Books about philosophy and ethics are generally found in the B-BJ section. You can browse that call number range on the 3rd floor (in the "stacks") and on the 1st floor, in the reference or topics area.
B 1 - B 5802 Philosophy
B 808 - B 849 Philosophy. Modern. Special topics and Schools of Philosophy
BJ 1 - BJ 1725 Ethics
BC 1 - BC 199 Logic
BD 10 - BD 701 Speculative philosophy. Metaphysics. Epistemology. Ontology
BH 1 - BH 301 Aesthetics