"My body, my choice" is well known slogan from those who oppose laws that limit a woman's right to an abortion. Yet, the idea that a woman has a right to do what she wants to her body seems to have disturbing consequences. If a woman drinks too much alcohol or takes too many drugs then her baby will suffer the consequences. That child will then suffer many challenges in life because of his mothers supposed right to do what she wants with her body. Yet when I point this out to people they get angry and insist that I want to limit women's rights. In fact it makes me angry that anyone would disagree with the idea that a woman shouldn't be morally and legally responsible for the incalculable harm she can do to her baby by poisoning her fetus. I can grant that there are exceptions such as prescription medications but otherwise isn't the idea that women can't be held responsible for doing damage to a fetus that will then suffer after being born just a very extreme position even if its a popular belief? And I...

I'm no lawyer, but I believe that the courts in some U.S. jurisdictions allow a child to sue its mother for lasting harm she caused the child while it was in utero . (Here I'm assuming that the child is identical to something that was once in utero , an assumption not everyone will grant.) I don't know whether the plaintiff has ever prevailed in such a lawsuit. In any case, if someone can be assigned civil liability for causing such harm, then it's not a huge leap to hold her morally responsible for it as well. My sense as a non-expert is that the courts are still struggling with this legal issue, so it's an important time for philosophers to weigh in on the issue and thereby perhaps help the courts decide it wisely and justly.

Euclid in "Elements" wrote that "things which equal the same thing also equal one another." Is this true in all cases? I've read that it is only true for "absolute entities," but not to "relations," although I do not understand this exemption. Are there any examples of things that are equal to the same thing but not to one another? Are relations really exempt from Euclid's axiom, and if so, why?

If by the adjective "equal" Euclid means "identical in magnitude" (which I gather is what he does mean), then his principle follows from the combination of the symmetry of identity and the transitivity of identity . The symmetry of identity says that, for any x and y , x is identical to y if and only if y is identical to x . The transitivity of identity says that, for any x , y , and z , if x is identical to y and y is identical to z , then x is identical to z . Therefore, Euclid's principle has exceptions only if the symmetry of identity sometimes fails or the transitivity of identity sometimes fails. But I don't think either of them ever fails. Now, some relations that are similar to the identity relation aren't transitive. I might be (1) unable to tell the difference between color swatches A and B, (2) unable to tell the difference between swatches B and C, yet (3) able to tell the difference between swatches A and C. But...

How do you know that you are sure that your parent are your parents?

Your question asks about your knowledge of your own certainty : "How do you know that you are sure...?" That's a question about your knowledge of your own mind rather than about your knowledge of your parentage. So I think the best answer is "By introspection -- by looking inward -- and perhaps also by examining your own behavior for signs that you're unsure that the people you take to be your parents are in fact your parents." If, instead, you meant to ask how you can be sure that the people you take to be your parents aren't impostors, then you might have to seek DNA evidence (in the case of biological parents) or adoption records and other documents (in the case of adoptive parents). There's also a facetious answer: "Of course your parents are your parents -- that's a tautology!"

I am confused about how a conditional statement is necessarily true, and not false or unknown, when the antecedent and consequent are both false. According to the truth table, the sentence "If Bill Clinton is Cambodian, then George Bush is Angolan" is true. How can such an absurd sentence be true? It seems initially like the sentence could just as easily, or more easily, be false or unknown.

The truth-table for the material conditional says that any material conditional with a false antecedent is true. If we construe the conditional you gave as a material conditional, then (because it has a false antecedent) it comes out true. But the material conditional doesn't come out necessarily true unless it's not just false but impossible that Clinton is Cambodian (or else it's necessarily true that Bush is Angolan) . The material conditional has the advantage of being tidy, and a true material conditional will never let you infer a falsehood from a truth. Still, for the reason you gave (and for other reasons too) many philosophers say that the material conditional does a bad job of translating the conditionals we assert in everyday language. You'll find lots more information in this excellent SEP entry .

I am learning about the principle of noncontradiction ~(p^~p). I can see that this would work if we assume that 'p' can only be true or false. Why should I make this assumption. I can see a lot instances where we need more than 2 truth values (how people feel about the temperature of a room, for instance could have an infinite number of responses, and all would be true because the proposition is based on subjective experiences). What is this type of logic called? If this is a possible logic then can't someone argue that everything is this way?

Your example about the room temperature doesn't seem to support the idea that we need more than two truth-values, because you classify everyone's responses as true . Instead, the example raises the question of how to interpret the people in the room: as disagreeing with each other because they're making incompatible claims ("It's cold"; "It's not cold") or as only apparently disagreeing with each other because they're making compatible claims ("It feels cold to me"; "OK, but it doesn't feel cold to me "). Standard logic (often called "classical" logic) has just two truth-values. Many-valued logics are nonstandard logics that contain anywhere from three to infinitely many truth-values -- in the latter case, all of the real numbers in the closed interval [0,1], with '0' for 'completely false' and '1' for 'completely true'. You'll find lots of detailed information in this SEP entry .

Is philosophy about the world or is it just about our concepts and the way we use them? Or both?

I agree: both. There seems to me to be a false dichotomy between "the world" and "our concepts and the way we use them": our concepts and the way we use them are surely part of the world.

I know affirming the consequent is a fallacy, so that any argument with that pattern is invalid. But what what about analytically true premises, or causal premises? Are these not really instances of the fallacy? They seem to take its form, but they don't seem wrong. For example: 1. If John is a bachelor, he is an unmarried man. 2. John’s an unmarried man. 3. Therefore he’s a bachelor. How can 1 and 2 be true, and 3 be false? Yet it looks like affirming the consequent. 1. X is needed to cause Y. 2. We’ve got Y. 3. Therefore there must have been X. Again, it seems like the truth of 1 and 2 guarantee the truth of 3. What am I missing?

You asked, "How can 1 and 2 be true, and 3 be false?" Suppose that John is divorced and not remarried; he'd be unmarried but not a bachelor. You can patch up the argument by changing (1) to (1*) "If John is a bachelor, he is a never-married man" and changing (2) to (2*) "John is a never-married man." The argument still wouldn't be formally valid, which is the sense of "valid" that Prof. George uses in his reply. But it would be valid in that the premises couldn't be true unless the conclusion were true, because (2*) by itself implies that John is a bachelor. An argument that isn't formally valid -- i.e., an argument whose form alone doesn't guarantee its validity -- can be valid in the sense that the truth of its premises guarantees the truth of its conclusion. The last sentence of Prof. George's reply suggests that definitions are crucial in enabling conclusions to follow from premises. I think that suggestion is true only if logical implication is a relation holding between items of...

I've recently read that some mathematician's believe that there are "no necessary truths" in mathematics. Is this true? And if it is, what implications would it have on deductive logic, it being the case that deductive logical forms depend on mathematical arguments to some degree. Would in this case, mathematical truths be "contingently-necessary"?

Your question is tantalizing. I wish it had included a citation to mathematicians who say what you report them as saying. On the face of it, their claim looks implausible. Are there no necessary truths at all? If there are necessary truths, how could the mathematical truth that 1 = 1 not be among them? One way to hold that mathematicians seek only contingent truths might be as follows. If some philosophers are correct that propositions are to be identified with sets of possible worlds, then there's only one necessarily true proposition, because there's only one set whose members are all the possible worlds there are. That single necessarily true proposition (call it "T") will be expressed by indefinitely many different sentences , including the sentences "1 = 1" and "No red things are colorless," and it will be contingent just which sentences express T. On this view, mathematicians don't try to discover various necessary truths, since there's just one necessary truth, T. ...

Pages