Ilya Somin in The Volokh Conspiracy:

William Saletan of Slate has an interesting article on Ted Cruz’s misrepresentations about his record on immigration. He effectively shows that Cruz supported the legalizing the status of large numbers of illegal immigrants back in 2013, but now pretends that he opposed it all along.

The truth is that deceiving voters about one’s past or present positions is a fairly standard political strategy. Few successful politicians become such without engaging in this kind of deception at one point or another. I see little difference between Cruz’s distortions of his record on immigration, and President Obama’s years of lying about his position on same-sex marriage between 2008 and 2012.

Obama’s bad behavior, of course, in no way excuses Cruz’s or that of other Republicans. Here, as elsewhere, political partisans would do well to try to keep their biases in check and remember the sins of their own party, as well as those of the opposition.

In fairness, Cruz, Obama and other similar political leaders could potentially justify their deceptions by pointing to the dangers of unilateral disarmament in political combat. If they stop engaging in politically convenient lying, their opponents probably will not, and the more ethical candidates will be at a disadvantage. Donald Trump, whom Cruz is battling for the Republican nomination, is the proud winner of Politifact’s 2015 Lie of the Year award. To say the least, it is highly unlikely that he would reciprocate any restraint on Cruz’s part. President Obama (who won the same award in the 2013), can cite the various deceptions perpetrated by his political opponents.

If, as is likely, Cruz truly believes that the public interest would be best served by his winning the presidency, he could also conclude that he is justified in using deception to try to achieve that goal – especially if his opponents are going to use similar tactics. Similarly, Obama likely believes that his lies about same-sex marriage and the Affordable Care Act also ultimately served the public interest by helping him get elected, and enabling him to push through various beneficial policies.

Americans have the politicians they deserve, as in, if we can’t keep track of their lies from one month to the next, they have no choice but to manipulate our ignorance, rational or otherwise.