The phrase "accept the principle that" is correct and usable in written English.
You can use it when discussing the acknowledgment or agreement with a fundamental idea or concept in a formal or academic context.
Example: "In order to move forward with the project, we must first accept the principle that collaboration is essential for success."
Alternatives: "acknowledge the idea that" or "agree with the notion that".
I accept the principle that the EU could distribute money to the poor and marginalised.
I accept the principle that the EU should represent our joint interests in creating treaties for the betterment of humankind.
The FARC's negotiators have yet to accept the principle that such crimes must be punished, even with milder sentences than would normally be imposed.
Ms. Goulard and Mr. Pagrotsky both accept the principle that the central bank should be totally independent of politicians when it is setting interest rates.
Most Indonesians accept the principle that nobody will invest capital unless they expect a return, says Nick Cashmere of CLSA, a brokerage.
I will happily accept the principle that, historically, we hardly know how long a film is, or ought to be, or why.
When asked about sanctions, Crowley said "... in the Secretary's phone call with Micheletti she reminded him about the consequences for Honduras if they fail to accept the principles that President Arias has laid out, which would -- it has a significant impact in terms of aid and consequences, potentially longer-term consequences, for a relationship between Honduras and the United States".
But by accepting the principle that spending must fall, Mr Cameron says he has already been braver than the government.
He argued instead that Osborne's reform showed the Conservatives had accepted the principle that the wealthy should pay more for the homes they own.
But one of the upshots is that publishers have now firmly accepted the principle that ebooks should be cheaper than their physical counterparts.
He has never accepted the principle that the Palestinian state should get 100% of the land taken by Israel in 1967.
