Martin was wondering whether I had missed the mark on Hamlet in what I said above. He might be right; the stage having been set with the murder of Hamlet's father, a crime which Hamlet could not prove, was there really any way to avoid a tragic ending? I don't know.
That Hamlet's tragic flaw is indecision, procrastination, or vacillation is also disputed by critics. The main argument in support of that conclusion comes from a well known public lecture by the Romantic poet Samuel Taylor Coleridge;
Man is distinguished from the brute animals in proportion as thought prevails over sense: but in the healthy processes of the mind, a balance is constantly maintained between the impressions from outward objects and the inward operations of the intellect;—for if there be an overbalance in the contemplative faculty, man thereby becomes the creature of mere meditation, and loses his natural power of action. Now one of Shakespeare's modes of creating characters is to conceive any one intellectual or moral faculty in morbid excess, and then to place himself, Shakespeare, thus mutilated or diseased, under given circumstances. In Hamlet he seems to have wished to exemplify the moral necessity of a due balance between our attention to the objects of our senses, and our meditation on the workings of our minds,—an equilibrium between the real and the imaginary worlds. In Hamlet this balance is disturbed: his thoughts, and the images of his fancy, are far more vivid than his actual perceptions, and his very perceptions, instantly passing through the medium of his contemplations, acquire, as they pass, a form and a colour not naturally their own. Hence we see a great, an almost enormous, intellectual activity, and a proportionate aversion to real action consequent upon it, with all its symptoms and accompanying qualities. This character Shakespeare places in circumstances, under which it is obliged to act on the spur of the moment:—Hamlet is brave and careless of death; but he vacillates from sensibility, and procrastinates from thought, and loses the power of action in the energy of resolve. Thus it is that this tragedy presents a direct contrast to that of Macbeth; the one proceeds with the utmost slowness, the other with a crowded and breathless rapidity.
The effect of this overbalance of the imaginative power is beautifully illustrated in the everlasting broodings and superfluous activities of Hamlet's mind, which, unseated from its healthy relation, is constantly occupied with the world within, and abstracted from the world without,—giving substance to shadows, and throwing a mist over all common-place actualities.
It is possible to accept Coleridge's presupposition that there is a tragic flaw, but find that flaw in something else: an Oedipal complex, pride or hubris, etc.
It is also possible to approach the text without reference to any tragic flaw, as such. But I think Coleridge's view has become predominant.