This thesis investigates the relation between logic and human deductive reasoning, as well as the issue of the significance of logic as a norm for the reasoning of which the natural language is an important medium. The main presupposition is that logic as a standard according to which humans ought to reason in order to reason correctly is not normative for thinking and reasoning. This is associated with a presupposition that normativity as a standard governed by a community can only be considered in a public sphere. There is an assumption that mother tongue influences reasoning and it is claimed that logic is learned in a similar way to learning a foreign language. It is also presupposed that knowledge of related disciplines such as mathematics or informatics can have a positive influence on reasoning, while logical competence may have a negative influence on the expressive power of language. Finally, the reasoning of people with mental disorders is investigated and it is shown that in some cases they follow rules of logic, but not the rules governed by their community. The thesis includes an overview of development of logic from Aristotle and Stoics to Frege and Łukasiewicz, logico-philosophical discussions given by Descartes, Wittgenstein, Harman and Field, psychological theories of reasoning (with the focus on theories of mental logic, mental models and dual theory), as well as linguistic theories of Chomsky and Dąbrowska. It is shown that there are sufficiently many arguments according to which it is possible to claim that the discussion of normativity of logic for reasoning has become redundant; that logic has its different applications, but they are connected to formal theories as logic itself is; that it is necessary to revise the usual definition of rationality; and, most importantly, that logic is learnable, but only a small group of people can learn it well, therefore, high quality and prompt education is required. The potential practical benefit of this work is a possibility of using obtained conclusions in the teaching of logic.