Consider the following argument: “If we admit that infants have a right to life, then we must also admit that third trimester fetuses have a right to life. But if we admit that third trimester fetuses have a right to life, then we must also admit that second trimester fetuses have a right to life. And if we admit that second trimester fetuses have a right to life, then we must also admit that embryos have a right to life. And if we admit that embryos have a right to life, then we must admit that every fertilized egg has a right to life. Therefore, since it is obvious that infants have a right to life, so too does every fertilized egg.” This argument is an example of a(n)