What the problem of universals asks — do abstract properties (redness, roundness) exist independently

What nominalism claims — only particular things exist, universals are just names

Nominalism posits that only individual objects exist, universals are mere linguistic constructs

What substance dualism claims — mind and body are fundamentally different kinds of stuff

Dualism posits that mind and body are distinct, non-physical and physical substances, respectively

What Plato's theory of Forms claims — abstract perfect Forms are more real than physical copies

Plato's theory of Forms posits that abstract, perfect Forms represent the truest reality, surpassing physical copies

What Kant's categorical imperative says — act only by rules you could universalize

Act according to maxims that could be willed as universal laws

What qualia are — the subjective, felt qualities of experience (the redness of red)

Qualia represent the intrinsic, subjective aspects of conscious experiences

What the underdetermination of theory by data means — evidence is always compatible with multiple theories

Underdetermination implies that evidence does not uniquely determine a single theory