で: 責任者で

[TheUnitedStatesOfEurope]

Hi everyone、皆さんこんにちは。

I wrote the sentence below, but a Japanese friend told me that instead of と, で should be used.
The context of the email is formal / polite.

私は研究開発プロジェクト責任者[と or で ] プラズマCVDの専門家です。
I am R&D project manager and expert in plasma CVD (plasma-enhanced chemical vapor deposition, PECVD).

May someone tell me what would be the difference please?
Is と better for enumerations: eggs と meat と bread と milk... And で better for juxtaposition?: entrepreneur で woman / chemist で physicist / husband で confident?
Or is で more formal and polite than と ? Or is で better for a professional / business context?
Anyhow, I'm just spitballing here.

Could a native please explain me why で is prefered here?
Thank you so much for your precious help.

Thank you so much | どうもありがとうございます m(_ _)m
The USE | ヨーロッパ合衆国

 

[Joschl]

私は研究開発プロジェクト責任者で(,)プラズマCVDの専門家です。
"de" here is the adverbial form (te-form) of the essive copula "da", which is a part of the predicate of the first clause. We need to use the adverbial form "de" to connect two clauses without a conjunction connecting two clauses (i.e. [X wa Y da.] + [X wa Z da.] -> [X wa Y de, (X wa) Z da.]) The particle/postposition "to" connects nouns within a phrase ([X] to [Y] to [Z] to...)

で （助動） 断定の助動詞「だ」の連用形。連用中止法に用い，[...]。 〔古語の断定の助動詞「なり」の連用形「に」に助詞「て」の付いた「にて」の転。中古末から中世へかけての成立〕 →だ（助動）https://sakura-paris.org/dict/大辞林/prefix/で

１ 「と」は助詞です。複数の名詞をつなぎます。
３　文と文をつなぐときに、「と」ではつなげません。文と文をつなぐときは、[...]動詞の「て形」などを使います。日本語 文法 02.25.1 NとN：解説

 

[SoLaTiDoberman]

Eggs and meat (卵と肉）are two different things. In this case, the "and" is translated as と in Japanese.

I'm a mother and professor： In this case, the mother and the professor are not two different people, but only one person, "me (I)."
In this case, the "and" is translated as で in Japanese: 私は、母親で教授です。

I am an R&D project manager and expert in plasma CVD.
=私は研究開発プロジェクト責任者でプラズマCVDの専門家です。
=私は研究開発プロジェクト責任者であり、プラズマCVDの専門家です。
=私は研究開発プロジェクト責任者であると同時にプラズマCVDの専門家でもあります。
=I am an R&D project manager and also an expert in plasma CVD.
=I am an R&D project manager and at the same time, I'm an expert in plasma CVD.

cf) 私は私は研究開発プロジェクト責任者とプラズマCVDの専門家にメールを送った。(２人に送った）
＝I sent an email to an R&D project manager and an expert in plasma CVD.

There is no difference in politeness between で and と.

> entrepreneur で woman
> chemist で physicist
> husband で confident

Is it clear?

According to modern cutting-edge technology, artificial meat can be made from vegetables for vegetarians.
Maybe it is possible to make the artificial meat from eggs.
In that case, we can say "The cooking ingredient is both eggs and meat at the same time!": その食材は、卵で肉です。（笑）

 

[Joschl]

The clauses that are connected by means of the te-form of the essive copula can have the same subject as in "私は研究開発プロジェクト責任者でプラズマCVDの専門家です" above. The subject of the second clause "([Xは])プラズマCVDの専門家です" can be considered to be omitted. Because the inflected copula "de" connects clauses with each other, the subjects of the clauses can also be different as in [Xさん]は[predicate noun1]で，[Yさん]は[predicate noun2]だ. The particle/postposition "to" doesn't work here because "to" cannot connect clauses as a verb can.