Imagine you're a scientist, working in a lab. You've got some fiddly little thing that you're manipulating with gloves and studying. Then, after a long day of fiddling and studying, you wander home, collapse in a comfy chair, pick up a novel, and totally immerse yourself in it.
What we've just described is extraversion and introversion, in the socionics senses of the word: objects versus integrated experiences.
Next, let's look at rational versus irrational.
Do you know those people who are always running around saying how things 'should' be? Maybe you're one of them! Now, what about those laid back types? The ones who just take things as is?
This is the distinction Socionics makes between rational and irrational elements: what something "is" versus what something "ought to be".
With me so far? Let's take a look at one of the less obvious distinctions: internal and external.
We're going to take an apple, here. Let's call him Bob, since we'll be using him again later.
What can you say about Bob? He's red. He could serve as an improvised projectile. He looks juicy. He grew on a tree.
That he's red and juicy is certainly an observable characteristic. That's what Socionics calls "external": it's a tangible, physical property.
But, you didn't see him growing on a tree! Nor is he *actually* in flight towards some innocent bystander's head. These are "internal" properties: things that are not directly observable. (Though, of course, you can reason out that he grew on a tree, or that he has enough mass to serve as a meaningful projectile. [distinction between reasoning and observation here])
Another example, perhaps more clear. Simple arithmetic is "external": if you have an apple in one hand, and Bob in the other, you have two apples (1 + 1 = 2). Ethical considerations are largely internal: how else could cannibalism be considered so wrong in the west, yet a natural part of living for others?