Difference between "buy into" and "believe"

Question

In this video,

https://youtu.be/Lo52BObqCds

the senator keeps saying, "buy into my agenda".

Number two -- no. The answer to the question is that people buy into my agenda. And I do support the Second Amendment.

that is the wrong way to look -- first of all, the answer is, people buy into my agenda.

But I -- I -- listen. I respect -- you can ask that question, and I can tell you that I -- people buy into my agenda.

. . .

I wondered why the senator's keep saying the same phrasal verb, buy into, so I looked up the dictionary and found out that the definition of "buy into" is "to completely believe in a set of ideas".

So "to completely believe" is the difference between "buy into" and just "believe"? Is the senator keep using this verb to emphasize that lots of people truly/strongly believed his agenda? Or is "buy into someone's agenda" kind of a set expression and that's why he keeps using it rather than choosing some other verbs?

Answer 1

Yes, the phrasal verb buy into is stronger than just believe.

The metaphor being suggested by buy into is a monetary investment. You can use this same phrasal verb in a non-metaphorical sense by saying something like, "My brother convinced me to buy into his startup business, so now I own fifteen percent his company." When you buy into a business, you purchase partial ownership. You will prosper if that business prospers, and lose money if that business fails.

If you metaphorically buy into an idea or a person's political agenda, then it means that you have a personal investment in that idea or agenda. You passionately believe it is true, and may even take actions to help it succeed. If the agenda fails, you will feel a personal sense of failure. You are far more invested in the success of the agenda than a mere belief that it is true.

The Senator is probably using buy into in part for mere emphasis, but there's the additional implication that the people who buy into his agenda are committed (i.e., personally invested) enough that they will actively help his agenda succeed and actively punish those who oppose it.

Answer 2

Colloquialiam:

|I believe in your agenda.| means |I buy into your agenda.| They both mean the same thing. It means you accept what the person is saying.

There is a trend in English to use these types of phrasal verbs in some contexts. That said, to buy into an agenda or set of ideas is used in certain contexts, especially political or political-type contexts. "Buy into" a political platform, set of ideas, etc. American politicians are notorious for saying simple things in very colloquial ways. Like many AmE expressions, buy into something comes from the idea of buying a share or shares of a company: He bought into the company last year when he got 10,000 shares of it.

If you "buy into a company", you essentially believe it will prosper and make money for you. That is the meaning that carries over into the expression.

However, in "I believe what you say" or "I believe you", we would not say: I buy into you or I buy into what you say.

In this latter case, we would say: "I don't buy what you are saying." to say: "I don't believe what you are saying."

Please note: to buy into is not really a phrasal verb, it is a verb plus a prepositional phrase: to buy into a company, to buy into a set of ideas, and so forth.