Argument from NATURAL SIGN
A natural sign is a perceptual datum, an actual material fact or object, that is materially connected, either necessarily or ambiguously, to another fact or object or state of things that is not perceptually accessible.
Natural signs are typically undeniable facts, “as certainties, we have, in the first place, what is perceived by the senses, such as what we see, what we hear, as signs [signa] or indications” (Quintilian, V, 10, 12).
Natural signs are quite different from linguistic signs, in which the link between signifier and signified is social and arbitrary, nor are they global analogues of what they “represent”, as in the case of analogical thought. Nor are they a symbolic representation of the associated phenomenon.
The natural sign is merely a part of the phenomenon through which the observer can access the whole phenomenon as a whole. The connection between the present natural sign and its absent counterpart may be:
The very first manifestation of a phenomenon: a red setting sun / rainy weather tomorrow.
A remnant of something that has disappeared: the leftovers / the meal.
A part of a whole: a strand of hair / a person.
An effect of a cause: being tired / having worked.
1. Natural signs, clues and traces
Clue is an accurate synonym for material sign, since looking for clues involves an “intricate procedure or maze of difficulties”, or be trying “to find something, understand something, or solve a mystery or puzzle” (MW, Clue). These descriptions fit well with exploratory argumentative situations. Generally speaking, an argument is a clue to a conclusion.
Etymologically, a clue is ‘a ball of thread’; hence, one used to guide a person out of a labyrinth” (OD, Clue). Clues are typically sought “in the detection of a crime”: “police officers are still searching for clues” (ibid.). However, clue is also used to refer to a “piece of information” given to someone, which is not a natural sign in the sense discussed in this entry.
Traces, such as fingerprints (necessary signs), or tire marks (probable sign), are a special kind of natural sign. However, insofar as traces are remnants, “a mark […] left by something that has passed”, not all material signs are traces; smoke is a correlate of actual fire, not a trace of fire — but but ashes are.
Index, indication and indicator can also be used in the sense of “natural sign”.
2. Reasoning on probable and necessary signs
The relationship between a natural sign and its counterpart is inferential in nature:
Anything that [when it is, another thing is, or when it has come into being the other has come into being before or after], is a sign of the other’s being or having come into being.
(Aristotle, P. A., II, 27; my italics for the sign and underlining for the counterpart).
A tentative reformulation: α is a sign of another thing A, if when α is the case, then A is the case; or when α occurs, then A is about to occur or has just occurred
In the Aristotelian system, enthymemes are developed from natural signs and probabilities (P. A., II, 27); see enthymeme; probable.
These inferences are used in concrete arguments, such as:
I can see smoke, the house must be on fire.
Peter’s face is flushed, he must have a fever.
The quality of the argument depends on the nature of the link used. If the sign is necessary, the argumentat is conclusive. If it is probable, the possible claim is somewhat more probable than it would be without the argument. Probable signs reduce uncertainty, see abduction.
Probable signs are distinct from human and social probabilities.
— A necessary sign (tekmerion) is associated with a material entity or state of affairs. It corresponds to material, empirical necessity (not logical necessity):
A scar / an old wound.
Calloused hands / being a workman.
Smoke / fire.
Footprints in the sand / people on the island.
Such signs thus have the force of proof, the associated syllogism is valid, as in the following propter quid argument, see. a priori
Law (major): A woman who has milk has given birth (if M, then B)
Sign (minor): This woman has milk.
Conclusion: This woman has given birth.
— Probable (contingent) signs (semeion) can correspond to several related independent realities. Contingent signs are ambiguous, whereas necessary signs are unambiguous
Being tired is a possible sign of having worked.
Being flushed is a possible sign of having a fever.
Typically, peripheral indicators are not necessary signs: “He has a guilty look so he must be feeling guilty, so he is guilty”, see circumstances. The corresponding syllogism is not valid:
Law: Women who have given birth are pale.
Sign: This woman is pale.
Conclusion: This woman has given birth.
A necessary condition is considered sufficient: one may simply have a naturally pale complexion, or one may be pale because one is ill. The probable sign is only a fragment of evidence (judicial); it can support a suspicion, but it is not a proof.
The human body is an inexhaustible source of natural signs. White hair and flexible skin are natural signs that indicate the person’s age and general physical condition. In medicine, co-occurring unnecessary signs are grouped into a syndrome, which is defined as “a group of signs and symptoms that occur together and characterise a particular abnormality or condition” (MW, Syndrome). For example, Samter’s syndrome
Samter’s Triad also known as aspirin-sensitive asthma, is a chronic disorder consisting in asthma, recurrent sinus disease with nasal polyps, and a sensitivity to aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs).[1]
The presence of these three conditions together provides a basis for a conclusive medical reasoning: if a patient has asthma and is sensitive to aspirin, it is highly likely that they will also have nasal polyps. They should be evaluated for this third condition.
Individually these signs may be inconclusive, but taken together, they can form a body of conclusive evidence. For example, an area of the body may be red, because it has been rubbed; hot, because it is starting to burn; painful or swollen because of an accidental blow. But if it is red, painful, hot and swollen at the same time, then we can say that it is inflamed, see convergent argumentation.
In the following passage, to guess the enemy’s intentions, the soldier observes their actions and movements, deducing a conclusion from a cluster of converging signs.
The writer Roland Dorgelès had “the singular privilege of baptising a war”, as “the Phony War” [la drôle de guerre], referring to the strangely calm situation on the front between September 3rd 1939, the date of the declaration of war, and May 10th 1940, the date of Nazi’s Germany’s invasion of Belgium, the Netherlands, Luxembourg and France. His book, The Phony War, is a series of reports from the front during this period. In April 1940 he was stationed at an observation post in Alsace.
Looking down on the enemy lines from above was like looking down on the enemy lines from a balcony. The sergeant who never lost sight of the ennemy, now knows their habits, where they came from, and where they went.
‘There, he points out, they are digging a sap. Look at the disturbed earth… That gray house has certainly been reinforced… Look at the embrasures… And what about those tiles over there? Most of the workers are there right now. I counted sixty of them, coming back from the site with lamps this morning: so they must be digging underground.