The last section was about the fact (or the position) that information exists, independently of whether it is understood. Now,some question arise: What is the content of information, how does it come about, and what does it mean to understand it?
Let us first look again at an example of the effect and transfer of information (information acts by being transferred). Information, we said, is form or structure. By experience with tools, we know that something has an effect because of its form: The cutting effect of a knife has less to do with the power applied in cutting, but rather with the form of the blade: its profile is a sharp wedge. The material of the blade is basically irrelevant, it must only be more solid than that what shall be cut.
When I cut an apple into halves by the knife, then the smooth surface of the blade causes smooth cut faces of the apple halves. The smooth cut faces of the halves are a natural sign of the fact that the apple was cut but not broken into halves. The tern ‘natural sign’ only means that it is not a sign deliberately produced as a sign (with a defined meaning).
It is not at all the nature of the smooth cut faces to be a sign. Instead, they are a sign only for someone who knows what a knife is – for an ‘understanding system’ which knows that such smooth surfaces of apple halves are (usually) caused by cutting with a knife (I use the term ‘understanding system’ and not, e.g., ‘intelligent system’ because it is a matter of debate whether intelligence – especially artificial intelligence – implies semantic understanding). Another example: Is smoke, in and of itself, a sign of fire? No, it isn’t. It’s a sign only for an understanding system which knows that smoke is (usually) caused by fire . A similar example is the following one, instanced by Fred Dretske:
“If things are working properly, the ringing of my phone tells me that someone has dialed my number. It delivers this piece of information.” 
No, the telephone does not say anything, it only rings. The conclusion that someone has (just now) dialed my number is only possible if I already know that the phone rings if and only if someone dials my number (given that things work properly). Dretske indeed believes that information exists independently of whether it is understood, but he assumes a correlation between knowledge and information, which, in my view, implies a lawful relationship between information and understanding. Dretske writes:
“One needs only to stipulate that the content of the signal, the information it carries, be expressed by a sentence describing the condition (at the source) on which the signal depends in some regular, lawful way.” 
The crucial point, however, is: Information, i.e., a form or structure carries a content only in a syntactic way, that is, only as a form or structure. Its semantic content, its meaning is generated by understanding and is depending on the context in which the information is interpreted by an understanding system.
This is true even if a form or structure is definitely meant as a sign or signal. When the fire siren is sounding “– – – – – – – – –“ (in Germany), then I must know what the sound means, otherwise it doesn’t tell me anything. The meaning is not contained in the signal. The sentence Dretske mentions – the sentence describing the condition at the source, here: the alarm was set off because there’s a fire – can be formulated only by someone who knows what the signal means.
What is the content of an information, and how does it come about? Dretske is right with his assumption that the content of an information is nothing else than the cause or the reason which generated or evoked the form or structure – the condition at the source. What caused my telephone to ring was the fact that someone dialed my number – and just this is the content of the information: I get that someone calls me – but only because I already know by which the ringing is elicited, that is, because I know the conditions on which the signal depends.
The new I learn when my phone is ringing is that someone is calling me just now, at this moment. I derive this new from my knowledge about the causal relationship between the two events: My phone rings always when my number is dialed. Whether and how an information is understood is therefore depending on whether the receiver has a knowledge from which the specific meaning of the information can be logically derived. Some further examples may illustrate this:
When a geologist regards a stone, any simple field stone, then he can recognize by its color and structure what it consists of, how old it is, if it was formed by volcanism or by sedimentation, and – if the stone is from the North German lowlands – from which region in Scandinavia it was moved to the south in the glacial period. The geologist is able to recognize all this because he has a general knowledge of what colors and structures of stones tell us about their genesis, age, and origin. On the basis of that general knowledge, he can understand the information, the color and structure, of a particular stone. The stone ‘talks’ to him because he understands ‘the stones’ language’. If I, by contrast, looked at the stone, I would assume it could tell me a lot, but I don’t understand its language.
The same would, however, be with a Japanese talking to me in his native language: I have neither a general knowledge of what Japanese words mean nor a general knowledge of Japanese sentence construction, that is, I lack the knowledge from which I could derive the meaning of a particular message, thus I don’t understand anything. Nevertheless I do not doubt that the man’s speech, these sound waves reaching my ears, are information and have a content. Obviously, there is no basic difference for the receiver between information produced as a message (e.g., by another person) and information simply present in nature . The crucial thing is to be an understanding system in regard to a given information, that is, to have just that general knowledge from which the meaning of the given information can be derived.
Let’s summarize: Information, as such, is not a sign or signal. Information does not carry a meaning, but gets a meaning or becomes a signal only by understanding. However, information – form or structure – objectively result from the causes by which, or from the reasons because of which they were formed or structured. Information refers to these causes or reasons, that is, to something different from themselves. In that sense, information has an intentional content. But content is not meaning – meaning is the result of an ‘act of understanding’ Tom Stonier writes:
“If information has an independent reality, meaning does not. Meaning involves the interpretation of information in relation to some context.” 
It is important to distinguish between causality in information transfer (as described in the last section) and understanding. It is only appropriate to refer to a process as ‘understanding’ if misunderstanding and error are possible in this kind of process. We will hardly (seriously) say about a computer that it misunderstands something, as we are sure: When “Error” is displayed on the screen, it is never an error made by the computer, but a designer’s, programmer’s, or user’s error, or a defect . A man who is mistaken is not defect – our ability to misunderstand is only the flipside of our ability to understand. What the nature of this ability is and on what it depends will be theme of the next chapter.