St. Thomas Aquinas [Summa totius logicæ Aristotelis (Opusculum 48)] divides the operations of the Understanding in reference to the logical character of their products into
Ratiocination, or Reasoning. [—]
Ratiocination or reasoning produces inferences or reasonings, which are expressed by argumentations, as, ” I think, therefore I must exist,” “Enoch, being a man, must have died; and since the Bible says he did not die, not everything in the Bible can be true.”
Reasoning is the process by which we attain a belief which we regard as the result of previous knowledge. [—]
Again, a given belief may be regarded as the effect of another given belief, without our seeming to see clearly why or how. Such a process is usually called an inference; but it ought not to be called a rational inference, or reasoning. A blind force constrains us. [—]
The word illation signifies a process of inference. Reasoning, in general, is sometimes called ratiocination. Argumentation is the expression of a reasoning.
Reasoning-power; or Ratiocination, called by some Dianoetic Reason, is the power of drawing inferences that tend toward the truth, when their premises or the virtual assertions from which they set out are true.