A principled person is one with morals, who follows those morals.
At least that is the image that I come up with.
I am thinking of it in the moral sense. There are other senses.
Principle as moral law
It represents a set of values that orientate and rule the conduct of a concrete society. The law establishes an obligation in the individual's conscience that belongs to the cultural field in which such values are accepted. It supposes the liberty of the individual as cause, that acts without external coercion, through a process of socialization.
# 1 Principle as cause
* 1.1 Principle of Causality, as efficient cause
* 1.2 Principle as a final cause
o 1.2.1 Utility and Morality
# 2 Principle as law
* 2.1 Principle as scientific law
* 2.2 Principle as moral law
* 2.3 Principle as a juridic law
# 3 Principle as axiom or logical fundament
* 3.1 Principle of Sufficient Reason
* 3.2 Principle of Identity
* 3.3 Principle of contradiction
* 3.4 Principle of excluded middle