Is there a way to leave a blank value using fresnel?

So here is what i’m trying to accomplish:

i’d like it to work so that if the switch parameter is set to false the fresnel would keep on doing his thing with no actual parameter going in, is this possible ? or is there another way I could do this ?

Thank you for your time !

The Fresnel wants a world space normal. Which if empty would be the following:

You are boss ! :smiley: thanks !