Mere Christianity is a written collection of spoken broadcasts given by CS Lewis during the Second World War. It aims to introduce “mere” (explicitly not defending any particular denomination) Christianity, with no prior background needed. It is apologetical, doctrinal, how-to, and ending with deep theology. An overall fantastic book, my current go-to recommendation for an excellent introduction to the what, why, and how of Christianity.
Definition of Christianity
The book proposes to defend the “core” of Christianity, while explicitly not making any denominational apologetics. In the preface, he insists on the need of having objective definitions for terms, because when a term ceases to be a description, it no longer carries meaning about the objects the term is applied to.
He chooses to define the term Christian as:
“We must therefore stick to the original, obvious meaning. The name Christians was first given at Antioch (Acts 11:26) to ‘the disciples’, to those who accepted the teaching of the apostles.”
As he proposes to not defend no particular denomination (although himself is an Anglican, and defends that people should affiliate themselves with a denomination), he needs to define what then is in and out. He is explicitly trying to remove moral connotations of the term, as Christian (more in his time, sadly not as much in ours) might be perceived as a moral judgement of one’s behavior, with Christian actions being seen as moral and non-Christian actions being seen as immoral.
I agree with his definition of Christian, but he is hiding a lot of historical-religious complexity under the rug. Jesus is such a time-dividing phenomenon that virtually every religious group after Him claims to be exactly what Lewis is using as a definition. Although he will defend what historians broadly call Nicene Christianity (the Christian denominations that accept the teachings of the Council of Nicea, encompasses Catholics, Protestants, Eastern Orthodox and others), Muslim, Mormons, Kardecists, and others will all tell you they are “Christians”, either explicitly or in the definition given by Lewis.
At the same time, pre-Protestant groups such as Catholicism and Eastern Orthodox believe that Christ founded one (holy, catholic, apostolic) Church, and that they are that Church. And in this sense, for these groups, they are not a denomination of Christianity, they are Christianity!
The Moral Law
Lewis starts the book on a discussion on the “Moral Law”, or “the Rule of Decent Behavior”. The Moral Law is the idea that human beings, differently from animals, have this natural interior notion of how they ought to behave. It is this interior sense that allow human beings to make moral judgements, to tell Right and Wrong apart from each other.
The Moral Law, differently from other “laws of nature”, such as gravity, can be broken, and in fact, humans break it all the time.
How do we know it exists
The Moral Law can be known internally through our own senses, e.g. guilt when we break it, or anger and disgust when someone else breaks it. It also can be known externally, through observing how similar moral codes and teachings are across time, culture, and religions, and how people behave.
There are variations in moral codes, but ultimately they are more similar than different. For example, some moral codes differ on who you should be unselfish towards, but no society promotes selfishness in an absolute sense, or the cowardness of a soldier.
Interpersonal conflict is also another area that the Moral Law can be externally observed. When facing the accusation of a breach of the Moral Law, people hardly will deny the law itself, but will try to either deny the fact altogether or point to some special excuse. For example, a politician accused of corruption never says “corruption is not wrong”, but usually will deny the fact, or at least explain away saying something like “it was for the good of the people”.
Objections
The Moral Law is not an instinct, like all other instincts that developed, and it is not a herd instinct, although we may have it as well. Lewis says:
“We all know what it feels like to be prompted by instinct—by mother love, or sexual instinct, or the instinct for food. It means that you feel a strong want or desire to act in a certain way.”
But feeling some desire is quite different from feeling you ought to behave in a certain way. He says:
“Supposing you hear a cry for help from a man in danger. You will probably feel two desires—one a desire to give help (due to your herd instinct), the other a desire to keep out of danger (due to the instinct for self-preservation). But you will find inside you, in addition to these two impulses, a third thing which tells you that you ought to follow the impulse to help, and suppress the impulse to run away.”
The thing that judges between these instincts and decides which should be encouraged cannot itself be either of them. Also, if the regulation of action in our mind was mere instinct, we would expect that the stronger instinct must win. But, in fact, we see the opposite: that in times when we are most conscious of the Moral Law, it tells us to behave in the side of the weakest impulse. Sometimes, we even convince ourselves or others to behave in a certain way by “waking up” an instinct through imagination, arousing our pity or courage, thus, clearly, the thing waking up the herd instinct (or another) cannot itself be the herd instinct. Brilliantly, Lewis gives the analogy of the instincts as piano keys, with the Moral Law the guide that tells us what keys we should play.
Some people will assert that the Moral Law is just a social convention, something we just learn from parents and teachers. We do, in fact, learn it from parents, teachers, friends, and books. But that, by itself, doesn’t make something a human invention or a social convention. We learn multiplication at school, and a kid growing up alone in a desert island would not know it, but that doesn’t mean that multiplication is something “made up” or that we could have made it differently if we wanted. There are some things we learn that are purely conventions (which side of the road we drive), but there are others such as mathematics which are real truths. The real question is to what class the Moral Law belongs.
The universality of moral teachings - i.e. the fact that differences of moral ideas are not very great between societies, religions and times - is a great reason to think that the Moral Law belongs in the same class as a real truth. But the greatest reason is the existence of moral reasoning: the fact that we all do believe that some moralities are better than others.
“Progress means not just changing, but changing for the better. If no set of moral ideas were truer or better than any other, there would be no sense in preferring civilised morality to savage morality, or Christian morality to Nazi morality.”
“We do believe that some of the people who tried to change the moral ideas of their own age were what we would call Reformers or Pioneers—people who understood morality better than their neighbours did.”
The fact that we can compare different moral ideas and say that ones are better than the others, truer than the others, or that humans ought to behave similarly to this one rather than that one, it is implied an objective standard: a Real Morality that some ideas get closer to than others.
If there is no Real Morality, or if morality is just a matter of personal preference, there can’t be “moral progress” or “moral decay”. There can’t be any affirmation that Christian morality is better or truer than Nazi morality. By this logic, you would have to affirm that the only difference of behavior from Hitler’s and Madre Theresa of Calcuta’s is just different hobbies.
Hume’s Guillotine
Lewis doesn’t talk about this, but I think it is noteworthy. Hume’s Guillotine (or “is-ought problem”) is a well-known philosophical issue that states one cannot logically derive an “ought” from an “is”. That is, it is not possible to conclude what should be done solely from statements about how things are. The move from factual claims to moral claims requires justification, or else it commits a logical fallacy.
Example: “People lie all the time (is), therefore lying is acceptable (ought).”. This is a fallacy. Just because something happens regularly doesn’t mean it is morally acceptable.
Thus, to do proper moral reasoning, and not create fallacious statements, an objective standard of morality (what ought to be done) is needed to ground and justify all further moral claims.