capitalization - Why does binomial nomenclature seem to break case rules?

According to the Wiki page for binomial nomenclature, we are supposed to capitalize the first word when naming species regardless of where it occurs in the sentence. To me, this seem very incongruous with not only the English language but all languages that I know of which use Latin characters. So what is the justification for this (if any)?

For example, I have a house cat but my biology teacher has a Felis catus.

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I see where people may be having trouble with this now. I don't know if this is a rule or not but I can find no other real examples of capitalization being used like this. virmaior has shown me that there is a seldom used rule about Platonic forms which would apply if creatures where forms. That is not the case (they have actual bodies and so on) but perhaps that really is the best answer as incorrect as it may be.

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Oldcat has brought up an interesting point below:

Felis is the proper name of the genus, not of any particular cat. We do capitalize breeds of cats, like Persian and American Curl, because they are the proper name of the group.

This is similar to points made by a few others and may be related to Platonic forms. I'm still not seeing what would make the less specific term Felis catus capitalized while the more specific term catus by itself isn't (aside from the seemingly arbitrary explanation that Felis catus is a Platonic form while catus alone isn't)? Unfortunately, the fact that we then again begin capitalizing the even more specific breed name only confuses the issue further. Do you see my point?

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It occurs to me that there may be multiple answers to this. In scientific technical writing it could be proper to use Felis catus and in common usage it may be more proper to simply use felis catus (or possibly Felis Catus but not Felis catus because that would be a ridiculously arbitrary rule for a common language). It isn't lost on me that a very similar idea has been mentioned several times but the difference is that here I'm accepting that these terms have, in fact, become part of the English language while rejecting binomial nomenclature as part of the English written language. Is that a common consensus? If it is then shouldn't there be a general rule about this instead of a bunch of specific cases where groups are considered proper nouns in some cases and improper nouns in others?

Answer

While it's not really a matter of English choice since it's decided by international standard (see Frank's comment above), I think the base justification was originally a philosophical statement, viz., that a species is a Form (where Form here means Platonic form or Aristotelian essence). See for instance here.

By convention, in philosophy, these were/are capitalized -- a capitalization rule that was once common in English (e.g., capitalizing Justice when it refers to what we might now call justice proper or justice itself). You can see this usage in Locke (though it also is an oddity in English capitalization).