Obey? Or reason?

There is an order not to gather more than 3 people together.
They say there are reasons and it is mandatory to listen to instructions.
On the other hand, it doesn't seem logical to not gather more than 3 people even in a place where there is a military base or within walking distance of a military base.
To obey because perhaps there are things we don't know or because there is an obligation to obey?
Or if it seems to a reasonable person that there is no risk for him to act as he understands?