A priori and a posteriori are related concepts of scientific and philosophical discourse, denoting, respectively, the knowledge that precedes and is independent of experience and knowledge obtained from and conditioned by experience. A priori forms of sensuality and thinking organize, give coherence and order to chaotic knowledge acquired from experience with the help of the senses. On the other hand, a posteriori knowledge obtained with the help of sensory perception is accidental and untrue. It is based on experience and does not exclude the possibility of acquiring a new experience in the future that does not coincide with the old one. Therefore, in my opinion, of these two methods, the best means of obtaining knowledge is a priori.
In Plato’s teaching about recollection or anamnesis and innate ideas, the idea of the independence of reliable knowledge from experience is consistently carried out. Plato draws attention to the knowledge of the essence of a thing, which is unchangeable and is revealed in the concept of this thing (Lawhead, 2015). To know for sure what this thing is, it is necessary to know it even before getting to know it, that is, in advance. Thus, to learn, from his point of view, means to restore the knowledge that already belongs to someone which is the first argument in favor of a priori.
Kant considered a priori form of the organization of knowledge, which is filled with a posteriori content, ensuring the universality and necessity of scientific knowledge. The philosopher referred to the a priori spatial-temporal characteristics of objective knowledge and pure rational concepts – categories, and pure rational principles – ideas (Lawhead, 2015). Kant’s apriorism played an essential role in overcoming one-sided empiricism, pointing out the necessary presupposition of knowledge, the relationship between experience conditions, and its results. Based on the example of Immanuel Kant’s worldview, it can be concluded that a priori is a more reliable means of obtaining knowledge.
What is obtained from a posteriori is accidental and temporary; after all, experience is constantly changing, and it often happens that the new one entirely refutes the previous experience. A posteriori knowledge acquires universality only by relying on a priori knowledge; otherwise, it does not have any lasting meaning. For such knowledge to become universal and necessary, it should be brought under a priori forms of knowledge. Therefore, a priori is a better means of obtaining knowledge than a posteriori.
Reference
Lawhead, W. F. (2015). The voyage of discovery: A historical introduction to philosophy. In S. Milewski (Ed.), Epistemology, metaphysics and John Locke (pp. 223-224). USA, Stamford: Cengage Learning.