You sure can, but the soap won't be exactly the same as it is with lard.
The two oils most commonly used to sub for lard or tallow are vegetable shortening and palm oil.
I live in the midwest and very, very, very rarely in the past 10 years of soap making have I heard anyone against the use of lard or tallow in soap. On the other hand, I've have folks looking for soaps made with lard.
If you take a look at a commercially made soap, you'll find their #1 ingredient is Sodium Tallowate ... i.e. Tallow