In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Question to Shaikh Rabee [hafidhahullaah]: May Allaah reward you with good; this is also a question from the brothers who are present, saying: Assalaamu Alaykum Warahmatullaahi wabarakaatuhu. Virtuous Shaikh, is it permissible for me to learn [or study] the knowledge of philosophical logic? Benefit me [i.e. with a response] and may Allaah [The Exalted] reward you with good.
Answer: The knowledge of philosophical logic is a corrupt knowledge and the Salaf- by way of consensus- declared that it is Haraam [forbidden] to study it due to the misguidance and disgustingly evil consequences within it. Shaikhul Islam Ibn Taymiyyah [rahimahullaah] said, “Neither does a dull-witted person benefit from it nor is an intelligent person in need of it”. An intelligent person is not in need of it because he is sensible in his self, natural disposition and intellect; and a dull-witted person does not benefit from it. Even if he studied all the books of philosophical logic, he will not benefit from it.
Shaikh Albaani [rahimahullaah] used to debate against the scholars of philosophical logic and they used to be like children in his presence, yet he never studied philosophical logic; rather Allaah granted him [sound] speech and [Sharee’ah] knowledge, and there is no proof stronger than the proofs of the Kitaab [i.e. the Qur’aan] and the [authentic] Sunnah.
The people of philosophical logic are always defeated [or overwhelmed]. By Allaah, regardless how much they [utilise] philosophical speech and how strong they are in philosophical logic, they are defeated [or overwhelmed] in the presence of the methodology of the Salafus Saaleh [which is] founded on the Book [i.e. the Qur’aan] and the [authentic] Sunnah.
[Source: An Excerpt from Marhaban Yaa Taalibal Ilm page 347. Slightly paraphrased]