The article considers the problem of the division of economics into positive and normative, as well as its reinterpretation due to the assumptions of the theory of deterministic chaos for economic phenomena and the functioning of the market. The research question is expressed as a doubt whether adopting idealistic postulates and the related value judgments in economics is anyway justified or useful if the phenomena under discussion turned out to be purely chaotic. The issue of the subject of investment activity was raised, paying attention to the historical outline of the constitution of the basic economic categories relevant to the economics of investment. The subject of the considerations was subordinated to the assumptions of the complexity economics and the theory of deterministic chaos, with some of their properties presented as arguments for the legitimacy of applying them to research on financial markets and the economic system. After introducing the classical division of economics into positive and normative, attention was drawn to the specific interpretation of this division in terms of the chaos theory. The legitimacy of this division was checked, while it was found that the high degree of uncertainty of the results in the chaotic dynamics limits the judgments absolutely sure, and therefore a greater importance should be given to the normative approach. The considerations have been extended by several observations pointing to open issues and postulates of reasearch procedures within the complexity economics applicable for investment decisions.