Bad switch:
Mostly this happens due to bad lever switch (multi-function switch) that controls the wipers, in that case the switch will have to be replaced.
Faulty relay:
The windshield wipers relay could be stuck. The relay is located in the engine compartment fuse box under the hood in 2017 Lincoln MKC. It will be labelled "R6" on the back of the cover, check your owners manual to confirm.
Rain sensor problem:
Does your vehicle have rain sensing wipers? If yes, then try disabling the feature to rule out any problem with the sensor.