Posterior Analytics translated by G. R. G. Mure
Numbered in terms of chapters.
71a - 73b
Aristotle starts by explaining what his object of inquiry is. He mentions scientific knowledge, but not what we mean by scientific knowledge like knowledge about biology or physics. He’s talking about demonstrations and arguments using prior knowledge to acquire new knowledge. I’m not going to get into the nuance of the word here, other than to say that by science he basically means demonstrating conclusions about things which are necessarily the case. So, this probably leaves out things about imagination, possibility, intuition, and so on.
1 - You can know what a right triangle is, and you can know that what you are looking at is a right triangle. The difference is that you need to investigate the triangle you are looking at to know that it is a right triangle. This seems problematic when we think about right triangles that exist but we are unaware of. Do we then not know what all right triangles are? Do we only talk about right triangles in terms of the right triangles we have seen and nothing else? If the only prime numbers you know about are the ones you memorized, and you don’t have a rule to calculate prime numbers, then in what sense do you actually know what a prime number is? Anyway, you can know about things universally, like how you know that the concept right triangle refers to all right triangles, including those you have not observed and those that have yet to exist.
2 - Premises must ultimately rest on a premise that meets the following criteria: true, primary, immediate, better known than the conclusion, and prior to the conclusion.
You probably can use the ideas ‘better known than the conclusion’ and ‘immediate’ for figuring out first principles of a field. He doesn’t mention sense perception or what this ultimate grounding is, but finding what is better known than the conclusion would be a process of reduction to sense perception in the Oist sense of reduction. Aristotle specifically mentions that by prior, he means prior in terms of man’s knowledge (epistemologically prior), not metaphysically prior.
3 - Circular demonstration (proving in a circle) is impossible - except when the attributes imply each other. So you could prove in a circle about mind and body, because they imply each other.