What are the nuances between these three terms for intelligence: 知恵 [ちえ], 知能 [ちのう], 知性 [ちせい] ?

Question

In particular which one is closer to the idea of "ability to reason over things" as a quality of someone in particular?

What I believe is that 知識 on the other hand is closer to "knowledge" and "understanding"　and 眼識　is more about "discrimination, insight", but as an intellectual operation, not a property attached to someone, like 認識.

Answer 1

I'd add to @istrasci's answer that:

• 知能 is more oriented towards mechanical problem solving skills, while
• 知性 is more about reasoning and discerning abilities only thought to be possessed by humans.

Words like 人工知能 (artificial intelligence), 知能指数 (IQ) show this aspect of 知能. Also, because of these differences, you will hear more about "動物の知能" (animal intelligence) than "動物の知性" (animal intellect).

So, "ability to reason over things" as a quality of someone, will likely be about 知性.

Answer 2

知恵 - means "wisdom"
知能、知性 - means "intelligence" or "intellect"; my dictionary cites them as similar meanings
知識 - means "knowledge (of/about)"; that is, the knowledge itself, not the property of "having knowledge"

So, 知能、知性 are probably what you'd use for "the ability to reason over things" since 知恵 ("wisdom") has some kind of moral/ethical/right-wrong implications to it. I'd say that mathematically, 知恵 implies 知性／知能, but the converse is not necessarily true.