Der/die/das as demonstrative pronouns: intonation, politeness and difference with dieser/diese/dieses

Question

Three related questions:

First, I'm interested in knowing if there is any difference in the usage of der, die, das,... and dieser, diese, dieses,.... For instance

z.B. Ich habe zwei Hunde. {Der |Dieser } (hier) ist leider schon sehr krank.

The second question: is it appropriate to use der, die, das, usw. and/or dieser, diese, dieses, instead of er,sie,es, for persons?

z.B. {Der | Er | Dieser } behauptet, seine Schwester habe Aberhundert Preise gewonnen.

And third: when der, die, das are demonstrative pronouns, must they be pronounced with a particular emphasis? At least, in that function, I've always heard them so: really stressed (higher pitch and I'm not sure if longer duration as well).

z.B. Ich gehe in die Richtung.

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This question emerges as a complement to one of the answers to this question.

Answer 1

With regards to the third question, the emphasis isn't generally required, but common depending on the context. The verbal emphasis is more likely to be used when it hasn't been previously established exactly what the pronoun refers to, or as a means to strongly disambiguate (often combined with non-verbal clues). Which is another way of saying that you'd use the verbal emphasis if whatever the pronoun refers to has a significance above and beyond establishing what the pronoun refers to.

E.g., if you want to communicate the direction you're headed to as a simple statement of fact, the emphasis isn't needed. In a scenario where the direction you're headed matters for some reason or other (say there's disagreement about which way to go), then the emphasis is warranted.

As far as the second question is concerned:

Der behauptet, seine Schwester habe Aberhundert Preise gewonnen.

Our teacher fought losing battles against language like this. Whether it's grammatically correct or not, as mentioned by others in some regions it's idiomatic usage, in others it's derogatory or bordering on it. "Er behauptet..." is the more proper form. I would use "Dieser behauptet..." if I wanted to express detachment to the person referred to.

If you wish, "Er behauptet..." puts an emphasis on the person whose statement I relay, "Dieser behauptet..." is a phrasing I'd expect in a report about somebody.

And back to the first question. To me, in the example

Ich habe zwei Hunde. {Der |Dieser } (hier) ist leider schon sehr krank.

both forms are interchangeable to me; similarly to above "Der (hier)..." hints at a personal interest in or relationship with the dog in question, "Dieser (hier)..." sounds more clinical.

Answer 2

First:

To the first question. Using "der" in this context would be inappropriate, as it suggests singular: on the other Hand would "dieser" suggest the choice of one element from a variety of others, which would be inappropriate with a single dog.

"Dieser" is often combined with a complement like "jener" to show a duality in between the chosen elements. z.B.:

Ich habe zwei Hunde. Dieser / Der eine ist ein Labrador-Mischling,  
jener / der andere ist ein Terrier.

When referring to positional elements or previously mentioned subjects, dieser refers to the closer (in location or text)

Example:

Jan mag Cola. Georg mag Pepsi. Dieser (Georg) mag Computerspiele, jener (Jan) mag sie nicht.

In brackets is the explicit naming of the referred subject.

Hier stehen zwei Säulen. An dieser (der näheren) klebt ein Plakat.

When using "Der" in a sense of "Dieser" this is normally accomplished by pointing to the referred Subject, as "Der" requires exact definition.

Second:

Simply said: Not with "Der" / "Die" / "Das" standing alone. As mentioned in the Answers here and here it is more common in southern Germany, but generally considered bad style, when used with a Name in front of other people.

It gets even worse without a name. That is generaly considered very impolite and sometimes derogative. As @Emmanuel pointed out this form is quite popular in written language to refer to a previosly introduced Person, or when referring to the "position" of a person:

His Example:

Der Oppositionsvorsitzende warf XY Korruption vor. Der wiederum bestritt den Vorwurf entschieden.

In this case "Der" is referring to the already introduced "party" XY and takes a function similar to "Dieser". Thus it is not derogative or even impolite, oppositely it is good style to evade reusing the same word again and again.

You can of course use "Dieser" / "Diese" / "Dieses", but only when referring to a previosly introduced Person. Sometimes this is done by showmasters introducing their candidates.

Dieser Kandidat hier wettet, dass er einen Traktor auf 2 Rädern durch einen
Hindernisparcours steuern kann.

Third:

No in general not. as @wrzlprmft mentioned you should of course emphasise it a little bit, else one could think of "Die Richtung" as some restaurant.

One can of course always add additional stressing to mark you are doing something special, but that is not required.