I was referencing effective security (what your chances are of contracting something bad), not theoretical security (how inherently secure the system is or isn'

I was referencing effective security (what your chances are of contracting something bad), not theoretical security (how inherently secure the system is or isn't). You're effectively safer on a mac than Windows regardless of the design and architecture. It's just a fact that you have orders of magnitude less malware on the mac. So saying macs have "perceivably" better (effective) security than Windows is a bit like saying white is perceivably brighter than black. Technically true, but it sounds a tad dishonest to me (or maybe he was just talking about theoretical security).