Logic is a tool that helps us to reason things out and act rationally; much like arithmetic is a tool that helps us to keep count of things. And just as the building blocks of arithmetic are numbers, so the building blocks of logic are propositions. This is the main meaning of the word "proposition", which is quite different from the meanings of some of its cognates, such as "to propose" and "make a proposal", which mean something like "to put forward" or "to suggest".

Propositions are related by reasoning, or (logical) arguments: in a (logical) argument, propositions stand in a special relationship to one another, such that some 'follow from' others, (or are claimed to) - the 'conclusion' of such an argument is 'deduced' from the 'premises'. Note that this use of the word "argument" must be distinguished from other meanings it can have, e.g. when we say: "A heated argument followed," or "They had good arguments on their side."

Which of the following is/are (logical) arguments?

a) Close the window, because I am feeling cold.
b) Only rainy days or Sundays get me down; it must be raining, because it isn't Sunday and I am down.
c) After the rain, the sky quickly cleared and it became a fine day.
d) "I am right." - "No, you're not." - "Yes, I am." - "No, you aren't."