Theory is at the heart of science. Scientists come up with theories, test them, confirm them, falsify them, derive them from observation, theories are one of the staples of science. Hence scientists love discussing theories. Within the following lines, I want to show you a conceptualisation of different levels of theory, building on examples from sustainability science. When reading a book about inequalities, I was at some point getting the feeling that this different forms of inequalities were like an enumeration to me. While each and every one of these inequality had a clear footing in reality, they felt more like examples of inequality. What was lacking to me was a more general level about inequality. Instead it seemed more like a composite of inequalities. Hence I derived a system of levels within theory, which I will present here. 1) The highest levels of theory are concepts. These represent theoretical thinking that does not contain smaller parts of theoretical thinking. Reason, logic, justice and peace are examples of such thinking. Philosophy is most relevant for this level of theory, and it is most relevant to generalisable knowledge. 2) The second level I call paradigms. Paradigms are composites or connections of several concepts. Sustainability can be an example for this, as some people define it as a composite of equality, livelihoods, resources and other things. Gender equality is another example, which consists of two combined concepts. You may talk about this for decades, but if you have a different definitions about gender, your discussion will never end. Paradigms make concepts graspable. Not everybody is a Philosopher, but paradigms are the large narratives of our culture. More tangible , yet with enough blurriness to keep you thinking. 3) Level 3 I call framework. These pave the road to connect paradigms to the real world. The sustainability development goals are an example, or the Ostrom framework. Frameworks imply causality or have the explicit focus to make paradigms applicable in planing and management. Hence framework link science to the real world. Level 4 are cases. Cases are simply the bread and butter of empirical work, allowing us to apply frameworks. The last level are then actors in cases. These are the lowest level, where theory is ultimately understood – or not understood. Now many discussions you see and hear start on one level. You have the occasional discussion about sustainability. Somebody says: „to me it is about justice“, so you go one level up. Then suddenly somebody said „but what about the vegan Amish“, and you go down quite some levels. The nestedness of the vegan Amish can be linked to upper levels, but ultimately this is blur, and they are just composites of paradigms. All world religions resolve around paradigms. Take the trinity or the four noble truths. These then connect down, for instance through the Ten Commandments or the noble eightfold path. Within science, it is quite good to understand where you have the strongest footing. Few are philosophers, many work with the conceptual linkages of paradigms, and even more utilise the applied power of frameworks. It is good to locate not only yourself, but also the level on which a discussion is running, or jumping. Levels 2 and 3 often get taxed by a lack of any clarity on the first level. Only by verbalising these problems, we shall be able to move our conceptual thinking forward to this end. Let’s do it!