Reading my answer to the question is best preceded by reading these texts first because I will reference to them with examples.
I am excluding onomatopoeia in this answer.
When you have read all the views on arbitrary language (the pratclif link), eventually the author writes: “Some signs are absolutely arbitrary; in others we note not its complete absence but the presence of degrees of arbitrariness: the sign may be relatively motivated, for example, 'vingt' is relatively less motivated than 'dix-neuf' (which by its form refers to other forms) ... but even in the most favourable cases motivation is never absolute ...”
So if we don’t know or can not find a motivation, the word must be arbitrary? That is like saying I am blind so light can not exist. What if all words have a motivation? Sure we may have lost the motivations of most of the words in languages, but that does not mean they don’t exist. Here is where people ‘believe’ my methods are based on coincidence, nonsense, twaddle and whatever terminology can be used to keep up the misconception that words are arbitrary. If we don’t see words as combined phonetic elements with descriptive meaning we can not analyse if there is a natural origin or motivation for each sound/syllable within the word connected to meanings. I write ‘meanings’because I suspect multiple basic meanings for each sound. So stating that most words are arbitrary is at least premature. And I must confess that the evidence for my motivations is empirical. We are humans and language is a skill in which we stand out. We give meaning to signs. And if we intend meaning we intend motivation.
So, what is the challenge we have?
What if there are absolute motivations for each word?
What if people just lack the ability to identify them all? This inability to identify them puts the mass of valuable data and possible outcomes in the bin, because it is not understood as the seminal thought author points out. However his example ‘vingt’ (20) can similarly be motivated as dix-neuf (19 literally ten-nine) referring to two other forms. Vingt is a corrupted compound of Latin ‘quinque quattuor’ which forms show the initial speaker’s intention of conveying a multiplication: 5 x 4 to be 20. This is common in French counting because 80 is expressed as quatrevingt which literally says fourtwenty (4x20=80 so not a sum but another motivated multiplication). An English speaker not knowing this difference in counting can easily claim ‘vingt’ to be a more or less arbitrary word.
If we leave out the culture in the analyses, we are again blind for what use the word has in a language. If we include culture we can motivate why ‘dog’ is based on observing the behaviour of the animal ‘digging’ holes, while ‘hound’ can be motivated by the animal’s use in ‘hunting’ and ‘perro’ is the guardian of the ‘house’ just like ‘Canis’ can be motivated by the animal’s use in protection by its ‘teeth’, while ‘kalba’ is motivated by observing the animal produce ‘saliva’: drewl. The treatment of dogs within the cultures using these languages coincides with the level of usefulness to humans. In northern Europe the dog was used in hunting and thus providing important food especially in the winter. The dog culturally became a friend of humans. In Arabic countries living a dog’s life is not easy and this can be understood by its name; his drewling not being a useful function for humans. It was not used as extensively in hunting as in the north. And in Southern Europe the animal was used less in hunting but more in protection of the house and land. Hence a motivated connection with teeth and house.
A noun is a descriptive name often based on a quality of the context it signifies. And from
that description it is possible to analyse older meanings for the single phonemes by comparing their use across languages.
I found that in husbandry (motivated by compounding the descriptive location of the animals: house & boundary) naming of animals follows certain specific rules. The word for a 🐈 being ‘cat’ in English is not arbitrary, neither natural. It is cultural. There is no direct link between the form and the meaning of cat. There is a direct link though between the name of the animal and its use for humans. A cat/Katze catches mice. The motivation of the word ‘cat’ is found in the cultural context of the usefulness of the cat catching mice. Cat is than cognate to ‘chase’, French ‘chasse’ (hunt) and Spanish ‘caza’ (hunting/chase) and even ‘casa’ (house), which in extension encloses the sleeping place (instead of rodents).
You asked about one example where a sound carries a specific meaning. This essentially is the biggest question of all. How did the first sounds link to the first meanings? If we consider the development of language as a string of DNA, we have to analyse each word to its origin until there are only single sounds to designate meaning to. That is painstaking work. Something that should be done by computers but as it is a hobby of mine I have done a bit myself. I am not ready but can claim a handful. There are 2 that I suspect are the sounds copied from our environment and they fortunately share a context which makes the case a bit stronger. This does not mean that it is the only natural meaning to the sound, because there are many linguistic developments that give more possibilities. These sounds are /v/ (sometimes /f/) and the /n/.
The /v/ dominate words that have to do with flying in Germanic languages. In Semitic it is found in the context of heaven in Hawwah (Biblical Eve) which means ‘snake’ and ‘sky’. Two meanings related by the sound of air if directed by blowing through the mouth. French ‘vent’ and English ‘wind’ (sound change). So whistling and blowing air most probably became the natural origin for the sound /v/ in parole and language. And if used in descriptions that compounded to names and verbs, this would explain the relation between a phoneme in a word and similar meanings within different contexts.
/n/ is the nasal sound. Based on the evidence above one would expect the /n/ to dominate the nouns meaning ‘nose’ in different languages which it still does. It is found in the Arabic word for breath (a function of the nose) and English ‘sneeze’. The verbs ‘to smell’ and ‘to smoke’ use different phonemes that can be found in the Hebrew word for sky (Shamash). The letter Samek is said to derive from a support, thus lifting something. The skyward context can be noted again. It is very hard to motivate all words with an /n/, but the words ‘no’ and ‘not’ (nicht in German) are based on ‘night’. Yes is harder to motivate because the connection with ‘day’ is harder to see at first sight. But that is the context where we have to look. The ‘eyes’ and ‘yes’ are cognate. Compare:
French: oui and ouil
Greek: μάτι versus French matin
Greek: όχι versus oog (eye in Dutch)
But in Greek the sounds for these meanings seem switched. Greek όχι (no) seems cognate with ‘oké’ which is in itself strange because they are antonyms and we could associate Yes with the presence of light and no with the absence of light (night). Greek Yes is Ναί. A choice that amazes me. But it shows how cultures invent or invert or substitute meanings, contexts, forms and everything out of unknown reasons (word play, political, religious or other). It is just one of many underlying ways words and sounds are related to meaning. So like I said painstaking.
What is the evidence for the arbitrairiness of a sign?
The answer must be, the lack of or inability to find motivations for words through qualities of the concept.
Add to that unwillingness (people calling my research outcomes coincidence, nonsense, twaddle and whatever terminology that does not support rational, logical and argumented reasoning and evades dialogue.
On a personal note:
Draconis, I Thank you for your attitude which has always been informative, critical and investigative. You have been an island of tolerance here. And your question motivated me to determine where I stand in the realm of linguistic research by comparing my ideas to others. Thanks also to anyone editing this as I am not a native speaker of English.