Philosophy means the love of knowledge. Its source is rooted in doubt, in basic questions relating to human existence. Judaism has its basis in the Revelation at Sinai, in the Written and Oral Law. Over the centuries Judaism has grappled with these questions by means of interpretation and exposition - found in the Talmud and Midrash and the like. Religious Jews believe that greater certainty attaches to what we have learned from G-d than to anything that we could learn from man alone.
Philosophy attempts to find solutions by means of human reason.
Historically, the Tenach does use arguments based on human experience in dealing with certain issues, e.g. in the books of Job and Ecclesiastes. In a spiritual seclusion, Judaism relied on finding its own solutions. BCE, mainly in Alexandria, it developed a philosophic system. As Islam spread from the 7th century CE onwards, it came into contact with the Greek systems of thought, Aristotle, Plato, Neo-platonism and so on. After Saadia, the centre for Jewish Philosophy was Spain, with the same favourable milieu of Islam, and later to Provence and Christian Spain.