Since you asked, Walter, no, you are not a heretic, but
Walter Sandell. … I wonder if I’m a heretic for believing in, and supporting, the ordination of women. I would be a hypocrite if I kept silent about this issue …
I don’t know (and it doesn’t matter) who “Walter Sandell” is, but his pointed-yet-polite question (posted in a combox following Mary Ann Walsh’s recent unfocused essay in America) deserves a pointed-yet-polite (and of course, accurate) answer, so here it is: No, Walter, you are not a heretic for “believing in, and supporting, the ordination of women” but you do seem opposed to the teaching of the Church. That’s bad, to be sure, but it’s a different kind of bad.
In order to be a “heretic” one must, among other things, obstinately deny or doubt “some truth which is to be believed by divine and Catholic faith” (c. 751). Such truths are understood as being “contained in the word of God”, and as “divinely revealed”, and as pertaining “to the one deposit of faith” (c. 750 § 1). The point to grasp, though, is that heresy and the consequences of heresy (chiefly excommunication per c. 1364) arise only in the context of matters proposed for belief.
But the Church’s refusal to extend priestly ordination to women is not, at least not according to the flagship document dealing with this question, John Paul II ap. lit. Ordinatio sacerdotalis (1994), proposed as requiring that Catholics accord belief (credenda) to the assertion that “the Church has no authority whatsoever to confer priestly ordination on women”, but rather, as requiring that Catholics definitively hold (tenenda) that the Church has no such authority. The difference is important.
That the Church can impose for definitive adherence by the faithful some assertions that do not demand belief does not imply that some truths are “less true” than others, but rather, that some truths, though not revealed by God, are nevertheless so important for the support of revealed truths that they, too, must be able to be known and proclaimed with certainty. This notion of a “hierarchy of truths” is reflected in Canon 750—a norm that is just the tip of a magisterial iceberg—but, fascinating as exploring that might be, to answer Walter’s specific question about whether he is a heretic, one need only realize that the assertion in Ordinatio does not require belief and so its rejection cannot be “heresy”.
That said, even though Walter would ‘walk’ on a heresy charge, he seems to reject a proposition that is “to be held definitively” and therefore he seems “opposed to the doctrine of the Catholic Church.” Thus, assuming satisfaction of some other canonical elements of the crime, Walter seems at risk of committing a delict punishable under Canon 1371, 1° not with excommunication, I grant, but still by a “just penalty”. Even in an age in which one cannot imagine ecclesiastical authority taking action against him for having published his opposition to Church teaching in this area, Walter should reconsider his opposition to that teaching, and, at the very least, refrain from proclaiming it publicly.