In 1989, he was conferred Habilitation, a German post-doctoral qualification from the Philosophy Department of Ludwig Maximilian University of Munich.

Currently, he is speaker of the executive study program Philosophy, Politics, and Ethics (PPE) and member of board of the Parmenides Foundation that supports multi-disciplinary research between the natural sciences and humanities.

He is part of the panel Finance and Ethics of the German Association of Financial Analyst and Asset Managers (DFAV e.V.)

His article, "The Case for a Change of Course in European Policy", co-authored with Peter Bofinger and Jürgen Habermas, was translated and published in 12 languages.

[citation needed] Nida-Rümelin propounds an approach to practical philosophy based on his theory of "Structural Rationality".

The intimate connection between morality and rationality that Kant postulates becomes one aspect of the broader, all-encompassing account of acting in such a way that fits into a desirable structure of agency.

In this way, the account of structural rationality avoids the dichotomy of reasons – moral versus extra-moral – and allows us to make use of the conceptual frame of decision and game theory in order to clarify some essential aspects of practical coherence.

The term “utility” is misleading and should be replaced by “subjective valuation.” The deontological character of structural rationality is compatible with using the conceptual framework of decision theory.

[citation needed] Drawing on these considerations, Nida-Rümelin deals with the relationship between philosophy and Lebenswelt (life-world)/ Lebensform (form of life).

Taking this as a starting point any incoherences can be criticized and are the impetus for philosophy in general, and for ethical theory more specifically.

Philosophical theory has to be careful not to leave the common ground of the human practice of giving and taking reasons.

Humanists think that the ability to act and believe and feel based on reasons is essential in order to understand the human condition.

Those who take anthropological humanism seriously tend to embrace a humanistic ethos and those who reject humanistic principles of agency tend to fight against anthropological humanism, expressed in different forms: social Darwinism, racism, reductionist naturalism, chauvinist nationalism, discriminating sexism and other forms of anti-humanism.

Since communication plays a central role in this form of humanism, Nida-Rümelin presented an account of humanistic semantics.

Nida-Rümelin embraces insights of Alonzo Church and Kurt Gödel from the 1930s regarding non-computability showing that reasoning cannot be exclusively algorithmic.

[9] Nida-Rümelin spent five years (1998–2002) in politics, first as head of the municipal department of arts and culture in Munich, the capital of Bavaria.

He then held a ministerial office as the State Minister for Culture and Media and was a member of the national government of Chancellor Gerhard Schröder.