President Obama gave a terrific speech Wednesday night. He movingly mourned and honored the victims of Saturday's senseless atrocity outside Tucson, comforted and inspired the country, and encouraged those of us who have the privilege of serving America. He encouraged every American who participates in our political debates - whether we are on the left or right or in the media - to aspire to a more generous appreciation of one another and a more modest one of ourselves.

The president appropriately disputed the injurious suggestion that some participants in our political debates were responsible for a depraved man's inhumanity. He asked us all to conduct ourselves in those debates in a manner that would not disillusion an innocent child's hopeful patriotism. I agree wholeheartedly with these sentiments. We should respect the sincerity of the convictions that enliven our debates but also the mutual purpose that we and all preceding generations of Americans serve: a better country; stronger, more prosperous and just than the one we inherited.

We Americans have different opinions on how best to serve that noble purpose. We need not pretend otherwise or be timid in our advocacy of the means we believe will achieve it. But we should be mindful as we argue about our differences that so much more unites than divides us. We should also note that our differences, when compared with those in many, if not most, other countries, are smaller than we sometimes imagine them to be.

I disagree with many of the president's policies, but I believe he is a patriot sincerely intent on using his time in office to advance our country's cause. I reject accusations that his policies and beliefs make him unworthy to lead America or opposed to its founding ideals. And I reject accusations that Americans who vigorously oppose his policies are less intelligent, compassionate or just than those who support them.

Our political discourse should be more civil than it currently is, and we all, myself included, bear some responsibility for it not being so. It probably asks too much of human nature to expect any of us to be restrained at all times by persistent modesty and empathy from committing rhetorical excesses that exaggerate our differences and ignore our similarities. But I do not think it is beyond our ability and virtue to refrain from substituting character assassination for spirited and respectful debate.

Public life has many more privileges than hardships. First among them is the satisfying purpose it gives our lives to make a contribution to the progress of a nation that was conceived to defend the rights and dignity of human beings. It can be a bruising business at times, but in the end its rewards are greater than the injuries sustained to earn them.

That doesn't mean, however, that those injuries are always easy to slough off and bear with perfect equanimity. Political leaders are not and cannot reasonably be expected to be indifferent to the cruelest calumnies aimed at their character. Imagine how it must feel to have watched one week ago the incomprehensible massacre of innocents committed by someone who had lost some essential part of his humanity, to have shared in the heartache for its victims and in the admiration for those who acted heroically to save the lives of others - and to have heard in the coverage of that tragedy voices accusing you of complicity in it.

It does not ask too much of human nature to have the empathy to understand how wrong an injury that is or appreciate how strong a need someone would feel to defend him or herself against such a slur. Even to perceive it in the context of its supposed political effect and not as the claim of the human heart to the dignity we are enjoined by God and our founding ideals to respect in one another is unworthy of us, and our understanding of America's meaning.

There are too many occasions when we lack that empathy and mutual respect on all sides of our politics, and in the media. But it is not beyond us to do better; to behave more modestly and courteously and respectfully toward one another; to make progress toward the ideal that beckons all humanity: to treat one another as we would wish to be treated.

We are Americans and fellow human beings, and that shared distinction is so much more important than the disputes that invigorate our noisy, rough-and-tumble political culture. That is what I heard the president say on Wednesday evening. I commend and thank him for it.

The writer, a senator from Arizona, was the 2008 Republican nominee for president.