Learn English – “Ironic” vs. “ironical”

The Corpus of Contemporary American English shows 4253 occurrences of “ironic” and 134 occurrences of “ironical”, that is 32 to 1. The British National Corpus shows 703 and 88, respectively, that is 8 to 1. These results support the feeling that “ironical” is less common than “ironic,” but they do not suggest that the word “ironical” is a feature of American English.

The Oxford English Dictionary (OED) does not state any regional preference of the word “ironic” or “ironical” (the links require subscription). Interestingly, the definition of “ironic” in the OED is just:

Pertaining to irony; uttering or given to irony; of the nature of or containing irony; = IRONICAL.

and detailed definitions are given for “ironical.”

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.