I've wanted to write this blog for a long time, but never gotten around to it. It's a very simple observation, but one that too many people fail to make. Maybe something will come of it :-)
Oftentimes you will see something like the following on a web news site:
Headline: New security bug found in Windows
Poster A: Windows sucks!
Poster B: Windows is attacked more often because it has the highest market share
Poster C: If that were true, Apache would be attacked more often than IIS
Of course, C's unstated-but-obvious assumption is that Apache is not attacked more often than IIS, even though it has a higher market share.
If C is right, he has disproved B's assumed premise about market share based on a valid form of argument known as modus tollens -- P implies Q, but Q is false, therefore P must be false.
The trouble though is that C is actually enforcing B's argument, since Apache is attacked far more often than IIS. Of course, C hasn't proved B's argument, he just hasn't disproved it either. (To assume that C had proved B's argument would be a logical fallacy known as affirming the consequent -- P implies Q, and Q is true, therefore P is true).
Note: For the purposes of this entry, I have ignored two things because they are not relevant to the discussion: The first is the debate about what web server market share numbers actually mean, the second is the question of why the sites were attacked (software bugs, 3rd party installs, poor administration, etc.). I merely wanted to show that C does not disprove B, not that B is necessarily correct.