Albert Barnes Commentary John 9:18-19

"The Jews therefore did not believe concerning him, that he had been blind, and had received his sight, until they called the parents of him that had received his sight, and asked them, saying, Is this your son, who ye say was born blind? How then doth he now see?" — John 9:18-19 (ASV)

Is this your son? The Pharisees proposed three questions to the parents, by which they hoped to convict the man of falsehood.

1. Whether he was their son?
2. Whether they would affirm that he was born blind?
3. Whether they knew by what means he now saw?

They evidently intended to intimidate the parents, so that they might give an answer to one of these questions that would convict the man of deception. We see here the cunning people will resort to rather than admit the truth. Had they been half as much disposed to believe on Jesus as they were to disbelieve, there would have been no difficulty in the case. And so with all people: were they as much inclined to embrace the truth as they are to reject it, there would soon be an end of cavils.