Many words or phrases can be used to set up an explanation. The most common is because (or “because of”), but others have their uses. Here are alternatives and a discussion of their uses and their merits.
1. As: As is a direct synonym for because (for example, “He opted not to go see the movie, as it had gotten poor reviews”), but it’s inferior.
2. As a result of: This phrase is a substitute for “because of,” not because, as in “As a result of his intervention, the case was reopened and they were ultimately exonerated.”
3. As long as: This informal equivalent of because is used to express the thought that given that one thing is occurring or will occur or is true, another is possible, in such statements as “As long as you’re going, could you pick some things up for me?”
4. Being as (or being as how or being that): This phrase has the same sense — and the same formality — as “as long as.”
5. Considering that: This phrase is essentially identical in meaning to “as long as” and “being as” and its variants.
6. Due to: Like “as a result of,” “due to” is a preposition, rather than a conjunction like because, and is used in place not of because alone but instead of “because of.” It applies specifically to an explanation of why something occurred or will or will not occur, as in “Due to the large number of applications, we cannot respond individually to each applicant.”
7. For: This substitute for because is reserved for poetic usage, as in “Let us eat and drink, for tomorrow we die.”
8. Inasmuch as: This phrase is a very formal equivalent of because, as in “Inasmuch as his account has been discredited, I wouldn’t believe anything else he says.”
9. In view of the fact that: This phrase is identical in sense to “inasmuch as.”
10. Now that: This phrase informally connotes cause and effect, as in “Now that you’re here, we can proceed.”
11. Out of: This phrase applies to explanations of emotion or feeling — for example, “She asked out of compassion” or “Out of spite, I refrained from passing the message along.”
12. Owing to: This phrase is equivalent to “due to”; the two choices are more formal than “because of.”
13. Seeing that: This phrase is identical to “considering that.”
14. Since: This alternative to because is informal and is considered inferior because since primarily refers to elapsed time and the usage might be confused, as in “Since it had rained, we didn’t need to water the garden”; the reader might not realize until reading the second half of the sentence that the sense is causal rather than temporal.
15. Thanks to: This equivalent of “because of,” despite the wording, can apply to either a positive or a negative outcome; “Thanks to your meddling, we’re receiving much unwanted attention” demonstrates the latter sense.
16. Through: Through is a preposition; it takes the place of “because of,” as in “Through the efforts of these charities, the city’s homeless services have been reinstated.”