3When we use "deductive reasoning", we go "down from" the general idea, the theory to the particulars. When we use "inductive reasoning", we go "up from" particulars to a general idea. We often speak of general ideas as being at a "higher level" than details. If that doesn't make intuitive sense to you, I don't know that it's worth trying to see it. Just accept that someone picked one to be high and the other low. Like why are the Western and Eastern Hemispheres so names? You can go west from the Western Hemisphere and get to the Eastern Hemisphere. It's arbitrary, an historical accident. – Jay – 2015-06-29T21:17:40.063

Interesting question, not entirely clear what you're asking. To deduce is to decrease the number of possible truths. To decrease in number is to go "down" in number. To reduce the possible truths "down" to a single truth is to deduce. You lead the line of reasoning in a direction that logically decreases the number of possible truths. – Ross McConeghy – 2014-08-19T22:58:45.183

6This question appears to be off-topic because it is not about learning English. The OP already understands these words and their usage, and is asking about their etymology out of curiosity. This sort of academic question would be best asked on ELU. – snailplane – 2014-08-21T20:12:57.837

1@snailplane: Another good point. But this OP has a peculiar predilection for asking us to help him "intuitively" understand long-established usages in terms of current syntax, semantics, and familiar figurative usages. Which usually have little relevance to why language changed the way it did many generations ago. – FumbleFingers Reinstate Monica – 2014-08-21T20:56:51.147

1These terms entered English with their meanings already fixed; the question goes beyond English to the figurative use of Latin morphemes by the Romans. – StoneyB on hiatus – 2014-08-22T01:31:57.687