Best Argument: Apple's fault
Ryan Naraine: To really understand Apple’s negligence on security, we have to go back to 2006 and that famous “Mac vs PC” commercial http://www.youtube.com/watch?
This perpetuates a false sense of security among the Mac faithful. Mac OS X users have the mindset that security is not important and this complacency leads to long delays in patching dangerous security flaws and responding to in-the-wild attacks.
This iBotnet (more than 685,000 infected Mac machines) is entirely Apple’s fault. The Java patch (CVE-2012-0507) was issued for Windows on February 14, 2012. This same vulnerability affected Mac OS X but Apple didn't provide a fix until April 3, 2012.
Apple left its users exposed for 49 days, providing a large window of opportunity for malware writers to build a botnet. Unforgivable.
Christopher Dawson: It's easy to blame Apple for the widespread infection of Macs with the Flashback Trojan. Actually, most would argue that Apple should be more proactive in anti-malware development; to date, this has taken a backseat to user experience. However, that lack of focus on security is as much (or more) the fault of naive users who blithely go on buying shiny new Macs and iOS devices, smug in their apparent invulnerability to rogue software as it is Apple’s.
Why has Windows evolved into a remarkably secure environment? Because the market first demanded and paid for powerful third-party software and then demanded native anti-malware solutions, again speaking with their wallets, by purchasing (ironically) Macs or running Linux. How many Mac users run antivirus tools on their machines even if only to prevent spreading Windows infections? Not many (says the debater writing this on his Mac running both Avast and ClamXav).