Sure, such a case can be made. Let's suppose we view all three substances as detrimental to society. We can still argue that practically speaking once a substance has the very long history of legalization and has become entrenched into society the way alcohol and tobacco are (and marijuana is not) it is very difficult to simply outlaw it. Yet, we might take steps to discourage their use... for example, the USA has been quite successful in reducing the smoking rate through education campaigns and by adding excessive taxes on tobacco. All of this is perfectly consistent with saying we should not legitimize a third addictive detrimental substance like marijuana into society by legalizing it.

I think there are a number of problems with this form of violent protest. First, I don't see how this vandalism accomplishes anything positive. It doesn't help anyone. It doesn't punish BP. It doesn't conserve a single drop of oil. It doesn't draw attention to an unknown problem (anyone who doesn't know about the Gulf oil spill is living in a cave). At best, this energy is wasted and should have been used on more productive endeavors. Second, the violence is against a relatively innocent third party. The Gallery in no way causes BPs actions. They neither buy nor sell from them. Virtually nothing in the universe would be different if they had refused BPs donations. They are 'guilty' of accepting a gift. I seriously doubt there is anyone who thinks, 'well, the oil spill is terrible, but BP is a fine organization because they donate to Tate.' It is hard for me to see why 'accepting legal donations from an environmentally reckless company' would merit this style of violence. Third, this sort of ...

A traditional version of this puzzle is referred to as 'Buridan's ass'. It postulates that a donkey put equidistant between two identical stacks of hay might starve out of inability to choose between them. If reason says that they are equally qualified for the position and either will do just fine, then any (morally acceptable) arbitrary criterion would do. So, I would simply flip a coin. I don't think the puzzle shows anything disturbing about the limits of reason. After all, you merely stipulated that the candidates were identically qualified.

I think this kind of dilemma is rather common and has a fairly straightforward solution. When two people have very diverse interests it is important to learn to sincerely enjoy activities that your significant other enjoys. There's a difference between someone who is willing to 'tolerate' an activity towards which he is indifferent, which is the situation you are describing and someone who sincerely commits himself to discovering what it is about the activity that others find enjoyable. I've found that for most activities one is genuinely neutral towards (as opposed to activities one dislikes), it is possible to cultivate at least some genuine interest.... so my advice is learn to appreciate the significance of moving a football ten yards in four attempts, or the merits of Edward over Jacob, or why wine aged in oak barrels tastes better, etc.

I don't think the reality of the parent's serious illness and reduced lifespan in itself would make it morally wrong to reproduce. After all, there are plenty of children who grow up without ever meeting one of their parents or who lose one or both parents early in life that have a very fulfilling life on the whole. That being said I could imagine circumstances where I would encourage the parent not to reproduce. For example, if that family's specific circumstances would guarantee that the child would end up in utter poverty long-term after the parent's death. I don't think the 'potential harm of denying the other potential parent the chance to have a child' weighs too heavily in the decision. Clearly, you are either putting the future child in a circumstance that is likely to result in his/her overall flourishing or not. Your potential partner's harm of missing the chance to parent is a comparatively lesser matter since there are other ways that he/she might have the opportunity to flourish. ...

One of the most useful relational skills that one can cultivate is the ability to have nuanced moral evaluations of people. Few individuals are complete saints or monsters. Instead most of us are complex and flawed, yet praiseworthy on at least some points. So, I would say that it is wisest to love and respect your parent for his or her good treatment of you, but be outraged at the bad behavior. It takes wisdom to know how to live this attitude out well. The bad behavior may merit some confrontation from you, but you shouldn't simply cut off a relationship with someone who has treated you well.

I suppose there are sophisticated theologies that would take either of the options you suggest. Yet I think a third position is possible. Someone could claim that 'being open-minded' is a necessary but not sufficient condition for discovering God's existence. Perhaps, it requires some more aggressive effort or a step of faith to come to believe in God. There is considerable literature in philosophy of religion circles on 'The Problem of Divine Hiddenness' that asks (from the believer's viewpoint) why the existence of God is not more evident.

I think that the problem with that argument is that we can get nearly the same level of safety by sending the killer to jail for life. And given the imperfections of the justice system, there's a chance that we could execute an innocent person which is much worse than sending an innocent person to jail for a few years. Perhaps, if we were absolutely certain someone was guilty of murder and we had good reason to think that the death penalty had a significant deterrent value in preventing future murders it could be justified. But the deterrent value of the death penalty has been questioned in recent years.

I suppose it depends on what you mean by 'marketing'. Generally, I appreciate being informed about goods and services that I might be interested in purchasing. However, I hate being manipulated into buying things I don't really want or being misinformed about the products that I am offered. Unfortunately, I would have to say that a lot of 'marketing' these days seems to fall into the second unethical category.

Charles Taliaferro has a good point, but I feel the need to add that many intelligent religious thinkers who might be 'philosophically oriented' end up going to seminary or studying formal religion instead of going into philosophy. So, there are many attractive options open to an 'abstract thinking' religious person who wants to pursue in-depth metaphysical studies that atheists don't have. After all, if you are satisfied with relatively conventional religious answers there's no need to go into philosophy. I wouldn't read any more into the pattern than that. Finally, I'd note that the number of theists in philosophy is increasing rather than decreasing as Charles and I recently commented upon at length in another question.