Originally Posted by
Mingle
I would say that Maltese is separate from Arabic in the same way that Standard Italian is separate from Latin. Standard Italian is derived from a dialect of Vulgar Latin, but its considered a distinct language from Latin due to the low level of mutual intelligibility between Latin and Italian. Similarly, Maltese is derived from a regional dialect of Classical Arabic, but its low level of mutual intelligibility makes it a different language. In short, its "Arabish", but not proper Arabic.
Although the same could technically be said for some Arabic dialects like Tunisian (closest dialect to Maltese), so its partly a question of politics. The reason why Maltese is usually considered a separate language from Arabic though is because Maltese has its own standardized register whereas other dialects descended from Classical Arabic are considered crude forms of Standard Arabic as opposed to given their own official status or standardization and the line has to be drawn somewhere. In a way, its not really wrong to call it Arabic, but its different enough from Standard Arabic to be called a separate language.