If closed no virus ...
And if Open then Viruses....
So how do you explain..Windows ...closed and lots of viruses...
Open like BSD and Linux ....very little viruses?
Closed in this discussion means the way programs and applications are reviewed and authorized. Most specifically to the smart phone industry. The model for PC vs Mac is based on Linux vs DOS. Very different set of circumstances producing a similar result.
Android allows anyone to make and distribute an app for use on their OS with no corporate oversight or authentication procedure. Open.
iOS is tightly controlled, apps are refused all the time and safety and integrity of the apps are assured. Closed.
In the PC world, it is: DOS based code vs Linux based code which accounts for the viruses and has much less to do with Open vs Closed, except the same premise is true, stuff can be written for PCs without any verification and just install itself with little to no user intervention. Mac is a little more strict in its coding and application execution permissions.