Is it possible to translate a syllogism into propositional logic? This is the example: All doctors went to medical school. Hanna is a doctor. Hanna went to medical school. Thanks a lot, Sebastiano

For any syllogism containing quantifiers such as "all," "some," and "no"/"none," you'll need predicate logic for the translation. Propositional logic alone won't suffice. But you could use propositional logic to translate a non-quantified argument that's at least similar to the syllogism: "If Hanna is a doctor, then she went to medical school. Hanna is a doctor. Therefore, Hanna went to medical school."

Why do we consider lying to be illogical even when it can produce good? I can think of many examples where lying can do more good than harm especially when its used for the benefit of others and not for selfesh gain. CAL

I'm not sure that most people consider lying to be illogical even when it can produce good. More likely they consider lying to be presumptively immoral , and they allow that the moral presumption against lying is overridden in some circumstances. Take a case of the kind you described: imagine lying to a known murderer about the (nearby) location of the next innocent person he's seeking to murder. In that case, I'd agree that the moral presumption against lying is overridden by the good of protecting the innocent person. All else being equal, one shouldn't lie. But sometimes all else isn't equal. Immanuel Kant (1724-1804) is a famous philosopher who holds that lying is never morally okay: that the moral presumption against lying is never overridden. In fact, he argues that lying is illogical in a particular sense. I don't find his argument compelling, but you can learn more about it in this SEP entry ; see especially section 5.

The Kalam Cosmological Argument has as its first premise "Everything that begins to exist has a cause" (at least in the form I've heard it). Often examples of "chairs" or "people" are given for things that began to exist. But this seems to be a category error - the Universe did not begin to exist in the same way that a chair does. Indeed a chair doesn't "begin to exist" in that it was created from other things. So to me it sounds like the argument overstates its case with "everything that begins to exist" since the only thing that has begun to exist is, well, everything. One could restate this premise as "The universe began to exist" could it not? Is I missing something or is this what is meant by this argument? If so it seems to be more of an assumption than the inductive reasoning I hear it being used as (e.g. "you've never seen a chair 'pop into existence' have you?").

I think you've put your finger on a dubious feature of the KCA. While I would say that a chair does begin to exist when it's created from pre-existing materials, I agree with you that if the universe began to exist, the universe didn't begin to exist in the same sense in which a chair does. So I think you're right to detect a questionable move from "Everything within the universe that begins to exist has a cause" to "Everything, including the universe itself, that begins to exist has a cause." It's not at all clear that the phrase "begins to exist" is being used in the same way both times. To the question "You've never seen a chair pop into existence, have you?" one can reply as follows: "I've never seen anything arising from pre-existing materials pop into existence, but that isn't relevant to whether something not arising from pre-existing materials can pop into existence."

Do philosophers really understand the concept of free will and have it formally defined? Dr. Maitzen in response to question 5711 was able to answer the question without asking what free will is yet for question 24592 he seemed not to know what free will is and seemed to treat is an abstract construction so is it just an abstract construction and if it is, why create the concept in the first place?

Thanks for your question and the chance to clarify. In Question 24592 , the questioner talked about philosophers "redefining free will" but never defined the term himself/herself. So I cited the definition of "free will" given at merriam-webster.com. I did so in order to indicate just how much neuroscientists would have to show before they could be said to have shown that we (routinely) lack free will as the dictionary defines "free will" . The merriam-webster.com definition treats free will as an ability. I'm not sure if that means treating free will as an abstract construction, but in any case if it's not a good definition then I suggest that you let them know. I myself see nothing wrong with their definition.

How can a certain bunch of atoms be more self aware than another bunch?

Good question, but I hope you didn't intend it to be merely rhetorical. Even at this early stage of our investigations, there's good evidence that the answer has to do with whether a given bunch of atoms composes a being that possesses a complex network of neurons. Some bunches of atoms, such as the bunch that composes me, do compose such a being. Other bunches, such as the bunch that composes my favorite pen, do not. Notice that we're not tempted to regard any of these similar questions as rhetorical: How can a certain bunch of atoms be more red than another bunch? How can a certain bunch of atoms have better eyesight than another bunch? And so on. I regard the question you asked as in the same boat as those.

Is there any single genuinely correct logic or so called all-purpose logic? If not, why should we find it?

I presume that you would dismiss out of hand the following answer to your first question: "Yes, there is a single genuinely correct, all-purpose logic, and there is no such logic, and there is more than one such logic." So I take it that your question presupposes that no correct logic could allow that answer to be true. If you're asking whether there's any good reason to abandon the standard, two-valued, "classical" logic routinely taught to university students in favor of some non-classical logic, then I'd answer no . Some philosophers say that we ought to adopt a non-classical logic in response to such things as the Liar paradox or the Sorites paradox, but their arguments for that conclusion have never struck me as persuasive. I think that the Liar and the Sorites can be solved using only classical logic (and bivalent semantics), or at least it's too early to conclude that they can't be. For a much more detailed answer, you might consult Susan Haack's book Deviant Logic, Fuzzy Logic:...

Assuming that the multiverse account of the universe is true -- and every possible reality is being simultaneously played out in an infinite number of parallel universes -- am I logically forced into accepting a nihilistic outlook on life? Or is it still possible to accept the truth of the multiverse account and still rationally believe that the pursuit of life goals is both meaningful and valuable, despite the fact that every possible outcome -- or potential reality -- is unfolding somewhere in another parallel universe?

I don't think that the multiverse account implies that it's irrational to pursue life goals or irrational to believe that pursuing life goals is meaningful or valuable. For even if the multiverse theory is true, I take it that you yourself are confined to one universe, our universe. The beings very similar to you who inhabit other universes are at best "counterparts" of you, which leaves open the question "What will you do with your life?" It may be well and good if one of your counterparts works hard to achieve wisdom, promote justice, or whatever, in some other universe. But his/her hard work isn't yours and doesn't occur in your universe. We need your shoulder to the wheel here!

what are the requirements for knowledge?

You'll find your question very thoroughly taken up in the SEP entry on the analysis of knowledge . As you'll see there, some philosophers go so far as to reject your question on the grounds that knowledge can't profitably be analyzed into other concepts. Enjoy!

Pages