The one example we have of truth are those of mathematics. A2 + B2 =C2 is the Pythagorean theorem. It's true of all rectilinear triangles. Deductive logic can give us necessary truths, but Hume says their mere tautologies, that is, facts about words. All bachelors are unmarried men, is a classic example. This is such a tough one, Newtus. For example, Descartes, " I think, therefore I am" makes sense. Then one can break it down and ask, "Are you sure YOU"RE thinking? And what is this think called "I"? Hume and many others claim that one is a bunch of experiences and memories, there is no I. Locke, believed that the mind was an association of ideas that act as gravity that are attracted to something something mysteriously knits it all together. Many consciousness is just an illusion! Skepticism is crucial to philosophy, and truths seem to be only tentative. This is where one flexes their mind and takes the greatest things said and thought, finds sound arguments and create a broad worldview that encompasses. I use pragmatism (W. Jame's pragmatism, What is in your highest virtue to believe in) towards much. Quite honestly, I'm agnostic about a lot of things, but I have many inclinations. Still, I love the freeplay of ideas. If there is one quality of a true philosopher it would have to be the wonder of ideas and the free play of those ideas.

Is nature purely physical? The argument here would be if minds are material or not. Take the brain, expand it to the size of a building and what are you going to see? You're going to see mostly fat, protein, and water. Which translates into neurons that consists of axons, dendrites, and synapses. No where in the mechanics do we see an idea, motive, desire, feeling, sensation, or perception. However, we could press further and look at the levels of information. Some thoughts though. If physics is at base built on probablism, then how come we can have necessities in logic that aren't probabilistic, or mathematics that are so precise. If reality is probabilistic from head to toe then why are there these anomalies. You might want to look up qualia and the mary problem. It's a classic rebuttal against a complete physics in principle.

I think that intentions matter, not consequences. This is Kant (deontology) vs John Stewart Mill(Utility). As for a rule being moral, I mean if you're living in a society with rules such as... slavery is okay, then isn't that still wrong? You might think so but WHY is it wrong becomes the question. For Kant, if you're rationally autonomous then you are part of the moral community. Regarding others, you ought not use others as a means to your own ends.For instance, if you make a person a slave then you are taking them away from the moral community and that prohibits them to be rationally autonomous. Therefore, morality is negated and whose to say that that person's rational autonomous isn't going to be taken. You're suppose to act as if you're actions are universally applied, which would make slave owning seem unmoral because then all would be slaves if you stuck to universalizing your moral precept. That one isn't as clear as lying. If you lie to a person you are using them as a means to your own ends, and not their own. Therefore if you universalize this moral precept then everyone would lie and their would be no morality because everyone would be a means to other's ends.