Aleksandr Kogan, the academic who was hired by Cambridge Analytica to harvest information from tens of millions of Facebook profiles, defended his role in the data collection on Sunday, saying he was upfront about how the information would be used and that he “never heard a word” of objection from Facebook.

Yet Mr. Kogan, 28, a psychology professor who has found himself cast as the villain by both Cambridge Analytica and Facebook, expressed regret for his role in the data mining, which took place in 2014.

“Back then, we thought it was fine. Right now my opinion has really been changed,” he said.

“I think that the core idea we had — that everybody knows, and nobody cares — was wrong,” Mr. Kogan added. “For that, I am sincerely sorry.”

Since the full scope of Cambridge Analytica’s data collection was revealed last month by The New York Times, both Facebook and Cambridge, a political data firm, have been under intense scrutiny and eager to shift the blame to Mr. Kogan.

They have said that he misled them about how the information was being collected and what it was being used for. Facebook has even banned Mr. Kogan from the social network and deleted his profile.

But in his first extensive interview since the report in The Times, Mr. Kogan insisted that he was upfront about the Facebook app used to harvest the data, and that no one seemed to care.

“The belief in Silicon Valley and certainly our belief at that point was that the general public must be aware that their data is being sold and shared and used to advertise to them,” Mr. Kogan said in an interview with “60 Minutes” on Sunday.

Founded by Stephen K. Bannon and Robert Mercer, a wealthy Republican donor, Cambridge Analytica rose to prominence for its work with President Trump’s campaign in the 2016 election. The company claimed it had developed analytical tools that could identify the personalities of American voters and influence their behavior — and that Facebook data had been used to help create so-called psychographic modeling techniques.

The techniques have been widely questioned by academics and other political data firms, and Cambridge Analytica has since insisted that the Facebook data was not used in its work in the 2016 campaign.

Mr. Kogan was hired on a contract by Cambridge Analytica in June 2014 — the same month the company was founded — and harvested the data throughout the summer by asking Facebook users to take a lengthy personality questionnaire.

The questionnaire was not actually on Facebook. It was hosted by a company called Qualtrics, which provided a platform for online surveys. Respondents were asked to authorize access to their Facebook profiles, and when they did, an app built by Mr. Kogan performed its sole function: harvesting the data of users and all of their Facebook friends. Their names, birth dates and location data, as well as lists of every Facebook page they had ever liked, were downloaded without their knowledge or express consent.

Facebook has said that those who took the quiz were told that their data would be used only for academic purposes, claiming that it and its users were misled by Cambridge Analytica and Mr. Kogan. Cambridge Analytica has said it was told that Mr. Kogan’s app complied with Facebook’s own rules.

But The Times reported last month that the fine print accompanying Mr. Kogan’s questionnaire told Facebook users that their data could be used for commercial purposes. That was an outright violation of Facebook’s rules at the time, but the company did nothing to stop Mr. Kogan’s app from collecting the data.

“This is the frustrating bit, where Facebook clearly has never cared. I mean, it’s never enforced this agreement,” Mr. Kogan told “60 Minutes.”

“I had a terms of service that was up there for a year and a half that said I could transfer and sell the data,” he continued, adding: “Never heard a word.”

Until April 2015, Facebook allowed app developers to collect some private information from the profiles of users who downloaded apps, and from those of their friends. Facebook has said it allowed this kind of data collection to help developers improve the “in-app” experience for users.

Facebook even worked with Mr. Kogan. In November 2015, it brought him in as a consultant to explain the technique he had used for Cambridge Analytica, which focused on how the Facebook pages that users had “liked” could reveal aspects of their personalities.

“At the time, I thought we were doing everything that was correct,” Mr. Kogan told “60 Minutes.”

“If I had any inkling that what I was going to do was going to destroy my relationship with Facebook, I would never have done it,” he said.