-isch adjective ending and instrumentality

Question

Firstly, I apologise if I am completely off mark, as I am trying to teach myself German whilst simultaneously being rather new to it.

I was trying to better understand adjectival suffixes, and found this post to be particularly useful.

What particularly caught my eye was the explanation concerning the use of the ending -isch, to denote a means of something.

Having previously encountered languages with an instrumental case, I can't help but draw similarities, and was wondering whether the ending could be employed thusly.

For example, would it be correct to translate 'Hans writes with a pen' as

Hans stiftisch schreibt.

?

I particularly choose this sentence as a relevant Wikipedia page instead provides

Hans schreibt mit einem Stifte.

as the appropriate translation.

For me this raises two questions:

1. Am I correct with my translation, or simply overzealous with my use of the -isch ending?

2. If my translation is accurate, how common is it for a native German speaker to also use the same approach?

Answer 1

First of all, I'd say the basic idea that in German, you can form adjectives ad-hoc by attaching a suffix is right. However, it doesn't quite work the way you outline.

Let's go through your question sequentially, also including some tangential remarks:

As is already explained in the post you found, there are several common suffixes that can be attached to form adjectives (-isch, -ig, -lich), and the resulting meaning is not always clear-cut.

For example, would it be correct to translate 'Hans writes with a pen' as: Hans stiftisch schreibt ?

Not really, and I don't really care that "stiftisch" cannot be found in a dictionary. First, word order should be different:

Hans schreibt stiftisch.

Even then, this somehow conveys to me that Hans is writing like a pen, not with a pen. As stated before, there is no fixed rule for the resulting meaning, but by default, I'd say it always leans toward something vague like "like X", "related to X", rather than in particular "using X".

I particularly choose this sentence as a relevant Wikipedia page instead provides: 'Hans schreibt mit einem Stifte' as the appropriate translation.

That sentence should read

Hans schreibt mit dem Stift.

The form "Stifte" is not just "not used in most common conversation", it is completely outdated both in spoken and written German.

Therefore: Adjectives are not usually created by native German speakers to express anything like the instrumental case, but they may occasionally be formed to express other things.

Answer 2

Well, the sentence

Hans stiftisch schreibt.

is completely wrong. No native speaker would even think of constructing such a sentence. Even worse: Nobody would understand it in the way you want it to be understood. It is wrong for two reasons:

1. There is no adjective "stiftisch". Even if you would use it grammatically correct (see next item), nobody would understand what you mean.
2. Adjectives which modify verbs always appear behind the verb:

wrong: Hans schön schreibt.
correct: Hans schreibt schön.

The sentence from Wikipedia

Hans schreibt mit einem Stifte.

is correct, but used an outdates dative ending. This is clearly mentioned in the Wikipedia article, but it sould be mentioned here too. This is correct in modern German:

Hans schreibt mit einem Stift.

---

But let's imagine the word »stiftisch« would exist, and you would use it correctly (after the verb). Even then it would be understood as:

Hans schreibt stiftisch.
Hans is writing like a pen.

So, if this construction was a case, it would be an equative case, not an instrumental case, although Proto-Indo-European didn't have an equative case but an instrumental case which became extinct in German about 1000 years ago.

The understanding of stiftisch used the same pattern as:

Hans schreibt türkisch.
Hans writes Turkish. = Hans writes like a Turk.
not: Hans writes with a Turk.