Icon, Likeness, Likely Story, Likelihood, Probability

[Jon Awbrey]

Icon, Likeness, Likely Story, Likelihood, Probability • 1
• https://inquiryintoinquiry.com/2026/05/17/icon-likeness-likely-story-likelihood-probability-1-a/

Here's a likely locus classicus for “icon” in its logical sense —

❝A probability (εικος) is not the same as a sign (σηµειον).
The former is a generally accepted premiss; for that which
people know to happen or not to happen, or to be or not to be,
usually in a particular way, is a probability:

❝For example, that the envious are malevolent or
that those who are loved are affectionate.

❝A sign, however, means a demonstrative premiss which is necessary
or generally accepted. That which coexists with something else,
or before or after whose happening something else has happened,
is a sign of that something’s having happened or being.❞

(Aristotle, Prior Analytics, 2.27.70a3–10).

Reference —

Aristotle, “Prior Analytics”, Hugh Tredennick (trans.), pp. 181–531
in Aristotle, Volume 1, Loeb Classical Library, William Heinemann,
London, UK, 1938.

Resource —

Theme One Program • User Guide • Appendix A
• https://www.academia.edu/5211369/Theme_One_Program_User_Guide

Regards,

Jon

cc: https://www.academia.edu/community/LgG81v
cc: https://mathstodon.xyz/@Inquiry/116596299326860503
cc: https://www.researchgate.net/post/Icon_Likeness_Likely_Story_Likelihood_Probability

[Jon Awbrey]

Icon, Likeness, Likely Story, Likelihood, Probability • 2
• https://inquiryintoinquiry.com/2026/05/19/icon-likeness-likely-story-likelihood-probability-2-a/

Re: Peirce List • Phyllis Chiasson
• https://web.archive.org/web/20131211153209/http://comments.gmane.org/gmane.science.philosophy.peirce/11234
• https://web.archive.org/web/20131211034001/http://permalink.gmane.org/gmane.science.philosophy.peirce/11235

I'm still a bit fuzzy on how Aristotle's account relates
to Peirce's usage, though I'm pretty sure Peirce must have
taken Aristotle's usage into account, but it does seem that
Aristotle drew some sort of distinction here, using a term
“tekmerion” which gets translated as “index” to make the
following remark later on in that chapter.

❝We must either classify signs in this way, and regard
their middle term as an index [τεκµηριον] (for the name
‘index’ is given to that which causes us to know, and the
middle term is especially of this nature), or describe the
arguments drawn from the extremes as ‘signs’, and that which
is drawn from the middle as an ‘index’. For the conclusion
which is reached through the first figure is most generally
accepted and most true.❞ (Aristotle, Prior Analytics,
2.27.70b1–6).

Reference —

Aristotle, “Prior Analytics”, Hugh Tredennick (trans.), pp. 181–531
in Aristotle, Volume 1, Loeb Classical Library, William Heinemann,
London, UK, 1938.

Resource —

Theme One Program • User Guide • Appendix A
• https://www.academia.edu/5211369/Theme_One_Program_User_Guide

Regards,

Jon

cc: https://www.academia.edu/community/VB239Z
cc: https://mathstodon.xyz/@Inquiry/116607167143530700
cc: https://www.researchgate.net/post/Icon_Likeness_Likely_Story_Likelihood_Probability

[Jon Awbrey]

Icon, Likeness, Likely Story, Likelihood, Probability • 3
• https://inquiryintoinquiry.com/2026/05/23/icon-likeness-likely-story-likelihood-probability-3-a/

The passages from Aristotle collected in the present and preceding
two posts prepare the way to address overarching tasks in Peirce's
Logic of Science, namely, bringing the Theory of Signs and the
Theory of Inquiry into their proper relationship and extending
Pure Deductive Logic to Probable Reasoning, continuing the
groundbreaking work of Boole's Laws of Thought.

Re: Peirce List • Phyllis Chiasson
• https://web.archive.org/web/20131211153209/http://comments.gmane.org/gmane.science.philosophy.peirce/11234

• https://web.archive.org/web/20131211153053/http://permalink.gmane.org/gmane.science.philosophy.peirce/11238

A more complete excerpt and the translator's notes are very helpful here.

❝A probability (εικος) is not the same as a sign (σηµειον). The former
is a generally accepted premiss ; for that which people know to happen
or not to happen, or to be or not to be, usually in a particular way,

is a probability : e.g., that the envious are malevolent or that those

who are loved are affectionate. A sign, however, means a demonstrative

premiss which is necessary or generally accepted.[1] That which coexists

with something else, or before or after whose happening something else
has happened, is a sign of that something's having happened or being.

❝An enthymeme is a syllogism from probabilities or signs ; and
a sign can be taken in three ways — in just as many ways as
there are of taking the middle term in the several figures :
either as in the first figure or as in the second or as
in the third.

❝E.g., the proof that a woman is pregnant because she has milk
is by the first figure ; for the middle term is ‘having milk’.
A stands for ‘pregnant’, B for ‘having milk’, and C for ‘woman’.

❝The proof that the wise are good because Pittacus was good is by
the third figure. A stands for ‘good’, B for ‘the wise’, and
C for Pittacus. Then it is true to predicate both A and B of C ;
only we do not state the latter, because we know it, whereas we
formally assume the former.

❝The proof that a woman is pregnant because she is sallow is
intended to be by the middle figure ; for since sallowness
is a characteristic of woman in pregnancy, and is associated
with this particular woman, they suppose that she is proved to
be pregnant. A stands for ‘sallowness’, B for ‘being pregnant’,
C for ‘woman’.

❝If only one premiss is stated, we get only a sign ; but if the
other premiss is assumed as well, we get a syllogism,[2] e.g.,
that Pittacus is high-minded, because those who love honour
are high-minded, and Pittacus loves honour ; or again that
the wise are good, because Pittacus is good and also wise.

❝In this way syllogisms can be effected ; but whereas a syllogism
in the first figure cannot be refuted if it is true, since it is
universal, a syllogism in the last figure can be refuted even if
the conclusion is true, because the syllogism is neither universal
nor relevant to our purpose.[3] For if Pittacus is good, it is
not necessary for this reason that all other wise men are good.
A syllogism in the middle figure is always and in every way refutable,
since we never get a syllogism with the terms in this relation[4] ;
for it does not necessarily follow, if a pregnant woman is sallow,
and this woman is sallow, that she is pregnant. Thus truth can be
found in all signs, but they differ in the ways which have been
described.

❝We must either classify signs in this way, and regard their

middle term as an index (τεκµηριον)[5] (for the name ‘index’ is

given to that which causes us to know, and the middle term is
especially of this nature), or describe the arguments drawn

from the extremes[6] as ‘signs’, and that which is drawn from

the middle as an ‘index’. For the conclusion which is reached
through the first figure is most generally accepted and most true.❞

(Aristotle, Prior Analytics 2.27, 70a3–70b6).

Translator's Notes —

❝1. If referable to one phenomenon only, a sign has objective
necessity ; if to more than one, its value is a matter of opinion.

❝2. Strictly an enthymeme.

❝3. If the signs of an enthymeme in the first figure are true,
the conclusion is inevitable. Aristotle does not mean that
the conclusion is universal, but that the universality of the
major premiss implies the validity of the minor and conclusion.
The example (<all> those who have honour, etc.) quoted for the
third figure contains no universal premiss or sign, and fails
to establish a universal conclusion.

❝4. i.e. when both premisses are affirmative.

❝5. Signs may be classified as irrefutable (1st figure)
and refutable (2nd and 3rd figures), and the name ‘index’
may be attached to their middle terms, either in all figures
or (more probably) only in the first, where the middle is
distinctively middle.

❝6. Alternatively the name ‘sign’ may be restricted to the 2nd
and 3rd figures, and may be replaced by ‘index’ in the first.❞

Reference —

Aristotle, “Prior Analytics”, Hugh Tredennick (trans.),
pp. 181–531 in Aristotle, Volume 1, Loeb Classical Library,
William Heinemann, London, UK, 1938.

Resource —

Theme One Program • User Guide • Appendix A
• https://www.academia.edu/5211369/Theme_One_Program_User_Guide

Regards,

Jon

cc: https://www.academia.edu/community/l74YKP
cc: https://www.researchgate.net/post/Icon_Likeness_Likely_Story_Likelihood_Probability