I am not a native speaker. On a previous question of mine, I thanked for an answer by saying:

So the phrase is not an idiom, since it is applied in its literal sense.

I consciously chose since over because, because — well, I like that usage of since, even though I know that some (native speakers) don't like it. Nonetheless, that choice got me thinking for a while, and it occurred to me that I even could have used more alternatives, namely as or for, without changing the meaning.

So, on a general note, here are the alternatives:

  1. Statement A (is true), because statement B (is true).
  2. Statement A (is true), since statement B (is true).
  3. Statement A (is true), as statement B (is true).
  4. Statement A (is true), for statement B (is true).

Are these completely interchangeable? Or interchangeable in certain situations? Or can you point out any (not-so-)subtle differences between any of them? Are there even more synonyms?


4 Answers 4


Here's my opinion of your alternatives.

  1. "because" is your best choice for clear, correct, unambiguous communication, especially if you want to be understood easily by other non-native speakers.

  2. "since" is acceptable, although it makes your statement ambiguous; the second meaning would be that statement A became true at the time that statement B became true. Example: "I study more often since I enrolled in class" conveys that when you enrolled in class, then you began studying more often. Rule of thumb: prefer "since" when your intent is to convey "from the time that".

  3. "as" is somewhat acceptable, but in your particular statement structure "as" has more useful meanings of "abstractly analogous" or "synchronously". Example: "I like apples as you like oranges" conveys that my liking is similar to your liking, i.e. equivalently strong/weak/notable/etc. Example: "I make dinner as you set the table" conveys that we do these tasks at the same time in the same place. Rule of thumb: prefer "as" when your intent is to convey "sameness".

  4. "for" can be acceptable, although I would never expect to hear it in normal conversation. It would come across as overly-academic, or possibly epic or religious. Example: "We eat well tonight, for tomorrow we go to war." Rule of thumb: prefer "for" when you want to be poetic and inspirational.

  • 6
    +1: excellently detailed answer! Though I would disagree that since makes the example ambiguous. “A is true since B is true” can’t be the temporal meaning of since, or at least not grammatically (though I’ve heard it used this way by non-native speakers); the tenses are wrong. The temporal sense here would normally be rendered as “A has been true since B became true”, or similar.
    – PLL
    Dec 18, 2010 at 19:36
  • 4
    You are conflating two usages of "as". There is another usage of "as" where it means more or less the same thing as "because". But since it could be easily confused, I think your usage note is still relevant.
    – siride
    Dec 30, 2010 at 19:10
  • Using 'as' does not denote occurrences happening in the same place. Example: 'I make dinner as you set the table.' One person could be making dinner at the same time as the other person sets a table in a different place. 'As' in this type of context refers to sameness of time but not necessarily of place. May 11, 2014 at 11:34
  • 3
    While reading "Sherlock Holmes" which is the first english book i read in the english language i noticed that the term "because" is hardly ever used. Instead the word "for" is used more often. This answer explains the difference well but i wonder if there is a historical preference of the word "for", or could the work of Doyle be described as poetic like you mentioned in #4 ?
    – Chris
    Nov 3, 2014 at 12:40
  • 1
    @Joel, You are conflating two usages of "since" too.
    – Pacerier
    Jun 3, 2016 at 6:07

From Longman contemporary dictionary:

BECAUSE (conjunction)

Used when giving the reason for something:

I went home because I was tired. The streets were flooded because of all the rain.

SINCE/as (conjunction)

Used when giving the reason why someone decides to do something or decides that something is true:

We decided to go to the beach since it was a nice day. I thought Kevin was out as his car wasn’t there.

DUE to/owing to (preposition)

Used to give the reason why something has happened. Due to and owing to are more formal than because:

The delay was due to a problem with the ship’s engines. The parade had to be cancelled owing to bad weather.

THROUGH (preposition)

Because of something. Through is used especially when saying why someone succeeded or failed to do something:

They won the game, more through luck than skill. You failed that test through carelessness.

THANKS to (preposition)

Used when explaining that something good has happened because of someone’s efforts, or because something exists:

Thanks to modern medicine, the disease can now be cured.

out of (preposition)

Because of a particular feeling or quality: He started reading the book out of curiosity. I only asked out of politeness.

  • 3
    Hmm, this does not explain the difference between "because" and "since/as". The explanations are the same, stating that they are giving reasons for something.
    – Pacerier
    Jun 3, 2016 at 6:10

I'd prefer 'because' or 'for' in most cases, although your usage of 'since' sounds just fine to me. Even though 'for' in this context might sound a bit old-fashioned, it's short and concise, so go ahead and use it! The more modern speakers use 'for', the less old-fashioned it gets.


What you are noticing is dialect differences. It really doesn't matter, and in our hyper connected media world, dialect differences mean less and less these days.

  • 1
    Which dialects?
    – jinawee
    Sep 3, 2014 at 19:42

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