Making a basic vocabulary of the philosophy of science Hi, I just posted this on another board I'm at that often has debates where issues of science sometimes come up, along with the standard annoying arguments like "it's just a theory". This is an attempt by me to clear things up. So, this is what I have so far: fact - A scientific fact is a single, specific piece of data, for example "at 10:02:03 PM the 24th of August 1998, while standing in my lab - I let go of a ball. Immediately afterwards, the ball dropped down". That sentence describes two facts which are, like all scientific facts - completely useless alone. But they can provide evidence for and inspire a hypothesis. hypothesis - Where facts are specific, a hypothesis is general - for example "whenever you let go of a ball, it will fall". A good hypothesis can be useful because it predicts and explains things. There is a catch, however. All hypotheses depend on Inductive reasoning, in the wide sense of the expression. theory - a theory is a well established and thoroughly tested hypothesis. induction, in the wide sense of the word - induction in this sense of the word is a kind of reasoning where you make a conclusion about a greater amount of things based on a fewer amount of things. For example, "all the pieces of copper tested so far conducted electricity - this means that all copper conducts electricity". Induction isn't 100% reliable - Bertrand Russel has an example of a turkey who, every day observed that the farmer came and gave him food at 9 o clock - and he concluded that the farmer would keep doing so. Which was true every single day until one Christmas morning.... In spite of this, we blindly entrust our lives to inductive reasoning every day, all the time - because there is often no alternative. Every time you turn on your computer, assuming it won't make it blow up in your face, every time you step off the sidewalk in to the street - assuming it's not just paper painted to look like asphalt, covering a huge abyss. Every time you turn your steering-wheel right, assuming that your car will turn right. In all these cases you're going from a small amount of cases (all the times it's happened before) to a greater amount of cases (all the times it's happened before, and also this time) Deductive reasoning - Deductive reasoning usually (if not always) goes from a limited amount of things to an equal or lesser amount of things and is always truth preserving. That means that if the premises are true, then it's a logical necessity that the conclusion is true. For example: Premise 1: if cars can transform in to demons, then all pies are tasty Premise 2: cars can transform in to demons conclusion: all pies are tasty Proof - Though most people use this word in a very loose and everyday way - proof, in the specific philosophical sense, only refers to things like the above, where the truth of the reasoning is given through the structure of language, mathematics or logic. In science, the reasoning is about and is dependent on the physical world - so a conclusion will be contingent, which means that it's neither logically contradictory nor necessary - you have to check with reality. Evidence - A fact in the role of supporting a hypothesis or a theory. Falsification - While you'd need to check all copper in the universe to show for certain that all copper conducts electricity, you only need one piece of copper that doesn't conduct electricity to falsify it, that is to prove that it's not true.