section_path: Arabic–Persian/Later classical
section_name: Later classical
paragraph_text: Later classical
  
  Avicenna (980–1037) drew on the philosophies of the Ancient Greeks and Al-Farabi to develop a comprehensive philosophical system aimed at providing a holistic and rational understanding of reality that encompasses science, religion, and mysticism. He regarded logic as the foundation of rational inquiry. In the field of metaphysics, Avicenna argued that substances can exist independently, while accidents always depend on something else to exist. For example, color is an accident that requires a body to manifest. Avicenna distinguished between two forms of existence: contingent existence and necessary existence. He posited that God has necessary existence, meaning that God's existence is inherent and not dependent on anything else. In contrast, everything else in the world is contingent, meaning that it was caused by God and depends on Him for its existence. In psychology, Avicenna viewed souls as substances that give life to beings. He categorized souls into different levels: plants possess the simplest form of souls, while the souls of animals and humans have additional faculties, such as the ability to move, sense, and think rationally. In ethics, Avicenna advocated for the pursuit of moral perfection, which can be achieved by adhering to the teachings of the Quran. His philosophical system profoundly influenced both Islamic and Western philosophy.
  
  Al-Ghazali (1058–1111) was highly critical of Avicenna's rationalist approach and his adoption of Greek philosophy. He was skeptical of reason's ability to arrive at a true understanding of reality, God, and religion. Al-Ghazali viewed the philosophy of other Islamic philosophers as problematic, describing it as an illness. In his influential work, The Incoherence of the Philosophers, he argued that many philosophical teachings were riddled with contradictions and incompatible with Islamic faith. However, Al-Ghazali did not completely reject philosophy; he acknowledged its value but believed it should be subordinate to a form of mystical intuition. This intuition, according to Al-Ghazali, relied on direct personal experience and spiritual insight, which he considered essential for attaining a deeper understanding of reality.
  
  Averroes (1126–1198) rejected Al-Ghazali's skeptical outlook and sought to demonstrate the harmony between the philosophical pursuit of knowledge and the spiritual dimensions of faith. Averroes' philosophy was heavily influenced by Aristotle, and he frequently criticized Avicenna for diverging too much from Aristotle's teachings. In the field of psychology, Averroes proposed that there is only one universal intellect shared by all humans. Although Averroes' work did not have a significant impact on subsequent Islamic scholarship, it had a considerable influence on European philosophy.