I am a new learner to logic and philosophy, after spending some time reading Introduction to Logic by Copi, Cohen & McMahon, I'm stuck on this matter... please help me so I can read forward...
The Amazon Basin produces roughly 20 percent of the Earth’s oxygen, creates much of its own rainfall, and harbors many unknown species.
This sentence simultaneously asserts three propositions, concerning what the Amazon Basin produces and what it creates and what it harbors. The passage thus constitutes a conjunctive proposition. Asserting a conjunctive proposition is equivalent to asserting each of its component propositions separately.
Some compound propositions do not assert the truth of their components. In disjunctive (or alternative) propositions, no one of the components is asserted. Abraham Lincoln (in a message to Congress in December 1861) said, “Circuit courts are useful, or they are not useful.” This disjunctive proposition is plainly true, but either one of its components might be false.
I am genuinely confused by that last two paragraphs. What does it mean by "asserting each component separately of a compound conjunctive proposition" and "nothing is asserted in compound disjunctive proposition"?