Noun
(uncountable) Philosophy, especially traditional metaphysical philosophy, which makes claims that cannot be verified by everyday experience of the physical world or by a scientific method.
(countable) A particular philosophical school, system, or work representative of this kind of philosophy.
Source: en.wiktionary.orgI freely admit that the remembrance of David Hume was the very thing that many years ago first interrupted my dogmatic slumber and gave a completely different direction to my researches in the field of speculative philosophy. Immanuel Kant
Galen shared with Xenophon a scepticism of the value of books about most speculative philosophy, except for inquiries such as whether there is "something in the world superior in power and wisdom to man". Source: Internet
He devotes six books to philology, ten to speculative philosophy, and four to practical matters. Source: Internet