Well, this sounds familiar:
William of Ockham
Ockham is the founder of nominalism in the so-called “modern school” – via moderna. Science has to do, he maintains, only with propositions, not with things as such, since the object of science is not what is but what is known. Science deals with general concepts which, as such, exist only in the human mind. Ockham’s epistemology thus antedates logical positivism, to the extent of claiming that science is only supposed to and can no more than describe the content of perceptions in a formal way.
Ockham rejects the idea of moderate realism that universals are something in particulars which is distinguished from them not realiter but only formaliter. He considers the universal as an intention of the mind, a symbol representing several objects, but being numerically one and an individual mental representation.
External objects call forth sense-impressions in us, which are transmuted by the active intellect into mental images. These images are a product of the active intellect, not species which flow from the object into the potential intellect. The reality of these images is thus, in the modern use of the terms, not objective but subjective. The result of this line of reasoning is the absolute subjectivity of all concepts and universals, and the limitation of knowledge to the mind and its concepts – although these are real entities because of their subjective existence in the mind.