The classical problem of universals asks: when many individuals share a common name, this horse, that horse, the horse you rode last year, what exactly does the name refer to? Is there one universal horseness that all horses participate in? Or just a useful mental habit of grouping similar things? Ibn Sina's answer is a carefully balanced middle position, often called moderate realism.
Universals, he argues, exist in three modes: before the many (in the divine intellect as archetypes), in the many (as the shared nature instantiated in individuals), and after the many (as the concept abstracted by the human mind). The word "horse" in human language corresponds primarily to the third mode, the abstracted concept, but that concept tracks something genuinely there in the second mode, and ultimately anchored in the first.
This three-fold structure does real philosophical work. It explains why science is possible: when we discover the essence of heat or of living things, we are not merely cataloguing our own mental habits but uncovering what is in the things themselves. It explains why communication is reliable: my concept and yours are both formed by abstraction from the same essences in things. And it explains why language can mislead: if a word drifts from its essence, through metaphor, convention, or political manipulation, thought untethers from reality.
Ibn Sina's Logic opens al-Shifā' precisely because he believed correct language use is the gateway to all genuine knowledge. A badly defined term produces a faulty syllogism; a faulty syllogism produces false beliefs about nature, ethics, and God. Language hygiene is not pedantry, it is the foundation of the entire intellectual edifice.
He also discusses poetic language, showing genuine philosophical curiosity about imagination and rhetoric. Poetic utterances are not simply false assertions; they work through imaginative assent, creating vivid representations that move the soul even without strict truth-claims. Beauty in poetic language has, he argues, genuine moral value: it can orient the soul toward the good even when it cannot provide a logical proof. This makes Ibn Sina's philosophy of language surprisingly broad, covering not just science and theology but also art, persuasion, and the affective life of the mind.
A concrete example: in translating Greek philosophical vocabulary into Arabic, Ibn Sina and his predecessors faced a language that had rich resources for poetry and theology but lacked technical philosophical terms. Words like jawhar (substance) had Qur'anic resonances that clashed with Aristotelian usage. Ibn Sina's solution was systematic definition, anchoring each word to a precise essence, while acknowledging that natural language always carries more meaning than technical usage can control. He was, in a phrase, doing philosophy of language in the act of doing philosophy.