Why do scholars debate the position of Arabic within the Semitic language family?

Scholars debate the classification of Arabic within the Semitic languages because it exhibits conflicting linguistic features that align with different branches of the family.1

The debate centers on whether Arabic should be grouped with the Northwest Semitic languages or the South Semitic groups. The primary arguments include:1

• Central Semitic Theory: Many researchers classify Arabic as part of a "Central Semitic" branch alongside Northwest Semitic languages (such as Aramaic and Canaanite). This is supported by similarities in their verbal inflection systems, which are viewed as shared innovations.12
• South Semitic Affinities: Conversely, in its sound system and word-formation processes, Arabic appears more closely related to Ethiopic and Modern South Arabian languages. Some scholars point to the development of the f sound from the early Semitic p as evidence for a distinct South Semitic grouping that includes Arabic.1

Because determining whether these shared traits are "innovations" (which suggest a closer genetic link) or "archaisms" (inherited traits) is difficult, the exact position of Arabic remains a subject of ongoing linguistic analysis.1