| Posterior Analytics | |
|---|---|
| Room | Systems |
| Field | Logic, epistemology |
| Known for | Demonstrative knowledge, first principles |
| Key figures | Aristotle |
Posterior Analytics — Aristotle's Theory of Scientific Knowledge
The Posterior Analytics (Ἀναλυτικὰ Ὕστερα, c. 350–335 BCE) is Aristotle's foundational treatise on scientific knowledge (epistēmē), demonstration (apodeixis), and definition. Part of the Organon (the collected logical works). Builds on the syllogistic logic of the Prior Analytics.
A science (epistêmê) is a deductive system. It begins with undemonstrated first principles (archai) and derives all other truths from them through demonstrative syllogisms.
First principles must be:
1. True — cannot be otherwise
2. Primary — not derived from anything prior
3. Immediate — no middle term between subject and predicate
4. Better known — more familiar than what we derive from them
5. Prior — in the order of being (not necessarily in the order of our discovery)
6. Explanatory — the cause of what we derive from them
Two kinds of first principles:
"By demonstration I mean a syllogism productive of scientific knowledge, a syllogism that is, the grasp of which is eo ipso such knowledge." (I.2)
| Type | What it proves | Status |
|---|
|------|---------------|--------|
| **Demonstration** | Certain, necessary, universal truths | The only real knowledge |
|---|---|---|
| **Dialectical syllogism** | Probable premises | Opinion, not knowledge |
| **Sophistical syllogism** | Seemingly perfect but not | Fallacy |
Key constraints:
If all knowledge requires demonstration, and demonstration requires known premises, we face an infinite regress. Aristotle's solution: not all knowledge is demonstrative. First principles are known by nous (intuitive intellect), not by demonstration. They are grasped through experience and induction, then recognized as self-evident.
Book II investigates definition (horismos) and essence (to ti ēn einai, "what it was to be"). Key questions:
Aristotle's answer: we grasp essences through a process starting from perception → memory → experience → induction → nous (intuitive grasp of the universal).
The famous final chapter describes how first principles are known:
Perception → Memory → Experience → Induction → Nous
(aisthēsis) (mnēmē) (empeiria) (epagōgē) (nous)
"Noùs is the originative source of scientific knowledge." (II.19, 100b15)
This is a non-inferential grasp of first principles — not deduction, not induction in the modern sense, but a direct intellectual intuition of universals that emerges from repeated experience.