Is all behaviour learned?

As commonly understood and reinforced here, 2 + 2 = 4 is taken as meeting the test for absolute certainty. This appears to be true in a formal or symbolic sense but is it true in reality? When we count two things as being the same and add them to two other same things do we really get four identical things? Perhaps, perhaps not; it may depend on one's identity theory. Do we know with absolute certainty when we have one thing and not two? What am I missing?

One of the most common justifications I hear for abortion is "a woman should have control over her body." If humans reproduced oviparously, would that change the debate? Let's say a woman conceives a child, and then immediately lays an egg. The egg would still need incubation and maintenance, though this could be performed by any party, not just the mother. After nine months of development, the egg would hatch into a baby human. Would a woman be justified in crushing this egg? This mimics the abortion debate, except that in this case the fetus cannot be addressed as part of the woman's body. Would that invalidate any abortion arguments?

Why is it that very religious people tend to be kinder and more compassionate (with a few notable exceptions to people they deem unworthy i.e.: homosexuals) than secular people? Is this evidence that we need religion/should be religious?

Abraham Lincoln once made this argument that white people have no right to enslave black people: "You say A. is white, and B. is black. It is color, then; the lighter, having the right to enslave the darker? Take care. By this rule, you are to be slave to the first man you meet, with a fairer skin than your own." If I understand Lincoln correctly, he is arguing that because some white people have darker skin than other white people, skin color is not sufficient justification for slavery. Isn't this a fallacious conceptual slippery slope argument? Let's say we have three men. The first has only a few dollars, the second is a multi-millionaire, and the third is a billionaire. The third one is richer than the second. But that does not change the fact the the first and second are both rich and the first is not. In the same way, it might be true that some white people have darker skin than others. But this doesn't change the fact that there are white people and black people (as well as borderline cases.) ...

How does the temperature ever change? If we assume that temperature is a continuous measurement, then we know that it has an infinite number of potential values. In order for temperature to transition between two values, it must then pass over the infinite set of values that lies between whichever two values the temperature is transitioning between. It now seems that temperature should not be able to change at all because before it may change to a given value, it must first reach a value between the desired and the current. Since we can make this claim infinitely, it would seem that temperature becomes "trapped", in a sense, at its current value, unable to change at all. Of course this problem can be applied to other concepts as well, and we might easily draw comparisons to Zeno's ancient thought experiment of Achilles and the tortoise. But the logic here is slightly different; the desired temperature is not continuously fleeing from the present as the tortoise is from Achilles. I simply raise the...

Is it normal after reading philosophical material to feel like you've been blind for some time of your life? I'm asking this because I was never interested in anything that had to deal with philosophy. After I read some philosophical material I felt like I didn't really know anything. Not only that, but my views on religion have changed. It's almost like I've lost my faith after I read some topics on philosophy. Is this normal or more of a personal experience?

What is the difference between mathematical logic and philosophical logic? Yes I know, one has more math than the other. Is Gödel's incompleteness in mathematical logic? Is modal logic in philosophical logic? Can you give other examples of different logics or questions each asks in order to distinguish the two?

American Protestant fundamentalists who are against abortion frequently say they are for a "culture of life." It seems that many of them also support the death penalty and have a low threshold for a willingness to wage war. Does anyone know how they justify this seeming contradiction? What is remarkable to me is that fundamentalist Christians who are against abortion seem to hold this value of "unborn life" above almost all else, saying that they are "single issue voters." Not only do I wonder how this is reconciled with their not seeming to value the lives of convicted criminals and those will die due to wars that we easily enter, but also how they put the value of a fetus' life above all the other things that Christians are supposed to value, that, if one is a single issue voter, one gives up fighting for. I guess what I mean is, how is this favoring of one class of lives justified philosophically/religiously against the valuing of other classes of lives and other "Christian" values? Thanks.

I have an old copy of whateleys logic (1840s) is it still worth reading?