The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Preposition is a noun. Confused? It’s a form of speech used to describe location, proximity, or a relationship. Examples include about, above, beneath, upon, without, are a few examples of prepositions. Prepositional phrases are discouraged in good writing because it adds filler with no real impact or point. Unfortunately, legal documents (aka “Legalese”) is teeming with prepositional phrases.
Proposition has multiple forms.
As a noun, it means the course of action presented to someone else: a business transaction, a request to have sex when both parties are strangers to one another, etc.
As a verb, it means the act of asking, or making that pitch to the other party.
So what makes a request a proposition? I would say the element of risk is high. The asker has more benefit than the person being asked (the “askee”), but the asker is trying to convince the askee that the benefit is mutual, or that the askee is going to benefit more.
The following story uses both words correctly:
Prewitt knew he had his work cut out for him. He was going to make a proposition to the governor that all laws be rewritten in a simpler language. This meant the hard work of eliminating all the dependent clauses and prepositions that made them so hard for everyday people to understand. This idea was beneficial in the longterm, but it would costs thousands in the short term to hire writers and reprint all that documentation.