nouns - Is literature as in 'the literature' singular or plural

When referring to literature in the sense of academic literature or philosophical literature I have sometimes heard people use the noun as if it were similar to the word 'people.' For example: 'The literature have confirmed this hypothesis.' I have also heard people use the noun as if it were singular (e.g. 'The literature has confirmed this hypothesis.'

Is there one usage that is more acceptable/correct in formal writing?