Do u have to?

You don't have to use brown sugar in that recipe. You can substitute the brown sugar with more white sugar but the texture of your cookie will be different. White sugar makes crisper, crunchier cookies while brown sugar makes chewy and moister cookies. Also, you don't have to have the raisins in the cookies if you don't want to. If leaving them out, just cut the baking soda back to 3/4 tsp or just replace the raisins with nuts and keep the soda the same.