Our very smart son-in-law pointed out that the idea of a corporation as a person is enshrined in federal law, but he also provided a quote from Thomas Jefferson that indicated his concerns about the role of corporations in this nation:
I hope we shall... crush in its birth the aristocracy of our moneyed corporations which dare already to challenge our government in a trial of strength, and bid defiance to the laws of our country.
Even though I am wrong in my inclination to refuse to give corporations the rights of persons, I think I'm right that the speech which is protected under the Constitution is primarily public speech and that the protection is not absolute. Private speech generally needs no protection and it is the right to speak in the public square that needs protection. But protected speech doesn't mean speech without consequences. Just as the private speech of a child who swears at his parents will certainly have consequences, so the public speech of persons or corporations should not be without consequences. Target, in its support of a pro-business candidate who opposes gay marriage, has learned that its protected speech may have serious consequences. Will I be willing to continue shopping at Target? I haven't decided yet, but losing customers is a possible consequence of that protected speech.
The framers of the Constitution and the Bill of Rights were not, I believe, concerned to protect anonymous speech. Corporations, given the recent Supreme Court decision, are free to speak by supporting political candidates, but I believe that that speech should not be anonymous.