A Closed Mind, like a computer, has a fixed operating system.
The operating system determines which & how the programmes will run.
Our sub-conscious mind determines which programmes & beliefs can operate on our human mental system.
A fixed operating system & a closed mind cannot change its beliefs.
Its beliefs are convictions because it cannot change its mind & think in any other way.
A closed mind cannot accept a different belief system as a viable operation.
It believes in the truth of its own programming, which makes all other operating systems false & inoperable.
A closed mind never allows an upgrade in the operating system.
It may adopt a new compatible belief or programme, but only if it runs on the existing operating system.
It is programmed with the belief that you cannot teach an old dog new tricks.
It cannot find a way to talk to Siri on an iPhone 3.