[goodcanadian]

As someone who considers himself a scientist, though definitely not in the medical field, this is my take:

Alcohol (i.e. ethanol) is essentially a poison, but so are many other things that we regularly consume. Our bodies have evolved to handle small to moderate amounts of these naturally occurring poisons, so small to moderate amounts aren't really a problem.

It has been shown that there are side benefits to alcohol and/or other compounds commonly found in alcoholic drinks. From the articles I've seen, I believe these benefits to be real, but I'm less convinced that they are significant in the context of safe amounts of alcohol. It's all a trade off. I think this is why it remains controversial; there is not a clear answer.

So, it's almost certainly safe to consume small amounts of alcohol, but you are probably not losing anything if you don't. Consuming large amounts of alcohol, of course, is known to be bad.

[rossdavidh]

All sounds reasonable, but: 1) a small amount of a poison, like a fever, can be a net positive if it does more damage to pathogens than to you, and 2) if the social benefits of moderate amounts of alcohol are significant, given that we know the medical benefits of social ties are significant, alcohol could be a net bonus