Two sets of Aristotelian writings do not easily fit this scheme, the Metaphysics, and the Rhetoric and the Poetics. These are appended to the physical and the ethical writings, respectively. Dialogue was regarded as the appropriate form for philosophical arguments, and hence the acquisition of dialectical skill was regarded as crucial for students of philosophy. Aristotle's first great achievement was probably a handbook, now entitled Topics and Sophistical Refutations, in which he provided the first general analysis of dialectic and formulated rules for success in this kind of argument. Clearly, dialectical argument does not by itself lead either to incontestably true conclusions or to scientific knowledge.
Dialectical method aims to ensure that premises are plausible and that arguments are valid.
According to the Posterior Analytics, the ultimate premises or principles of a science are necessary truths. When a subject is sufficiently familiar, its governing principles become evident to reason. Deduction from these principles provides not only the knowledge that something is true, but also the reasons why it is true. For Aristotle, both are required for scientific knowledge. Aristotle's ideal of a science as a deductive system based on evident axioms had a considerable influence on the history of science.