reason ... is because

According to Jonathan Swift, "The reason why so few marriages are happy is because young ladies spend their time in making nets, not in making cages." *

Regarding other matters of the heart, William Harvey observed that "the reason why the pulmonary artery has so large an orifice is because it transports much more blood than is requisite for the nutrition of the lungs." *

Faulty syntax---always an unpleasant thing to behold---is especially disturbing when it comes from an otherwise respectable source. The inevitable effect of such lapses is to fuel the cause of linguistic anarchy, compounding the burden on those of us who would preserve order. With regard to the ubiquitous locution the reason ... is because, our efforts appear to have fallen short.

A natural reaction to this barbarism is simply to condemn it as a redundancy. Follett, for example, notes that "because = for the reason that. Therefore, 'the reason is because' means 'the reason is for the reason that.'" Similar censures have been issued by numerous commentators, including Treble and Vallins, Fowler, Bernstein, Lovinger, Bremner, and Garner. Even Burchfield yields to the conservative view on this issue. Responding on behalf of the descriptivists, Gilman protests that the definition of because has been manipulated in such a way as to guarantee that the offending phrase is redundant or nonsensical. But in any case, the charge of redundancy by itself is a weak objection, as a considerable measure of redundancy is inherent in any natural language. What distinguishes this construction from the time ... is when or the place ... is where? One could argue that since the meaning of where is at the place at which, the following must be at least equally objectionable:

But whether on the scaffold high
   Or in the battle's van,
The fittest place where man can die
   Is where he dies for man. *
But somehow, this verse is relatively inoffensive. Since there is as much semantic overlap between place and where as between reason and because, it is clear that our objection to the reason ... is because will require a firmer footing.

The real issue here is one of grammar rather than style or enonomy of expression. A subordinate clause introduced by the conjunction because is always adverbial, never substantival, and cannot, therefore, be linked as a predicate nominative to the subject reason. Although Gilman would dismiss this precept as an arbitrary invention of the twentieth century, "erected ad hoc to rationalize dislike of the reason is because", it has been consistently supported by all who have investigated the etymological classification of conjunctions, including such noted nineteenth century grammarians as W.C. Fowler (1851) and Eduard Maetzner (1874).

The rationale for this classification, however, has never been explained. What requirement of a substantive is unsatisfied by a clause introduced by because? According to the time-honored definition, which may be traced back to John Ash (1785), "A Noun, or Substantive, is the name of any Person, Place, or Thing." Catchy, but of little utility, as the notion of thing is no less obscure than that of substantive. The deeper general meaning of the word, as derived from the Latin substantivus, is that which stands under, as a foundation, and therefore has an independent existence or status. Accordingly, a more rigorous definition of the grammatical term was formulated even earlier than Ash by Michael Maittaire (1712):

The Subftantive fignifies fomething, which can ftand by itfelf and be underftood in the fentence without the help of another noun; as the air, the fea.
In the context of Maittaire's criterion, it is clear that a conjunction such as because, which denotes a certain relation between its conjuncts (namely causality), cannot properly serve as the prefix of a noun clause. For example, in the statement The Knicks lost the series because DeBusschere was injured, the subordinate clause because DeBusschere was injured does not signify something with independent status, but can only be understood in relation to the consequent of the causal relation, The Knicks lost the series. In other words, to be a cause or a reason is not an intrinsic attribute. Thus, in attempting to reformulate the sentence as The reason the Knicks lost the series is because DeBusschere was injured, we are miscasting the same subordinate clause as a substantive. The error is corrected by replacing because with that, a conjunction that merely signals a proposition (rather than a relation between two propositions), which may legitimately serve as a substantive: The reason the Knicks lost the series is that DeBusschere was injured.

Some readers will find this explanation unpersuasive. In general, there is little to be done for those who are impervious to logic and committed to the view that usage by esteemed authors constitutes correctness. In this instance, however, we find a strange variation on this theme, arranged by Evans et al., which cannot be ignored:

Because may certainly introduce a noun clause that is joined to it, this, or that by some form of the verb to be .... This has been standard English for centuries and the very grammarians who condemn the use of because in a noun clause do not hesitate to write this is because.
The underlying assumption that any phrase preceded by it is or this is must be a substantive is puzzling. In common English, a form of to be may be followed either by a substantival or adjectival phrase linked to the subject, or by an adverbial phrase attached to the verb. (See feel badly for further discussion of adverbial modification of linking verbs.) In the sentence It is here, which is irreproachable English, could the word here (unequivocally classified as an adverb by all dictionaries in my collection) possibly be mistaken for a noun?

When a noun or substantive is linked to the subject of a sentence by is, the resulting meaning is the identification of the referents of the two phrases. This is clearly the intention, for example, of the line quoted earlier from Swift: the subordinate clause, because young women spend their time in making nets..., is meant to identify the reason why..., and is thus linked to the subject as a predicate nominative, i.e., is misused as a substantive. On the other hand, consider the following example, provided by Gilman:

Perhaps this staunchness was because Knight ever treated him as a mere disciple.
--Thomas Hardy, A Pair of Blue Eyes, 1873
The critical difference between this construction and Swift's is that the subject of this sentence is the consequent of a causal relation rather than the antecendent. What conceivable meaning could be assigned to the clause because Knight ever treated him as a mere disciple that would allow it to be linked as a predicate nominative to the subject, staunchness? On the contrary, rather than defining the subject, the subordinate clause serves here as an adverb, describing how the staunchness came to be, i.e., modifying the verb is.

In support of Evans's position, Gilman observes that "Fowler, who condemned reason is because, used it is because himself without thinking." Indeed, we find the following in The King's English:

Which suggests the further observation that the with a comparative is almost always wrong when a than-clause is appended. This is because in the full double clause there is necessarily not a fixed standard of comparison, but a sliding scale.
But note that the subject of the sentence under scrutiny, the pronoun this, refers to the observation of the preceding sentence, which again is the consequent of the causal relation. Thus, we have another legitimate adverbial use of a because clause. We are not surprised to find that even an unthinking Fowler is more astute than his most deliberate detractor.