I am not entirely sure if this is the appropriate site and whether these are the appropriate tags for this topic, so if that is not the case, please feel free to let me know.
I never thought twice about how reading and writing works until recently and wondered whether how I think it works is actually correct. The way one usually learns reading requires that one previously learns the spoken form of a language. That way one has already attached sounds to a meaning, for example the sound /kæt/ (of cat) to the concept/to an image of a cat. Now, strictly speaking, words are only strings of symbols. That is, the word "cat" is only a string of the symbols "c" "a" and "t". Each of these "atomic symbols" are called letters and are associated with a certain sound. By combining the sounds of the letters that make up the word, we end up with a sound. If we are familiar with the semantics of that sound, that is, with the meaning of the word, we associate a meaning with that word. So when reading the string "cat", we associate with it the sound /kæt/ and with that sound the meaning of a cat. This is basically how I have always read - I translated the symbols/strings to sounds and those sounds have a meaning. That way I know what these symbols try to tell me. That is how I think reading usually works.
Writing is sort of the inverse process. We have some words/sentences that we want to express. These are usually in the form of sounds. To stick to the cat example, without spoken language I would need to point to a cat and make the sound /kæt/ and hope that the person I am trying to communicate to understands that I want to attach the sound /kæt/ to the concept of a cat. Now, when one has learnt the spoken language this is done already. So when one wants to communicate some phenomenon, one expresses that phenomenon into sounds and these sounds into symbols/letters. These are exactly those letters that when read produce the sounds of the thing I wanted to communicate. In the cat example, I know that the string "cat" is pronounced /kæt/, so when I want to write this down, I need to go exactly through this process.
Now what I find fascinating is that all of this happens unconsciously now that we have learnt this and that probably everyone takes this for granted. The processes I describe above are not trivial in my opinion, which makes this pretty impressive, despite being used every day.
Having thought about this and having a mathematical background, I am particularly interested how true statements and logical consequences are communicated. Consider a simple statement like "Today I woke up at 7 am". I already used the word statement, however at first this is only a string of symbols. Trying to read these symbols I get a sound which associates the meaning that I woke up at 7 am today. I can now ask whether these symbols give a true statement, but what does it mean for these symbols to be a true statement? I guess it means that the spoken statement associated with the string of symbols is true, and this in turn means that the meaning of the spoken statement is true. So when communicating facts in written form, we have a phenomenon, sounds that describe that phenomenon, in this case the sound associated with the sentence "today I woke up at 7 a.m.", and a way to turn these sounds into symbols/written form. By the above, the written symbols are true if and only if the phenomenon it is associated with through the sounds is true. This means that when judging whether a written statement is true, we translate it into sounds, check if what the sounds represent is true and then we know whether it is indeed true or not. When trying to deduce things logically from a written statement such as "today I woke up at 7 a.m." one checks which semantic implications these symbols have. This is done by again, translating these symbols into sounds, then these have a meaning and this meaning may imply other meanings, for example the meaning of "I had enough time to shower at 7:05 a.m.". In summary, one would say that the written symbols "Today I woke up at 7:05 a.m., so I had enough time to shower at 7:05 a.m." are a true statement, because the meaning associated with the sounds of the symbols is true. In particular, someone reading this statement other than me could check the truth by translating the symbols into meaning and checking whether the meaning is true.
So in summary, how deduction with written premises works is, one translates these premises to sounds and these to meaning, which may imply other things to be true as well. These implications can be turned into sounds and then into written form again.
I would like to know whether what I came up with regarding this topic is somewhat correct or completely wrong and gain more insights into all of this, which is why I would appreciate any links to further material. Since I am not a linguist at all and previously never really thought about any of this consciously I am sorry if I am imprecise in some sections. Again, feel free to ask for clarification if anything is unclear. Thanks in advance!