ERROR 12: MIXED CONSTRUCTIONS AND FAULTY PREDICATION
Definition
A mixed construction (also called a mixed sentence) occurs when a sentence begins with one grammatical structure and then shifts, without logic or agreement, to a different grammatical structure. The result is a sentence whose parts do not fit together grammatically or logically. Mixed constructions often arise when a writer begins a sentence without a clear plan of how to complete it, then changes course midway through and produces a grammatical mismatch.
Faulty predication is a specific type of mixed construction in which the subject and predicate (verb phrase) of a sentence are logically incompatible. This most commonly occurs with forms of the verb ‘to be’ when the subject cannot logically be equated with what follows it. Classic examples include sentences like ‘The reason is because…’ (reason ≠ because), ‘The purpose of education is to make students learn…’ (this can work), or structures like ‘When you study hard is the best way to succeed’ (when-clause ≠ a way).
Another common form of faulty predication involves defining a term using ‘is when’ or ‘is where’: ‘Irony is when something unexpected happens.’ This is considered incorrect in formal writing because ‘irony’ is a noun and ‘when something unexpected happens’ is an adverbial clause, not a noun clause that can define a noun. The correction uses a proper noun clause or a rephrasing.
Rules
RULE: Do not begin a sentence with one grammatical structure and complete it with a different, incompatible structure.
RULE: Avoid ‘is when’ and ‘is where’ as definitions. Instead, use a noun clause: ‘A drought is a prolonged period of abnormally low rainfall’ — not ‘A drought is when there is little rain.’
RULE: Avoid ‘The reason is because…’ Correct forms: ‘The reason is that…’ or simply ‘because…’ alone.
RULE: Make sure the subject and verb are logically compatible. Ask: ‘Can this subject logically do or be what the verb says?’
Examples
✗ The reason she left early was because she had a headache.
✓ The reason she left early was that she had a headache. [Or: She left early because she had a headache.]
✗ Democracy is when citizens vote for their leaders.
✓ Democracy is a system of government in which citizens elect their leaders.
✗ By working overtime gave her enough money for the vacation.
✓ Working overtime gave her enough money for the vacation. [Or: By working overtime, she earned enough money for the vacation.]
✗ A metaphor is where you compare two unlike things without using ‘like’ or ‘as.’
✓ A metaphor is a figure of speech that compares two unlike things without using ‘like’ or ‘as.’
✗ The reason I am writing is because of a concern about the new schedule.
✓ I am writing because of a concern about the new schedule.
✗ Just because you are older does not automatically give you more rights.
✓ Being older does not automatically give you more rights.
✗ Through careful planning helped the team meet its deadline.
✓ Careful planning helped the team meet its deadline.
✗ The report’s conclusion argues that the problem should be solved immediately.
✓ The report’s conclusion states that the problem must be solved immediately. [A conclusion doesn’t ‘argue’ — it states or proposes.]
✗ Procrastination is when you delay tasks that need to be completed.
✓ Procrastination is the habit of delaying tasks that need to be completed.
✗ Inflation is where prices rise and the purchasing power of money falls.
✓ Inflation is an economic condition in which prices rise and the purchasing power of money decreases.
Extended Dialogue
In this dialogue, graduate student Hannah is working with her thesis advisor, Professor Chang, on the opening chapter of her dissertation.
Prof. Chang: Hannah, your introduction has a number of sentence-level issues that we need to address before you go further. Some of your sentences break apart logically halfway through.
Hannah: I know some sentences felt off when I wrote them, but I wasn’t sure why.
Prof. Chang: Let’s look at this definition: ‘Cognitive dissonance is where a person holds contradictory beliefs.’
[Note: ‘Is where’ uses a locative (place) clause to define a psychological concept. A noun cannot be defined with ‘where’ unless it is an actual place. The correct form uses a noun clause or a rephrasing with ‘a state in which.’]
Hannah: I see — ‘where’ is for places. So I should write: ‘Cognitive dissonance is a psychological state in which a person holds contradictory beliefs’?
Prof. Chang: Exactly. When you define a noun, use another noun phrase or a clause introduced by ‘in which,’ ‘that,’ or ‘by which.’ Never ‘is when’ or ‘is where.’
Hannah: What about this sentence: ‘The reason many participants dropped out was because the study was too demanding’?
[Note: ‘The reason… was because’ is a classic faulty predication. ‘Because’ introduces an adverbial clause, but after a form of ‘to be,’ you need a noun clause introduced by ‘that.’]
Prof. Chang: That’s faulty predication. ‘The reason was because’ doesn’t work logically — ‘the reason’ needs to equal a noun, not a ‘because’ clause. Say: ‘The reason many participants dropped out was that the study was too demanding.’ Or even simpler: ‘Many participants dropped out because the study was too demanding.’
Hannah: And I also have: ‘By increasing sample size improved the validity of the findings.’
Prof. Chang: That one starts with a preposition phrase — ‘By increasing sample size’ — which sets up an expectation that a main clause will follow to complete the by-phrase. But instead, ‘improved’ becomes the main verb, which means the sentence has no subject.
[Note: ‘By increasing sample size’ is a prepositional phrase that acts as a modifier. It cannot be the subject. The sentence has no grammatical subject and is therefore a mixed construction.]
Hannah: So I need a subject: ‘Increasing the sample size improved the validity of the findings.’
Prof. Chang: Or: ‘By increasing the sample size, the researchers improved the validity of the findings.’ Either works. The key is that every sentence needs a clear subject performing the action of the main verb.
Hannah: These mixed constructions always happen when I try to write a sophisticated sentence and lose track of where I started.
Prof. Chang: That’s exactly it. The solution is simple: when you finish a sentence, go back to the beginning and check — does the end still fit the beginning? Does the subject make sense with the verb? Does the logical structure hold together all the way through?
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