Is a Virus the Single Single Cause of Illness?

Isay: There aren't simple, single causes for things. So there's not one thing that some people are doing that other people aren't. The interesting thing about these complex systems is you can't really just pull out one factor and say, well, it's really that. We all have more control over our brains. And that means we have more responsibility too. Isay: Even if we could explain the causeis, it doesn't necessarily mean that it lets people off the hook from being responsible.