Rationality is also not the opposite of emotionality. You don’t have to be Spock to be rational.
An example: I am a rational people, I will pick certain portion of reality that allow me to construct a good model of myself, with blind eyes for the part I don't want to see.
You can use "rational thinking" to construct rationalization of your behaviour.
Since there is no logical notion of justice, rational thinking and rationalization are not far away.
If you're excluding data points because they lead you away from your desired conclusion, then you're not thinking rationally, you're rationalizing.