Proposal vs. Proposition (Mailbox)

What is the difference between proposition and proposal?

[Remember, keep sending in your questions to chris.brecheen@gmail.com with the subject line "W.A.W. Mailbox" and I will answer questions about once a week.  I will use your first name ONLY, unless you tell me explicitly that you'd like me to use your full name or you would prefer to remain anonymous.  My comment policy also may mean one of your comments ends up in the mailbox. Don't think for a second that I'm too good to pick an easy question when I'm tired.] 

Johnny asks:

[Note. I have consolidated a few of Johnny's paragraphs (each sentence was its own in his email to me) for space reasons.]  

I have a question about proposal vs. proposition. 

From Learner's Dictionary: Proposition: something, such as a plan or offer, that is presented to a person or group of people to consider. Proposal: something, such as a plan or suggestion, that is presented to a person or group of people to consider. Almost identical meanings but different connotations, I think? When you want to get married or start a business, you use proposal. When you want to have sex or change a law, you use proposition.

Why?

They sound like they have the same root word too. Why two different words? And in any situation where you can use one, the other fits just as well. It just sounds weird because of what we're used to hearing I guess? I appreciate your help with this clarification. 

Thanks!

My reply:

Before I dig into this.....confession time. I was dead-ass tired last night after yesterday's article was GUTTED out over 8 hours and a painful revision, I slept twelve hours last night, and I'm still recovering from those 70-hour-weeks earlier in the month, so I deliberately picked an easy question to field today. 

Ain't English grand? We have synonyms that are so close together yet still with such subtle shades of difference that even the people who intuitively use the right word at the right time MAY NOT BE ABLE TO ARTICULATE WHY. Particularly native speakers.

These words are amazingly similar but your question actually does have an answer Johnny, and every native speaker reading this is likely to have a "Holy shit...he's RIGHT!" moment in just a few seconds. They may want to sit down.

In most cases, a "proposition" is the word used when the answer is going to be yes or no. (For example propositioning someone for sex.) A proposal is more complicated and usually involves consideration and discussion––more back and forth. The only difference in these definitions is is that "suggestion" is replaced with "offer." An "offer" is something you either take or leave (or maybe counteroffer). A "suggestion" has more....plasticity. It's almost more of a starting point.

Think of these two phrases:

"I suggest $10,000 advance and fifty cents on the unit for your new Dark Lord vs. Farmer space opera."

~or~

"I offer $10,000 advance and fifty cents on the unit for your new Dark Lord vs. Farmer space opera."

See how the first kinda feels like you have some room to negotiate and the second just feels like you can sort of take it or leave it?

"But what about a marriage proposal?" I hear you ask. That's got a straight yes or no answer in most cases. You're absolutely right. But that's "proposal's" second meaning. (Proposition also has another meaning–a statement that expresses an opinion or judgement–that is technically outside the boundaries of your question.) Literally one entire definition of "proposal" is JUST about marriages.

And of course "proposition" also has other meanings. The legal meaning ("Stop Proposition H! It's bad for the kids!") has to do with ballot measures that are voted on directly by voters instead of by the legislative branch. Also it has a mathematical meaning of a statement that is either true or false. (Although again in these two cases, you see that you can either vote yes or no legally or prove it or not mathematically, so there is a YES or NO dichotomy built into the emotive force of that word.)

If you think about it, the marriage one makes a certain sort of sense as well. Language evolves but sometimes words and phrases get fixed (or even become idioms). A marriage used to be a LOT more of the start of a business arrangement between two families that might involve some back and forth negotiations. The recent development where it's just the proposee who decides yes or no is kind of sign of modernity.

Just don't let the fact that the movie isn't called Indecent Proposition mess you up too bad.