An attitude has to do with position. This can be either a position of the body (“attitude of attentiveness”), or of an aircraft, whether it is say nose-up or nosedown. Or “attitude” can mean a position of mind and belief (“attitude of denial”, “attitude towards capital punishment”).
Of late, however, we have been witnessing the emergence of a new, and now probably more common, meaning of “assertive personality”. This is another Americanism. The new “attitude” is no longer a neutral orientation of ideas, where we needed an adjective to say what kind of an attitude was involved (“a positive attitude”, “a negative attitude towards racist language”).
The new meaning of “attitude” doesn’t have a plural. It is usually “with attitude”, or “have an attitude”. One type is seen in “the salesperson must have had a bad day and was full of attitude”. This means that he was truculent, obdurate, even aggressive. This sense of “attitude” is negative, quite strong, and has an unpleasant effect on the person on the receiving end.
A second and more general type of “attitude” is not so negative. It means something like “strong personality, clearly expressed”. As in: “My daughter brought home a new cat. This is one feline with attitude.”
Such a cat – I now write from recent experience – stamps around the house and yells. It’s a Siamese. It has personality. It has wants and needs, and it makes them felt when and how it likes. There is no doubt that it has attitude. A surfeit of it. Or I might say to a vehement friend: “Try toning down the attitude. You’re coming over too strong”.
You can have an “attitude problem” and you can “cop a lot of attitude”. That would make no sense with the original meaning.
With a bit of imagination we can speculate how this shift of meaning and usage could have come about. “I don’t like your attitude” is the old meaning. But it implies both that the person with the attitude is expressing it strongly, and that the person exposed to that attitude doesn’t like it.
From there it’s not a big step to “attitude” being taken as “strongly expressed orientation and behaviour”.
Public figures these days thrive on “attitude”. It helps provide a sense of identity and to get people to listen. Modesty and shrinking violets don’t sit easily with modern attitude.