Mentality is rationality. Rationality pertains to ratios. Ratios are about relationships and proportions. Mentality, mind, intellect, reason, rationality - all these terms describe the ability to reason: to recognise proportions, relationships, correlations and ratios in the world.
It is remarkable that the word 'rationality' contains the word 'ratio'. Ratio is about a relation between things, and that's what mentality is about:
The ability to recognise relations, patterns, connections and contexts.
Mentality (intellect, mind, reason) is an inner structure that puts all information from the outside world into a context. That's how comprehension arises. If you can't designate a thing into its correct place, you will either not comprehend it or you will misunderstand it. All loose facts are useless unless they are understood in their correct relation to other things.
This 'putting-into-relation-to-other-things' is what constitutes actual thinking and the faculty of reasoning. All rational concepts and correctly understood facts have a relative meaning in their own contexts. Everything is interconnected and integrated, because reality is an interconnected and integrated whole. And it is the task of mentality to render that reality accurately. The level of accuracy with which the mind can mirror reality is an indication of the stage of development of the mental faculties.
It's important to cultivate mentality, so that emotionality is kept in check and rationality is prioritised when making decisions.
Mentality vs. Emotion
Emotionality doesn't recognise proportions. In its pure form as arousal or excitement emotion loses itself in impulsivity and lacks any restraints. When emotionality prevails at the cost of the intellect, then the result is a lack of judgment, excitability and a tendency to superficial and inaccurate conclusions. When reason prevails, then the result is a better sense of judgment, because the mind can recognise nuances and put information into a correct context.
Everything we know about ourselves and the world is the result of perception. Perception is a mix of two faculties: the senses gathering information from the environment and the comprehension of that information by mentality.
Development of Thought
The goal of mental development is to create an inner mental structure that fully accords with reality. Such a mental structure would be an interconnected network of thoughts explaining reality.
Ethics for Mentality
When mentality is used to think about issues and draw conclusions, rational motive becomes the motivation for decisions. ‘Mental’ ethics is about having the intellectual freedom and access to information so that science and knowledge can flourish.