"without outside influence" is correct and usable in written English.
You can use it to refer to a situation, decision, process, etc. that is not influenced or affected by any external factors. For example: The jury's verdict was reached without outside influence.
Sakoku, the policy of radical isolation that closed off foreign trade and contact for more than 200 years, allowed homegrown cooking to develop without outside influence; then, when the country opened up again in the 19th century, it unleashed a pent-up craze for all things foreign.
And that freedom should be experienced firsthand, without outside influence.
Without definition, without outside influence, what would you most want to wear to go out?
Ultimately, the need for infant feeding to be a personal decision without outside influence was viewed as important.
"Our new album was produced by us, without outside influences," he said in a telephone interview, speaking in the soft West Country British accent that has been a familiar touchstone for millions of fans since the group's groundbreaking 1966 album, "Days of Future Past".
Without outside influences, microbial communities in these environments can continue to evolve in isolation - developing novel solutions to the problems that plague their soil counterparts, such as competition and the desire to fight for resources.
Under the premises their current powers were defined by, not without outside influences.
So you have to start asking yourself what Italian food would be without an outside influence.
If Oswald acted alone, without any outside influence, how and why did Jack Ruby pump a.38 slug into his gut two days later in the basement of the Dallas police headquarters?
Without any outside influence, the human body clock runs on a cycle that is slightly longer than 24 hours, and light sensitive cells in the retina help "reset" the body clock each morning to keep us aligned with the day-night cycle.
Graduate students tend to develop in the cocoon of their chosen lab without much outside influence.
