MADISON, Wis. -- The author of a book about food that has sparked debate on the University of Wisconsin-Madison campus gave a lecture Thursday night in which he presented his ideas to supporters and critics in attendance.

UW-Madison selected Michael Pollan's best-selling book "In Defense of Food" for a campus-wide reading program, and the book's selection has set off a debate over the American diet and food production system in classrooms and far beyond campus borders.

An estimated 8,000 people attended Pollan's lecture at the Kohl Center on Thursday night, but Pollan's book and his lecture has been the subject of some criticism.

Some dairy farmers see the book as an attack on modern farming and are speaking out to defend themselves. Some university food scientists are criticizing some of Pollan's claims.

Wisconsin's mainstream farming group, the Wisconsin Farm Bureau Federation, said Pollan's conclusions about the farm industry are unscientific and biased, especially against larger farms and technologies.

Very early in the lecture, Pollan pointed out that Thursday's event was about the sharing of ideas.

"I'm well aware that not everyone in this audience is sympathetic to my work, or even my presence here, and I thank you too for coming to listen and participating in what's shaping up to be a really crucial conversation," Pollan said.

In his lecture, Pollan spoke about American farmers as the key to solving three crises in the country -- health care, climate change and the energy crisis.

Mary Ann Bellazzini and Nanci Cremer, self-proclaimed "foodies," attended Pollan's lecture to learn more about his views on farming.

"I just started a community supported agriculture farm, and Nanci is my volunteer, and so we're here to hear what he has to say about sustainable farming," Bellazzini said.

But others at Thursday's event said they see flaws in Pollan's ideas about the agriculture industry. Students like Macenzie Fochs wore specific T-shirts at the lecture to quietly demonstrate some alternate ideas.

"This is just meant to be very respectful. We're not going to sit her and say, 'He's bad; we don't like him,' that sort of thing," Fochs said.

Those wearing the T-shirts that read "In Defense of Farming: Eat food. Be healthy. Thank farmers" said they wanted to create a dialog about the issue and that it wasn't a focused effort at negativity towards Pollan.

UW-Madison officials said Pollan's thoughts about the American ideology about food is an opportunity for everyone to think about something so crucial to their lives.

"This is the Badger State; this is the state where we dig into things; we chew on ideas; we can even tear them up. We digest them also carefully. We don't spit them out without tasting them, and we don't swallow them whole," said UW-Madison Chancellor Biddy Martin.

On Friday afternoon, there will be a panel discussion about Pollan's and others' views on the agriculture industry and food from 3:30 to 5:30 p.m. at the Memorial Union Theater.