Recently the Pournelle Chart was analyzed. It has both its advantages and disadvantages when compared to the Nolan Chart, but overall is a good way to represent the political spectrum.
That leads to the question of what the result would be if the two charts were combined. Given that the liberty axis of the Pournelle Chart is basically the vertical cross axis of the Nolan Chart, it would simply be a matter of substituting the one axis with the two axes to create a cube. The three axes would be Economic Liberty, Civil Liberty, and Rationality.
To view it directly on the Rationality axis it would look exactly like the Nolan Chart, which means that the only thing to describe is the high and low rationality end of each of the four corners.
Starting with the corner of high economic liberty and high civil liberty, the high rationality aspect is libertarianism, including anarcho-capitalism and objectivism. The low rationality aspect is counter-cultural anarchism.
In the corner of high economic liberty and low civil liberty, the high rationality aspect should be considered conservatism excepting the fact that conservatives do not embrace economic liberty. Either the theoretical model needs a new name, or the modern conservative needs to embrace a new name. A low rationality equivalent would be the Theocrat. The difference is that one is the security conservative and the other the moral conservative. The theocrat, the moral conservative, is technically an authoritarian but as Ayn Rand pointed out they consider economics to be less important than civil matters and are willing to not regulate it because other matters are more important.
In the corner of low economic liberty and high civil liberty, the high rationality aspect is the welfare liberal. These are the ones that support welfare due to the belief that government can solve economic problems. Their low rationality counterpart is the libertine who relies on government to support. There is no overarching philosophy behind this position other than a feeling of entitlement.
In the final corner of statism, the high rationality aspect is communism, in which there is a belief in government planning of all aspect of society, while the low rationality aspect is fascism.
Perhaps there could be further refinements, especially further examination how to effectively measure the rationality axis, but this could also be considered a more descriptive model than either of the parent models when considered alone.