Awareness of boundary issues and scope of analysis is essential in critical thinking.
Let’s take a look at energy. We tend to bucket energy sources in buckets like renewable, fossil fuels and nuclear, but what does that really mean?
On the face of it fossil fuels and energy sources like solar, wind and hydro have nothing in common and are seem contradictory. Solar energy obviously is energy captured from the sun and as wind is also a phenomena caused by solar heat it too is a solar derivative. With respect to hydro, the sun heats water which, with the help of wind evaporates, forms clouds and then rains down in mountains where we can use the water to run turbines and capture kinetic energy. Therefore hydro is also a solar derivative.
Fossil fuels are the product of organic remnants of primarily plants which lived a long time ago, died and were transformed under heat and pressure into various forms of fuels like coal, oil and natural gas. Those source plants however were powered by the sun, so as we zoom out fossil fuels too are a form of solar energy.
That leaves us with nuclear as a true separate and distinct energy source. Or is it?
The sun is a ball of gas which is so large that the particles on the inside are squeezed together to the point where they fuse. In other words, a nuclear (fusion) reaction. The sun then is a form of nuclear energy.
That leaves us to the inevitable conclusion that at the macro-most level all energy sources that we have access to and are aware of are nuclear at their core. So when we talk about renewables, fossil fuels etcetera keep in mind that these are distinctions which exist only because of a choice in the scope of analysis.