The philosophy of mind seeks to explain the nature of mental states and their relation to physical states. This MA thesis argues that neither classical dualistic nor modern physicalistic-reductionist explanations of this relationship are satisfactory. The aim of the thesis is to present the metaphysical theory of property dualism and its broader version called neutral monism, and to show how these theories offer an apt metaphysical framework for explaining mental states without giving up the ontological uniqueness and “causal closedness” of the world. The thesis begins with a brief historical account of the attempts at solving the mind-body problem: from Descartes’ version of dualism to modern eliminative materialism, together with their shortcomings. Subsequently, the ontological theory of property dualism is presented. In the third and longest part of the thesis, it is shown how the latter can be interpreted within a broader metaphysical framework called neutral monism, and how it applies to some standard issues in the philosophy of mind. The formulations of the two philosophical theories, together with their main statements and arguments, are for the most part taken from the texts of John Heil and, to a lesser degree, of David Chalmers. Heil’s ontology of properties presupposes that every property has a dual nature: it is both qualitative, such that it somehow „looks like“ (for its bearer) to have the property, and dispositional, such that it enables specific physical reactions (under relevant conditions). In Heil’s account, these two types of properties are inseparable as two sides of the same coin: the same fundamental properties that determine our behavior necessarily determine our conscious (mental) life – the intrinsic (subjective) character of our mental states. In final part of the paper it is shown how this version of monism (property dualism) contributes to our understanding of certain peculiar features of mental states: privileged approach to these states by their subjects or bearers, their intentionality (“directedness” towards their objects), apparent indiscernibility of their own (intrinsic) properties from the properties of their intentional objects, and the ability of such states to mentally present their intentional objects (“mental imagery”).