In reality there is no kind of evidence or argument by which one can show that Shakespeare, or any other writer, is "good". Nor is there any way of definitely proving that-for instance-Warwick Beeping is "bad". Ultimately there is no test of literary merit except survival, which is itself an index to majority opinion.
Good name in man and woman, dear my lord,
Is the immediate jewel of their souls:
Who steals my purse steals trash; ’tis something, nothing;
’twas mine, ’tis his, and has been slave to thousands;
But he that filches from me my good name
Robs me of that which not enriches him,
And makes me poor indeed.