The classical scholars did not prohibit philosophy as we understand the term in the contemporary sense.
The Shaykh al-Azhar, Hasan al-Attar (d.1835 CE), whilst writing on Sujai's treatise on the Categories, provides one of the best explanations:
If you seek to understand what exactly is being disputed, then heed what is being said to you: the position that states all philosophy [hikma] is impermissible is an exaggeration, and that is because philosophy divides into two primary areas: theoretical and practical.
Practical philosophy then subdivides into household economics, politics, and ethics; and these three subjects were not given any importance in Islamic scholarship, as each of these pertains to practical life and shari'a has rendered them redundant.
As for theoretical philosophy, it also has three divisions: metaphysics (ilahiyat), mathematics (riyadiyat), and natural philosophy (tabi'iyat). Likewise, each one of these divisions has questions which are fundamental or primary, and others which are secondary or derivative.
Under mathematics fall the subjects of arithmetic and all its branches, and geometry, etc., and what rational person would say such subjects are prohibited knowing many shari'a laws are obviously dependent on them?
As for natural philosophy, it includes medicine and surgery, which are two of the most important and beneficial sciences none can dispense with, so all othese sciences are furud kifaaya…
Metaphysics is problematic as it is the source of heresies; even then, to claim it is forbidden is also mistaken, as the truth is more nuanced.
Ruling on Studying Philosophy
If the person is knowledgable of Qur'an and Sunnah, is intelligent, and seeks through study to respond to objections and refute claims of heretics, then this is something no one prohibits, likely a communal obligation.
The reasoning that the science of poetic metre (arudh) is a communal obligation because of the necessity to distinguish between miraculous speech is similar.
This is how the study of falsafa is understood when it was undertaken by early scholars like Fakhr al-din al-Razi and al-Ghazali, and many others.
As for those with no understanding of the Islamic sciences to help navigate arguments, doubts and objections, then such studies are not permitted.
This is how Sunni scholarship understood "falsafa," clear to anyone versed in the tradition. Peripatetic philosophy is divided into the theoretical and the practical.
Practical philosophy was not important, because the shari'a has its own sciences that deal with that: namely fiqh, usul al-fiqh, tasawwuf and kalam.
The problematic divisions were part of their theoretical philosophy, which included physics and metaphysics.
Nevertheless, its study as a communal obligation to respond to it and enrich the kalam tradition, which studied both epistemology and metaphysics, but from a revelatory perspective.
Thus the kalam tradition is philosophy as well, but in the general sense of the term, not in the specific sense captured by the terms hikma or falsafa in traditional nomenclature.
Kalam was led by the Sunni schools of Ash'arism and Maturidism, and are contrasted against falsafa. This rivalry is best captured by Sa'd al-Din Mas'ud b. Umar al-Taftazani, one of the greatest scholars in Islam, in his major work on kalam, Sharh al-Maqasid:
For just as the philosophers [al-ḥukama] wrote books in practical and theoretical philosophy [ḥikma] to guide the laity towards the two dimensions of human perfection, the scholars of the Islamic community, wrote books in kalam, fiqh and usul fiqh. So kalam is juxtaposed against theoretical philosophy [al-ḥikma al-nadhariyya].
Since kalam and philosophy performed the same functions, they were by definition in competition with one another.
There was never a problem with philosophy in the general sense, but with a specific set of metaphysical positions. One of the most central of these questions was the understanding of God: is he a free creative agent (fa'il mukhtar) or a being who necessarily creates, such that he has no will? What is the nature of causation? Is the world eternal or created ex-nihilo? How do we explain the relationship between God and the World? It was the answers provided by the peripatetic tradition that disturbed the kalam tradition, and not the fact that they exercised rational investigations into these questions.
The relationship between philosophy and kalam is that they are two mutually independent schools of thought, that both seek to arrive at truth using rational methods. It is not the case that philosophy is 'the honored servant of theology,' as some claim. It was not a training in philosophy Muslim scholars felt was necessary to sharpen the intellect, it was instead an education in the discipline of logic, argumentation, the linguistic sciences, and above all: kalam.
The Maydan, Abdullah Mihiring, The Myth of Intellectual Devline2017 https://www.themaydan.com/2017/11/myth-intellectual-decline-response-shaykh-hamza-yusuf/#.XOAa81cUeKg.facebook
Great answers start with great insights. Content becomes intriguing when it is voted up or down - ensuring the best answers are always at the top.
Questions are answered by people with a deep interest in the subject. People from around the world review questions, post answers and add comments.
Be part of and influence the most important global discussion that is defining our generation and generations to come