Philosophy is the first, oldest, and largest discipline, leading to the founding of the first university by Plato and the formalization of logic and science by Aristotle, as well as spawning many other fields of study with recent major additions being psychology, sociology, the theories of mind used in AGI research, and so on. Philosophy's affect on humanity's knowledge of the world is exemplified by things like xefer, which show that all articles on wikipedia are fundamentally predicated by the page for philosophy. Logic and critical thinking are sub-fields of philosophy, which explains why philosophy undergrads compete with physics undergrads for the highest average scores on the LSAT and GRE.

Philosophy concerns itself with the broadest and most general of questions. Philosophers do not study how rocks be or how living organisms be, as those are what geologists and biologists study, respectively. Instead the philosopher studies the nature of being itself, without specificity. Where all other disciplines are narrow in their scope and application, philosophy is broad and universally applicable. It is easy to argue that philosophy is the most practical of all studies, since a focus of philosophy is 'the good' and knowing what 'the good' is means you will know what is good to do in any particular situation. It is also easy to argue that studying philosophy is the most important thing you can do, since asking the question of what importance is, deliberating its answer, and analyzing its accuracy, are all part of the philosophical practice such that we could not define importance or grant anything as being important without philosophy, making philosophy the mother of important things.

- Types versus Tokens.

- Necessary versus Contingent conditions.

- The Myth of the Given by Wilfrid Sellars.

- Leibniz's Law, Max Black, and particles in field theory.

- Why no framework for dualism can be true.

- A matter of ontology. Ontological studies either go from definition to experience, or from experience to definition. For example, if we came across someone eating meat and claiming to be a vegetarian, then going from definition to experience, we would know the person was misinformed or confused. But if we went from experience to definition, then we have met a meat-eating vegetarian. This is demonstration that the second method is improper and devolves into a world of married bachelors and square circles with no consistent meaning or means for evaluation, a worldview that we would say is structurally incapable of justifying itself. So it is the case that we must go from definition to experience in matters of ontology.

- As my personal conviction, I do not believe existence is suffering like lots of the existentialists and theists believe. I agree with Dimorphique that existence is fundamentally playful. I think reality is much like a well-structured game and the genre is comedy. But even if you disagree, I'd recommend that whatever you do in life, you should do it aggressively and at the expense of others.

- It is always better to know than to not know. A contemporary like Madva might counter with the example that knowing whether the number of air molecules in your room is even or odd obviously has no practical or meaningful use, but I would point out that the knowledge that would be required to determine this piece of information justifies its pursuit many times over, and that knowledge has near-endless practical and meaningful uses, making it always better in capacity to know than to not know. It's not very valuable to believe in information hazards because information is only ever hazardous if you don't know what you ought to do with it - a problem solved by gaining more information. The real hazard then is acting without thinking.

- Classically, knowledge is "justified true belief," as formalized by PlatoIt's worth noting that Plato also rejected similar formulations of knowledge like "true judgment with an account" in his work Theaetetus.. This definition held for two and half thousand years until Gettier came along and challenged the security of what would count as valid justification, also described as epistemic luck, but if you want to BTFO academic philosophers, just point out that Plato already anticipated this objection and said that bad evidence isn't justification, so Gettier is a non-problem.

- The seven steps of the Socratic Method.

- Deduction vs. Induction vs. Abduction.

- Problems with induction: Deniz's comment.

- Hegel's dialectical method, or "Creation through destruction." (dialogue vs dialectic)

- Objectivity versus Subjectivity. (note on aesthetics vs math)

- All knowledge, all pieces of information, have to be knowable to at least one possible knower. This is 'principled' knowledge - that all things can be known, at least in principle. The only limitations beyond that would be for practical reasons, like if no one had visited the moon yet then we wouldn't know what it's soil was composed of, but we could know by visiting. Principle versus practical. So everything can be known in principle or we wouldn't have access to any information at all. Wittgenstein's private language arguments (remarks 243-304, on page 48 in the PDF) formally proved this and saved humanity from Kant's transcendental horizon, but lots of people don't read or don't understand Wittgenstein so I'll put it in a simpler way. Suppose we found an opaque box floating in space. This box was opaque not just to light but to all forms of probing available and could not be probed in principle, much less for practical reasons. It would be the case then that anything could be in this box, and anything means anything. If anything could be in the box then the box could contain a piece of knowledge that proves all other pieces of knowledge false, including that proof. This is a contradiction and thereby self-defeats. It is therefore not possible that this box exists, or any principally opaque knowledge for that matter. We find then that all things in the world can, in principal, be known. To paraphrase Witt, "To place a limit on thought is to think both sides of the limit."

- Existentialism was a philosophical movement focusing on figuring out how the world works starting from the perspective of your individual experience. Existentialism has nothing to do with threats against humanity, and if you think it does, then you got duped by a dilettant. If you see someone say something is 'existential' and they're not using it to mean something is concerned with the nature of its being from the perspective of its being, then they are using the word wrong and should be laughed out of the room. It has also almost entirely died becuase it is a fundamentally flawed method, leaving too much to induction in a space that otherwise necessitates the supremacy of deduction, but you can read the existentialists themselves for more information on why and how it fell apart if you're truly curious.

- Invented versus discovered. People get told what logic does without ever getting told what the being of logic is. This is like asking what a shovel is and being put to digging holes. So for all the first-years out there, let me tell you something your philosophy professors won't: there is only one framework for logic, and it was discovered by Aristotle. If you look at things like math which are supposed to be purely objective and count as discoveries about the nature of the universe, you run into some devestation upon asking why there is more than one framework for math. This is a serious problem for mathematicians. If math is objective, meaning informative on objects out there in the world in a definitive way, then why does asking two different math frameworks the same question result in different answers? If we take two frameworks of similar purposes like Newtonian Calculus and Leibnizian Calculus and ask them both where the center of mass of the Moon will be in one day's time, they will return two different points in space as an answer to that question. This is to say they will tell you the Moon is both in one place and not in that place at the same time in the same regard, which is of course a contradiction, making math invented and somewhat arbitrary in application. Conversely, if you pose the same argument to what people think are two different 'frameworks' of logic, they return the same answer. This demonstrates a unity in logic that doesn't exist in math on top of showcasing that logic is discovered and not invented. There are lots of other formal proofs for this but you get the point, and it should be obvious in retrospect since what we call formal logic is 'first-order logic' and math is 'second-order logic', meaning secondary and fundamentally less important as a study.

- Necessary versus Sufficient conditions.

- Consistency and Authority. (Logic as an authoritative tool) The word 'authority' would not have a consistent definition without logic, for consistency is a property of logic, and you can only make consistent that which follows logic, granting logic the status of highest arbitrator or highest authority when it comes to reason.

- The principles of arguing well: logos, ethos, and pathos, which means valid arguments, authority, and emotive appeals, respectively. What this looks like in an actual discussion - don't say a contradiction, don't cut people off unless you need clarification, and add to your opponent's argument before taking away from it. The last clause can be considered a modified version of the principle of charity except that this version will get you what you want far more often. As a point in favor of the utility of emotive arguments in the face of an otherwise purely objective and logic-based discussion, Rochefoucauld states, "The passions are the only advocates which always persuade. They are a natural art, the rules of which are infallible; and the simplest man with passion will be more persuasive than the most eloquent without."

- Emotions are rational, you agree with me and I can prove it.

- Biting the bullet.

- The permissability of tu quoque and ad hom.

- Deontology versus Consequentialism.

- Axiology and aesthetics.

- The inherent good of knowledge.

- Is-Ought and Naturalism.

- The non-distinction between high and low art.

- Philosophy versus sophistry.

- Philosophical zombies.

- Political theory.

- Value versus profit.

- Test views with absurd trolley problems.

- Bugmen.

    The Enlightenment is what birthed people like Descartes and Thomas Hobbes (or vice versa since people like Descartes are why we call it the Englightenment to begin with) and Descartes and Hobbes are what people like Spinoza, Leibniz (plus Newton on this front), and John Locke are responding to. John Lock is who Berkeley, Thomas Paine, and Rousseau are directly responding to, Berkeley is who Hume is responding to, Hume is who Kant is responding to, Kant is who Fichte and other German Idealists (like Schiller) are responding to, all the German Idealists are who Hegel is responding to, Hegel is who Marx, William James, and Schopenhauer (Schopenhauer is also the first major atheist in modernity - noting this because it marks modern atheism as only 170 years old) are responding to, Schopenhauer is who Husserl and Nietzsche are responding to, Nietzsche, Husserl, and Kierkegaard are who all the Existentialists (Sartre, Beauvoir, Jaspers, Camu, arguably Nishida, etc.) are responding to, Marx and friends are who Weber and Gramsci are responding to (important for Frankfurt school), and Positivists have begun existing here as well (Gottlob Frege, Alfred North Whitehead, Bertrand Russell, G. E. Moore, AJ Ayer, W.V.O. Quine, Wittgenstein, etc.).
    The Existentialists and Positivists are who the rest of the 19th-century philosophers (split into structuralists like Nozick, Popper, Rawls, Merleau-Ponty, Adorno, Horkheimer, and post-structuralists like Deleuze, Guattari, Foucault, Derrida, and Bataille) are responding to, and those are who contemporaries (Zizek, Chomsky, Chalmers, Ray Brassier, Nick Land, Habermas, Sloterdijk, Kripke, Nagel, Dennett, etc.) are responding to. There are a lot of contemporaries focused on older stuff rather than trying to further discussion on new things, like Markus Gabriel who has tasked himself with trying to 'fix' German Idealism, but these people you can mostly ignore.