A polite substitution for "lamer"

Is there a polite word that can be used to designate someone who didn't really understand what he or she was doing? Or, in general, someone who is intentionally ignorant of how things work. A "lamer" doesn't fit for being impolite, and seemingly harming some people's ears too much.

Edit: Another good definition is

It distinguishes between people who are ignorant by chance from those who are ignorant by choice.

And it makes me think that there is no polite substitution just because the meaning itself being impolite and abusive. Right?

Novice? Unaware of [whatever]? Edit: A self-appointed expert?

The problem is that implying that someone intentionally ignorant of something is inherently discourteous. All of the polite variants you'll find will be implying that the ignorance is unintentional.

Shamelessly copied and pasted from NOAD:

Someone who knows nothing about growing things might be called ignorant by a farmer who never went to high school but has spent his life in the fields. Although all of these adjectives refer to a lack of knowledge, ignorant refers to a lack of knowledge in general (: a foolish, ignorant person) or to a lack of knowledge of some particular subject (: ignorant of the fine points of financial management).

A professor of art history might refer to someone who doesn't know how to look at a painting as uneducated or untutored, both of which refer to a lack of formal education in schools (: she was very bright but basically uneducated, and completely untutored in the fine arts).

Someone who cannot read or write is illiterate, a term that may also denote a failure to display civility or cultivated behavior (: the professor routinely referred to his students as illiterate louts).

Someone who is unlettered lacks a knowledge of fine literature (: a scientist who was highly trained but unlettered); it also implies being able to read and write, but with no skill in either of these areas.

Unlearned is similar to ignorant in that it refers to a lack of learning in general or in a specific subject (: an unlearned man who managed to become a millionaire), but it does not carry the same negative connotations.

Uninformed refers to a lack of definite information or data. For example, one can be highly intelligent and well educated but still uninformed about the latest developments in earthquake prediction.

If you want to be nice, you can say the person is a neophyte. Less polite would be philistine, which MW defines as "one uninformed in a special area of knowledge." If this is a technology-related field, luddite might work (though it's not very nice, either). A more neutral way of saying "intentionally ignorant" might be

exhibits a deliberate lack of sophistication about _.

EDIT: Understanding the question better now, I offer another option to describe someone who is arrogantly and intentionally ignorant yet insists on trying to instruct others.

insists on [spreading or infecting others with] his deliberate lack of sophistication about _.

This assumes you're just looking for a polite way to describe the problem to third parties. You wouldn't say this to the person's face -- at least not if you expect to get along with him afterward. :)

Sorry so many words. I don't think there's a way to say this that is both concise and diplomatic.

A polite way to say that a person doesn't know something:

[Person] is not familiar with [something].

For example,

Mark is not familiar with Java programming.

A few words that can mean "ignorant by choice" (with mixed amounts of tactfulness):

• unenthusiastic
• unmotivated
• lackadaisical
• bored
• resistant
• rebellious
• apathetic
• uninterested
• ennui
• listless
• passionless
• indifference