What is Hawthorne saying about the problem of sin and human responsibility in Chapter 20 of The Scarlet Letter?What is Hawthorne saying about the...

The major point that Hawthorne is making about the problem of sin and human responsibility in describing the change in Dimmesdale's behavior is that once an individual has given in to sin, he is open to a host of more temptations.  Hawthorne says,

"Tempted by a dream of happiness, he had yielded himself with deliberate choice, as he had never done before, to what he knew was deadly sin.  And the infectious poison of that sin had been thus rapidly diffused throughout his moral system".

Having decided to forsake his calling and flee with Hester to start a new life with her in England, where no one would know or condemn them, Dimmesdale is seized by a euphoria which is deceiving.  Although he has been "lent...unaccustomed physical energy", he is beset by temptation after temptation; "at every step he was incited to do some strange, wild, wicked thing or other, with a sense that it would be at once involuntary and intentional, in spite of himself".  It is only by relying on his "natural good taste, and...his buckramed habit of clerical decorum", that he prevents himself from succumbing to the inexplicable forces that seem to be leading him to do more wrong.  Hawthorne is saying that sin leads to more sin.  The sense of power and giddiness that comes with having chosen the path of sin is illusive and temporary, only "lent", and the spirit is left much weakened by the choice in the face of further temptation; the ability to act with moral responsibility is much compromised.

A second problem presented by sin is that it forces an individual to lie in order to conceal it, creating "earth's heaviest burden", that of guilt.  Concealed sin forces dishonesty, in Dimmesdale's case, creating "a subtle disease that had long since begun to eat into the real substance of his character".  Hawthorne states that

"No man for any considerable period can wear one face to himself and another to the multitude without finally getting bewildered as to which may be the true".

Dimmesdale is indeed increasingly more unable to distinguish what is "real" and what is "a dream", and Hawthorne points out as an example of his declining ability to think and act responsibly his pitiable behavior in hoping to leave a good impression on his congregation through his Election Sermon despite the fact that he has already consciously chosen to follow the way of sin (Chapter 20).