Carlos Sainz will not be frozen out by McLaren in 2020.
Normally, a move like that would result in the team shutting its departing driver out of knowing about car developments for the following year.
But Brown is quoted by Speed Week: "Carlos is a professional, and we are professionals. I believe that if you stop putting everything on the table for the driver, it will affect performance.
"You can't be successful like that," he added.
McLaren is struggling financially at present, amid revelations that insolvency could even lie ahead as soon as July. There are reports that the National Bank of Bahrain could step in with a loan.
"We want to get the most out of the shortened 2020 season," said Brown. "So I don't think it is very productive to withhold information from Carlos.
"In normal times, it would have been obvious not to show Carlos everything, but we will continue with the 2020 chassis next year," he added.
"The development of today's car is largely frozen, so we will continue to maintain our excellent relationship with Carlos. We have been very honest with each other since Carlos told us that he was negotiating with Ferrari."