Final answer:
The general capacity for thought in humans must be shaped through education and self-development. This molding process involves cognitive development, critical reflection, and the acquisition of rationality and moral understanding as key components in refining an individual's capacity for abstract and ethical thinking.
Step-by-step explanation:
People possess only a general capacity for thought. This capacity must be shaped and refined in the process of education and self-development, which involves gaining knowledge, experience, and wisdom through various stages of life. It is in the act of engaging with ideas and challenging one's beliefs that one's capacity for critical and reflective thinking is honed.
During adolescence, according to cognitive development theories, there is an increase in processing speed and efficiency, which contributes to the emergence of more complex thinking abilities. This is a time when individuals move beyond concrete thinking to abstract thought, possibly reflecting changes in mental capacity.
Moreover, through the discipline of Philosophy and other avenues of learning, individuals reflect on their thinking, examining the beliefs and assumptions that shape their worldview. Engaging in critical reflection and metacognition—thinking about thinking—people can cultivate their capacity for rationality, moral inquiry, and ethical thinking, which in turn shapes their personalities and virtues.