word choice - What is the difference between ですから, だから, それで、 それでは？

I think they have the same meaning: therefore.

But my teacher told me they were slightly different.

So can you help me distinguish them and how to use please?

Answer

Let's look at some examples:

[彼女]{かのじょ}はめっちゃかわいい。(だから/それで)[男性]{だんせい}に[人気]{にんき}がある。

In the above post, I think you could use either だから or それで. So in some situations they are interchangeable. However, I think the underlying meaning is slightly different. When you use だから, it puts a strong emphasis on the reason why, also it has more of a tendency to be a result of personal opinion. On the other hand, それで can be thought of as "naturally forming" from the reason. Let's try to translate the above sentences which show the difference:

(だから)The reason (I think) she is popular with guys is because she is so cute.

(それで)She is so cute. That's why (it naturally follows that) she is popular with guys.

In my first translation, I emphasized The because だから puts an emphasis on the reason why. Also, I put "I think" in parentheses because だから can also imply that it is your opinion. As for それで, I put "it naturally follows that" in parentheses because it can imply that. However, I should mention that these nuances are much more subtle than how I expressed them.

もう[時間]{じかん}がないんだ。(○だから/×それで)急ごう。

ここは[危]{あぶ}ない。(○だから/×それで)入ってはいけない。

In the above sentences, それで cannot be used. The reason why is because the それで cannot be used with expressions that are commands or put a strong emphasis on the reason why. So, from this, we can infer that だから has a much more broader meaning than それで. However, even though だから has a broader meaning, you may hear それで more often because in Japanese culture people tend to avoid expressions that put a strong emphasis on one's own opinion, etc. (your mileage may vary though).

As for the differences between ですから and だから, です is just a more polite form than だ. However, それで and それでは have completely different meanings. You use それでは (and the more colloquial それじゃ) for the following:

1. 
   

   Saying goodbye:

   
   
   

   
   

   それではお元気で

   
   

   
   


2. 
   

   Expressing a decision or opinion based usually on something previously mentioned by the person you are talking to:

   
   

   
   

   Aさん：[風邪]{かぜ}[引]{ひ}いちゃった。Bさん：それじゃいけないね。

   
   

   
   



3. 
   

   When beginning or ending something (like a meeting or something).

   
   

   
   

   それでは始めます。

   
   

   
   

(This list is not exhaustive.)