I think it might be better to just have all subjects on this in one thread - not that i expect much posting, or that the thread will be updated often 
So, to begin in media res:
The fifth week of the second circle of my lectures/presentations begun yesterday, so here is a brief post about the current focus of those...
What the notion of a "thing-in-itself" generally signifies in philosophy
The thing-in-itself is one of the most common (and persistent) phrases in philosophy. It originates at least since the time of Socrates, when it is attributed to Parmenides of Elea. However as a notion (even if not in the particular phrasing) it is already there one century before Parmenides, in the beginning of the 6th century BC, the city of Ephesos in Ionia, and Heraklitos.
A brief account, with an example, of a thing-in-itself used as a notion in philosophy.
The terms connote a number of things. First of all that there is a theorised juxtaposition between a view we have of an object, and the reality of that object. This applies to all kinds of objects, but the simplest example are some material, for example the desk your computer is on seems to have a number of qualities such as form, color, relative lack of elasticity, extent in space and so on. From a human point of view, and more specifically your own, it seems to have set qualities on categories such as those. However this ultimately has little (or perhaps even none at all) relation to the object being something by itself, cause that means it being something without a set observer identifying what it is.
So the desk would have no color for you if you were blind, have no shape or surface type if you were further immobile, have no known existence in a blackened space where you did not even know it existed, but all those are still in regards (more precisely in juxtaposition) to you as a potential observer of it. But more than that, the desk as a pure thing-in-itself has no known qualities, cause a thing-in-itself is the idealised and hypothesised object when it would have been there without any observation of it from any point of view which would be finite (or even existent). It is, in essence, a barrier past the realm of human thought, and a notion tied to what is currently termed as "Idealism" (for better or worse; since the theory of ideas by Plato itself is a horrible translation of the theory of Eide; Eide meaning 'categories' and they are not parts of human thinking according to Socrates and Plato).
Why the thing-in-itself is not just a notion in Idealism which focuses on a 'truth'
It is worth noting that the idea of a thing-in-itself was not presented (eg by Parmenides) out of some despair, or negation of the will to keep on thinking about the reality of things. In fact Parmenides begins (most of his own work is lost) with the premise that human observers are eternally locked out of the ability to examine -or even know, to most degrees- reality. The thing-in-itself in Parmenidian philosophy (eg the eponymous socratic dialogue) mostly takes the position of a shadow of a barrier between human thought and anything which is beyond it and thus can identify and examine "reality". Parmenides uses the term as something highlighting a thin vista of dancing shadows in the perimeter of that eternal border between reality and illusion, with humans never able to look past the final horizon of illusion.
So, to begin in media res:
The fifth week of the second circle of my lectures/presentations begun yesterday, so here is a brief post about the current focus of those...
What the notion of a "thing-in-itself" generally signifies in philosophy
The thing-in-itself is one of the most common (and persistent) phrases in philosophy. It originates at least since the time of Socrates, when it is attributed to Parmenides of Elea. However as a notion (even if not in the particular phrasing) it is already there one century before Parmenides, in the beginning of the 6th century BC, the city of Ephesos in Ionia, and Heraklitos.
A brief account, with an example, of a thing-in-itself used as a notion in philosophy.
The terms connote a number of things. First of all that there is a theorised juxtaposition between a view we have of an object, and the reality of that object. This applies to all kinds of objects, but the simplest example are some material, for example the desk your computer is on seems to have a number of qualities such as form, color, relative lack of elasticity, extent in space and so on. From a human point of view, and more specifically your own, it seems to have set qualities on categories such as those. However this ultimately has little (or perhaps even none at all) relation to the object being something by itself, cause that means it being something without a set observer identifying what it is.
So the desk would have no color for you if you were blind, have no shape or surface type if you were further immobile, have no known existence in a blackened space where you did not even know it existed, but all those are still in regards (more precisely in juxtaposition) to you as a potential observer of it. But more than that, the desk as a pure thing-in-itself has no known qualities, cause a thing-in-itself is the idealised and hypothesised object when it would have been there without any observation of it from any point of view which would be finite (or even existent). It is, in essence, a barrier past the realm of human thought, and a notion tied to what is currently termed as "Idealism" (for better or worse; since the theory of ideas by Plato itself is a horrible translation of the theory of Eide; Eide meaning 'categories' and they are not parts of human thinking according to Socrates and Plato).
Why the thing-in-itself is not just a notion in Idealism which focuses on a 'truth'
It is worth noting that the idea of a thing-in-itself was not presented (eg by Parmenides) out of some despair, or negation of the will to keep on thinking about the reality of things. In fact Parmenides begins (most of his own work is lost) with the premise that human observers are eternally locked out of the ability to examine -or even know, to most degrees- reality. The thing-in-itself in Parmenidian philosophy (eg the eponymous socratic dialogue) mostly takes the position of a shadow of a barrier between human thought and anything which is beyond it and thus can identify and examine "reality". Parmenides uses the term as something highlighting a thin vista of dancing shadows in the perimeter of that eternal border between reality and illusion, with humans never able to look past the final horizon of illusion.
