I've attended the 24 Harvard University lectures that the book is based on; that's why I'm going to consider that I read the book.
The topic, the way it was structured, presented and executed was one of the best I've ever experienced. It is arguably the best online course on philosophy you could attend.
In a nutshell, Michael Sandel discusses: What's the right thing for humans to do, whereby he explains theories around Justice, morality and human good. In order to do so, he constantly starts with a controversial (real or theoretical) case study to juxtapose different theories of justice and morality.
For example Michael Sandel starts with the classic example of a train headed towards 5 people on the track. The breaks don't work. If the train continues it will kill the 5 people. Then he introduces the option of pulling a leaver to switch to another track whereby only 1 person is standing. The question is: What do you do?
Through such examples he explains different schools around morality and justice.
1) The Utilitarian view: This school advocates maximizing "pleasure" to the largest "number" of people. By doing so, the individual and the society are acting morally and justly. As such, the moral and just decision for the utilitarians is: to chose to kill the one person instead of five, as this maximizes the "pleasure" as much as possible. This maximization is, in itself, the prime/only moral justification.
The challenge happens when Sandel introduces a twist to the example: "What if there was no other track, and you were a on a bridge watching the train heading towards the 5 people. Now, imagine there was a very large person standing next to you. If that large person falls on the tracks and hits the train, the train will stop and as a result, not kill the 5 people. If you had the opportunity would you push that person of the bridge? From a utilitarian perspective, how can you argue against doing this? given that the outcome is the same as chosing the 2nd track with one person on it. As both options maximize the good.
Obviously, the utilitarian school isn't that shallow, but this gives you glimpse of the philosophical implication of rationalizing morality through maximizing pleasure or good.
Another challenge is around the inherent moral value of a given deed; if maximizing good/pleasure is the rationale, an individual action might be moral in one scenario and immoral in another according to the collective pleasure.
2) The libertarian view: This school advocates maximizing individual freedom (freedom to do what a person pleases with their lives, time and possessions (e.g. money, property). Issues such as: Consent, equality, minimizing state interference/taxation, and social contracts are major themes here. So any action that results in maximizing individual freedoms (without resulting in material harm on other individuals or liberties) is moral. As you can imagine, the libertarian school of thought would advocate against switching the tracks as that results in involving the additional person to the equation without their consent.
The challenge with this line of thinking is: What if two people consent to horrific actions to be done on one another e.g.
- ( in Germany someone (X) put an add that they want someone (Y) to to apply to be killed and eaten by him. Eventually, another person (Y) volunteered and they both (X and Y) executed the act.) What do you do then?
- ( in some native american cultures, taking drugs is part of the religious experience) should the government allow them to do so? If yes, what If I come up with a religion and register it and say that consuming cocaine is part of my religion? what then?
- ( in some parts of Canada indulging in sexual acts with animals is legal) Why? because there is no infringement on individual freedoms
The challenge now becomes, what do we do if a mother and her son want to have sexual intercourse? two siblings? or a person wants to ride a motor bike without a helmet? shouldn't taxation be banned (as it infringes on individual's ownership)?
As a result, all judgement of acts are skewed towards the one measure (freedom).
3) The virtue or Teleology school: whereby it focuses on ensuring achieving virtues or purpose. This has been originally argued by Aristotle. The idea here is that one needs to understand the underlying meaning of something (e.g. life, economy, marriage, money) and its purpose in order to say what is just and moral.
The example here is about a golfer who has a bad leg and wanted the PGA to provide him with a cart. The PGA refused, and the case went up to the supreme court. The main debate was: is walking an essential part of golf? if it was, then providing a cart is unfair. Also if someone suggested to give everyone a cart then it changes the nature of the game itself.
The challenge in this school is a very deep and philosophical one. Who decides on virtue and purpose? one of the earlier arguments was that each group/society sets them. The challenge is: what if the group or society agrees on something like slavery or segregation of people of color, or banning Hijab?
This is where Michael Sandel argues that speaking of justice requires embarking on finding a framework to answer/define the 'Telos' of life. Is it God and religion? can pure reasoning get us there?
Overall a very thought provoking book and lectures that I recommend you start asap