speculative philosophy
Noun
Meaning
(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.orgExamples
I 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.
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".
He devotes six books to philology, ten to speculative philosophy, and four to practical matters.