Other forms: rationalities
Use the noun rationality to refer to the state of being sensible or having good judgment. People may question your rationality if you insist on jumping into freezing water in January and skydiving for the rest of the year.
The noun rationality also means the state of being agreeable to reason or being based on logic. If you have to pick a pre-school for your child, you should base your decision on rationality and not an illogical reaction, such as how many of the kids eventually go to Ivy League universities. The newer school may look better on the surface, but the older building may have better teachers, a more interesting curriculum, and be closer to your home.