Epistemological arguments are those whose premises are based on to what extent the terms of the argument can be known with certainty. In other words, these arguments deal with degrees of certainty and probability. For example, “Drake’s equation” for life on other planets is a (failed) attempt at an epistemological or probabilistic argument. Some people use epistemic arguments to argue against abortion too. For example, how sure can a proponent of abortion be that the fetus is not a human being? If the proponent is not certain that the fetus is not human, they should not advocate the killing of it, since the killing of innocent life is wrong. If they are sure that the fetus is not a person with a right to life, then they must provide evidence and clear justification for this fact, and not simply emotive arguments based on other, non-equivalent, considerations. So in an epistemic argument of this kind, the justification of the conclusion is based on separating non-certain elements, like emotion, in order to arrive at a degree of certainty about the key terms.