I agree, this is also mentioned somewhere in one of the last slides.

As a designer I know about MySQL, the terminal, PHP, Javascript, jQuery, RoR, Sass, HTML, CSS etc.; if a developer knows the basics about color, typography and alignment and knows why the designer in his team does the things he/she does it's probably going to be much easier working together.

Good point. I hadn't actually considered that angle.

I tend to get instinctively defensive when people from other professions make assumptions about mine based on a limited understanding.

Just as is the case with many things, ability comes with experience. Design, while dealing with many concrete and quantifiable considerations, still relies heavily on a distinguishing and trained eye. It's what separates the Jakob Nielsens ( almost entirely intellectual in approach ) and marketable attractive design.

Well, the more knowledge an individual has in an area, the more likely they are to realise their shortcomings.

It can also create a false sense of understanding...“A little bit of knowledge is a dangerous thing.”

Anyone care to explain their downvote?

I left your comment unmolested, but I'd guess because of the aphorism? There's something fundamentally lazy about appealing to them... :P

I didn't bother to cite it before, but there's a pretty well known study in this area: http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect