In a 1998 episode of the BBC political sitcom Yes, Prime Minster entitled ‘Power to the People’, the Cabinet Secretary Sir Humphrey Appleby and his predecessor Sir Arnold Robinson refer to what has become known as the ‘politician’s fallacy’. The fallacy in question runs as follows: 

‘We must do something.

‘This is something. 

‘Therefore, we must do this.’ 

The reason that this is a fallacy is because the ‘something’ in the first line is insufficiently precisely described. This means that any course of action could fulfil the qualification in the second line - ‘this is something’ - and therefore could be seen as that which must be done. 

How the argument should have run is: 

‘We must do something that will effectively address problem X. 

‘This will effectively address problem X. 

‘Therefore, we must do this.’ 

The politician’s fallacy which I have just described is an example of a wider category of logical error which is referred to in technical terms as ‘a fallacious categorical syllogism’.  

A categorical syllogism is a logical argument in three steps in which the conclusion logically follows from the previous two steps. An example of a valid categorical syllogism would be the following argument: 

A. A triangle is a plane shape with three straight sides and three angles. 

B. X is a plane shape with three straight sides and three angles. 

C. Therefore, X is a triangle. 

This is a valid argument because since A and B are true, C must therefore also be true. Another example of valid categorical syllogism would be: 

A. All philosophers are thinkers.

B. Some philosophers are teachers.

C. Therefore, some thinkers are teachers.

Here again, because A and B are true therefore C must also be true. 

A fallacious categorical syllogism, by contrast, occurs when what is stated in the first two steps does not lead to the conclusion drawn in the third step. Consider the following argument: 

A. All cats have four legs.

B. My dog has four legs.

C. Therefore, my dog is a cat.

This argument is invalid because although statement B may be true, statement C does not follow since it is not a sufficient definition of a cat to say that it has four legs. There are other creatures (including dogs) that also have four legs. Consequently, the fact that my dog has four legs does not make it a cat. 

A second example would be 

A. All students carry backpacks. 

B. My grandfather carries a backpack. 

C. Therefore, my grandfather is a student. 

This argument is invalid because it is not the fact of carrying a backpack that makes someone a student and so the fact that my grandfather carries a backpack does not make him one. 

The reason I have been thinking about these kinds of arguments recently is because of the development of the Living in Love and Faith process in the Church of England. What is becoming ever clearer as the process continues is that its only likely end point is the Church of England joining the ranks of those other churches around the world who have accepted same-sex marriage. 

The reason I say this is because of the dilemma facing those pushing for a liberal sexual agenda in the Church of England, which is that according to the Church’s immemorial teaching, marriage is exclusively between two people of the opposite sex and sex outside marriage constitutes the sin known as fornication. This creates a problem when it comes to blessing same-sex sexual relationships and ordaining those who are in such relationships. This is because from the standpoint of traditional Anglican theology (and of traditional Christian theology more generally) it is not permissible to either bless fornication or to ordain those who are habitual fornicators and those in same-sex sexual relationships must by definition be engaging in formication since their relation is non-marital. 

This leaves two routes open for those who support the acceptance of same-sex relationships. They can either go down the route of saying that sex outside marriage is not a sin, or they can say that the understanding of marriage can be expanded to include same-sex relationships. 

Although a number of bishops, including the former Archbishop of Canterbury, have made statements which reflect the first approach, I think it is likely that it is the second approach that will eventually be adopted because it is easier to present as indicating that there has been no fundamental change in Church of England doctrine. The Church of England stands where it has always stood, it will be said, holding that the proper place for sex is within marriage, but now it has an enlarged understanding of what marriage means in which two people who love one another can be married regardless of their sex. 

The problem with this approach, however, is that it depends on the validity of the following categorical syllogism: 

A. Marriage is a loving relationship between two people.  

B. A same-sex couple can form a loving relationship.

C. Therefore, a same sex couple can be married. 

There are two major difficulties with this syllogism. The first is that the definition of marriage in A makes it very hard to distinguish marriage from other forms of relationship. Thus, a father and a daughter, a brother and a sister, or two monks could be in a loving relationship. If marriage is defined simply in terms of being in a loving relationship, then it could be said that in all three examples the persons concerned were married to each other. 

Now, most people, if presented with these examples, would say they were ridiculous and that the people concerned cannot be said to be married to each other. The reason for this is because they hold that marriage involves something more than simply two people loving one another. If this were the case, for example, one would have to say that two people engaging in an affair are married to each other, which would be problematic since the very definition of an affair is a sexual relationship outside marriage. 

All this being the case the syllogism as it stands cannot work and therefore cannot be an argument for accepting same-sex marriage. 

The second difficulty is that the definition of marriage in A does not do justice to the understanding of the meaning of marriage that the Christian Church and Western society as a whole has held for thousands of years. 

This understanding is helpfully summarised by Sherif Girgis, Ryan Anderson and Robert George in their book What is Marriage? They note that the traditional view of marriage, what they call the ‘conjugal view’, sees marriage as a comprehensive union between two people made up of a number of interrelated elements which distinguish it from simple friendship. 

First, they write, marriage is traditionally consummated by coitus, the coming together of the husband’s penis and the wife’s vagina, and in this way: 

"… Marriage unites persons in their bodies as well as their minds. The bodily union of two people is much like the bodily union of organs in an individual. Just as one's organs form a unity by coordinating for the biological good of the whole (one’s survival), so the bodies of a man and woman form a unity by coordination (coitus) for a biological good (reproduction) of the union as a whole. In choosing such biological coordination, spouses unite bodily in a way that has generative significance, they do not merely touch or interlock. This generative kind of act physically embodies their specific marital commitment."

Secondly,  they declare: 

"… spouses unite bodily only by coitus, which is ordered towards the good of bringing new human lighting for world. New life, innocence, is one human good among others but in another sense, it transcends and includes other human goods. Having consented to sharing in the generative acts that unite them organically (as ‘one flesh’), spouses cooperate in other areas of life (intellectual, recreational, etc) in the broad domestic sharing uniquely apt for fostering the all round development of new human beings. Of course, they also cooperate in the tasks of parenting when children do come. Ordinary friendships - the union of hearts and minds embodied in conversations and in various joint pursuits - can have a more limited and variable scope."

Finally, they say:

"... In view of its comprehensiveness in these other senses, marriage inherently calls for a comprehensive commitment: permanence and exclusivity. Like the union of organs into one healthy whole organism, marriage is properly total and lasting for the life of the parts. (Indeed, comprehensive union can be achieved only by two people because no act can organically unite three  or more people bodily.) Again, marriage is uniquely apt for having and rearing children, an inherently open-ended task calling for unconditional commitment. But friendships as such require no promise of permanence ..."

Thus in their view, marriage involves bodily as well as mental responses and a "special link" to children and domestic life, as well as "permanent and exclusive commitment" - three elements that all "converge in, and go to constitute, the conjugal view". 

If this is what marriage is then there are insuperable problems with the syllogism supporting same-sex marriage. First, although a marriage is a loving relationship between two people, it is a specific kind of loving relationship. Secondly, this specific kind of loving relationship is one that by its very nature can only be between two people of the opposite sex. This is because, as Girgis, Anderson and George note, at the heart of marriage, traditionally understood, is the one flesh union brought about by coitus, an act involving a man and woman that has by nature generative potential.  

It is because this is the case that it is not arbitrary discrimination to say that two people of the same sex cannot be married. It is merely a statement of fact. They cannot be part of a comprehensive union with the act of coitus at its heart. This is why the comparison sometimes drawn between the rejection of same-sex marriage and the prohibition of inter-racial marriage is mistaken. The latter is arbitrary because two people of a different race can form a marital union, whereas the former reflects the fact that two people of the same sex cannot do so. 

What all this means for the Church of England’s Living in Love and Faith process is that the idea that the Church can redefine marriage to include relationships between two people of the same sex while claiming that this involves no change, and the Church can still stand where it has always stood, is an illusion. As we have seen, the argument that two people of the same sex who love one another can be married is incompatible with the traditional understanding of what marriage is and involves a definition of marriage that makes marriage indistinguishable from forms of relationship that would be universally recognised not to be marriage at all.  

As if this were not enough, the Church of England has always held that the traditional conjugal view of marriage is one that was instituted by God himself at creation. What would therefore have to be established is that this view was mistaken and that we now know that God supports the redefined view of marriage. No one has yet managed to make a plausible case for either proposition. 

Finally, all the available social science evidence we have tells us that societies flourish best when children are brought up by their biological parents in a relationship in which their parents are permanently and exclusively committed to each other and committed to the flourishing of their children. This form of a relationship is becoming increasingly rare in British society and so why would the Church of England want to further undermine it by supporting a new understanding of marriage which has no necessary connection to the birth and nurturing of children?