with manual-brachial gestures.  They pantomime.  In doing so, they image and point to natural things and events.  Their gestures are not words, yet.  However, they join in nature’s broadcast of signs.

0120 Nature’s significations decide what is happening.  So, I call them “interventional signs”.  Nature intervenes.  Nature’s significations draw our attention.

0121 The process proceeds as follows.

First, things and events themselves_2c (SV_i, sign-vehicle) stand for sensations and feelings_2a (SO_i, sign-object) in the normal context of what is happening_3a (SI_i, sign-interpretant).  

Second, these events and things_2c (SV_i) have consequences.  Consequences mean ‘something’_1a (SI_i).  Roughly, ‘something’ corresponds to the meaning of a conjunction of sign-vehicle and sign-object.

0122 In sum, nature’s broadcasts_2c (SV_i) intervene to produce a particular state of active body [substance] sensate soul_2a(SO_i) that is bound by the normal context of what is happening_3a and the possibility of ‘meaning’_1a (SI_i).