More or less every textbook I can think of has many, many translations of symbolic sentences into English. Many, though by no means all, of the translations are in the exercises, and often you need to work from answer to question, but any good text will include lots and lots of examples. What I mean by "work from answer to question", by the way, is this: the more common kind of symbolization problem goes from English into symbols. The question will give you the English sentence, and the answer—often at the end of the chapter—will give the symbolic version. But if you look at the answer and trace it back to the question, you have just what you want. The question might ask you to put "No man is his own brother" into symbols. The answer might look like this:           ~∃x(Mx ∧ Bxx) But if you are given the answer and you know what question it answered, then you have your translation. Bear in mind that for this to work, you have to know what the letters stand for; that's often given in the question....

It seems to be a special case of a fallacy with many names: 'false dichotomy,' 'false dilemma,' 'black-and-white thinking' and 'either/or fallacy' are among the more common. When someone commits the fallacy of the false dichotomy, they overlook alternatives. Schematically, they assume that either X or Y must be true, and therefore that if X is false, Y must be true. The fallacy is in failing to notice that X and Y aren't the only alternatives. Your example makes the point. You've imagined someone assuming that either I accept a particular Republican policy X or I am a Democrat, when -- as you point out -- there are other possibilities. The situation you describe is a little more specific: the fallacious reasoner is making an inference from what someone is prepared to criticize. As far as I know, there's no special name for this special case, but the mistake is the same: overlooking relevant alternatives.

I agree with my co-panelist: "q because p" implies that "q" and "p" are both true. And on more than one reading of "if.. then" sentences, it will follow that "if p than q" as well as "if q then p" are true. It may be worth noting, though: not everyone agrees that when "p" and "q" are both true, so are "if p then q" and "if q then p." There's a different sort of point that may be relevant to your worry. Suppose Peter's smoking caused his emphysema. We can't conclude that if Petra smokes, she'll develop emphysema. Causes needn't be fail-proof. A bit more formally: Qa because Pa (which says, more or less that a has property Q because a has property P) doesn't allow us to conclude ∀x(If Px then Qx) (that is, for every thing x, if x has property P then x has property Q.) The truth of a "because" statement doesn't require the truth of a generalized "if...then" statement.

There are lots of questions we can ask about this argument, but I'd suggest that trying to shoehorn the issues into specific named fallacies isn't as helpful as just looking for places where the argument raises questions.. (It's interesting that in my experience, at least, philosophers invoke the names of fallacies only slightly more often than the average educated person does.) That said, here are a couple of quick thoughts. The first sentence offers two broad reasons for being altruistic: because in the long run it benefits both society and yourself. Take the first bit: if someone didn't already think they should be altruistic, how persuasive would they find being told "You should be altruistic because it benefits society"? If you want to turn to fallacy lists, is this a case of begging the question? (Don't be too quick just to answer yes. Think about the ways in which wanting to benefit society and acting altruistically might differ.) Turning to the next reason, is it incoherent to think someone...

I was intrigued that you take human knowledge to be very fragile. The reason you gave was that there's no way for all conclusions to be backed by premises, which I take to be a way of saying that not all of the things we take ourselves to be know can be based on reasoning from other things we take ourselves to know- at least, not if we rule out infinite regresses and circles. But why should that fact of logic (for that's what it seems to be) amount to a reason to think that knowledge is fragile? Most of us - including most philosophers and even most epistemologists - take it for granted that we know a great deal. I know that I just ate lunch; you know that there are people who write answers to questions on askphilosophers.org. More or less all of us know that there are trees and rocks and that 1+1 = 2 and that cheap wine can give you a headache. Some of the things we know call for complicated justifications; others don't call for anything other than what we see when we open our eyes or (as in the...

You're quite right: ordinary moral intuitions aren't infallible. However, the sort of criticisms you have in mind doesn't really suppose that they are. Start with an extreme case. Suppose someone came up with a moral theory with the consequence that most of our common moral beliefs were wrong. Now ask yourself: what sort of reason could we have to believe this moral theory? The point is that there's no possible way of making sense of this; perhaps there is. But if I'm told that my ordinary moral judgments are massively wrong, there would be a real problem about what sort of reason we could have to accept the very unintuitive theory from which that consequence flowed. Or take a more concrete example. Suppose some moral theory had the consequence that wanton cruelty toward innocent people was a good thing. I don't know about you, but I find it hard to imagine what could possibly make this moral theory more plausible than my ordinary moral belief that wanton cruelty is very wrong indeed. ...

One sure way to prove invalidity is to describe a possible case where the premises of an argument are true and the conclusion false. To make things a bit more plausible, let's change the example slightly. The following is valid: "q, not-p implies not-q, therefore p" I pick this example because this argument (closely related to modus ponens ) is one that people have a little more trouble seeing, or so my experience teaching logic suggests. So there could be and likely are cases where a person judges that q, and judges that not-p implies not-q, but has trouble with the logical leap and therefore fails to judge that p. That's a counterexample to the argument you're interested in. We have someone who judges the premises of a valid argument to be true but doesn't judge the conclusion to be true. This isn't surprising. To judge something is (putting it a bit crudely) to be in a certain state of mind toward it. Being in the "judges that" state of mind toward the premises of an...

It's a recurring question, and various versions of it make their way into arguments for God's existence. For the moment, I'll just raise one obvious worry (not original to me.) Let's agree that human life is extraordinary. If we assume that this calls for divine explanation, we run the risk of positing a being who is at least as extraordinary as we are, and therefore at least as much in need of explanation. But in that case, we seem either to be set upon an infinite regress or else it isn't clear that we had to take the first step in the first place. This hardly settle the question of whether there's a God (I'm taking that to be what you men by Higher Power.) But it does point out that some arguments for God's existence are too simple and too quick.

Thanks for a few moments of idle amusement! Perhaps the best response is "Oy!" But to earn the huge salary in Merely Possible Dollars that the site pays me, a bit more is called for. So yes: it's a case of false analogy, and the analogy goes bad in indefinitely many ways. But one of them has at least some intrinsic logical interest. Suppose that as a matter of social policy, we set up a system that left everyone with a paycheck of the same size at the end of every month. What does that amount to? It amounts to saying that each person can acquire the same quantity of goods as each other person. Maybe that would be a bad idea; maybe the result would be that people would get lazy and less wealth would end up getting produced overall. But that's not built into to very logic of the idea. It's an empirical claim, even if a highly plausible one. There's nothing logical incoherent, as it were, about a system intended to produce completely uniform distribution of wealth, whatever the practical...

Voluntarists say just that: God can make contradictions true. And if someone is really prepared to say that contradictions might be true, it's not exactly clear -- to me, at least -- how to answer. But I'll confess that I've never understood the pull of this solution. Here's a way of getting at what bothers me. Suppose, to see if it could make sense, that there's an omnipotent God. (Our goal is to see if the concept is coherent; not whether it fits any actual thing.) Suppose we have a computer screen with 1280 x 720 pixels. (Let them simply be on or off; ignore color.) Suppose we ask God to turn a set of pixels on so that there's a circle on the screen. (We have to allow for a certain amount of approximation, but that won't affect the real point here.) God can easily do that. (So can anyone with a good Paint program.) Now suppose we ask God instead to arrange pixels so that there's an equilateral triangle on the screen. Once again, no difficulty. But now suppose we set God a third task: turn...