What Does "that's why" Mean?
- Grammatical function: That's why indicates a consequence or result of something previously stated or implied. It establishes a cause-and-effect relationship, where the preceding context is the cause, and the clause introduced by that's why is the effect.
- Typical sentence position: Initial
- Register: Neutral
How to Use It
- Syntactic patterns: That's why is typically followed by a clause (subject + verb + optional objects/complements). It usually comes after a statement or situation that explains the reason or cause. It can be preceded by a full sentence, a clause, or an implied context.
- Punctuation rules: Usually, a comma is not needed before that's why when it begins a new sentence. However, when it appears mid-sentence, it is often set off by a comma if the preceding clause is relatively independent.
- Grammatical flexibility: That's why can start a sentence and can sometimes be moved within a sentence for emphasis, though this is less common and can sound awkward. It's generally not negated directly, but the clause following it can be.
- What sounds unnatural or incorrect: Using that's why to introduce a cause rather than a consequence is incorrect. For example, saying "That's why I was late because the bus was delayed" is incorrect. It should be "The bus was delayed; that's why I was late."
Real-World Examples
These examples are sourced from that's why on Ludwig.guru.
"That's why education programs are in English." — Procedia - Social and Behavioral Sciences
"That's why we digitize." — Princeton University
"That's why we're here." — Massachusetts Institute of Technology
"That's why elections matter." — The New York Times
"That's why it's disappointing"." — The New York Times
Examples sourced from https://ludwig.guru/s/that's+why
Similar Phrases and Alternatives
| Phrase |
Context |
| therefore |
More formal and emphasizes a logical deduction; suitable for writing. |
| consequently |
Similar to therefore, but often implies a more direct and immediate result. |
| as a result |
More formal and emphasizes the direct link between cause and effect. |
| for that reason |
Slightly more formal; can be used to introduce a more elaborate explanation. |
| that is why |
A more emphatic and slightly more formal version of that's why. |
| hence |
Highly formal and somewhat archaic; best suited for academic or legal contexts. |
| thus |
Formal alternative, often used in written arguments or explanations. |
Common Mistakes
- Using that's why to introduce the cause instead of the effect. The correct usage presents the cause first, then that's why followed by the effect.
- Omitting necessary context. That's why requires the listener or reader to understand the preceding cause, either explicitly stated or implicitly understood.
- Learners sometimes confuse "that's why" with "because of that," using them interchangeably even though "because of that" often requires a more formal context or a noun phrase following it.
Quick-Reference Summary
| Expression |
Function |
Register |
Typical Position |
| That's why |
Indicates a consequence or result |
Neutral |
Sentence-initial |
FAQs
Where can "that's why" appear in a sentence?
That's why typically appears at the beginning of a sentence or clause. While it can technically appear mid-sentence, placing it at the beginning is the most common and natural way to use it to clearly signal the consequence of a previous statement.
How is "that's why" different from "because of that"?
Both phrases indicate a cause-and-effect relationship, but that's why is more conversational and commonly used to introduce the consequence. "Because of that" is generally more formal and often introduces the reason or cause, requiring a noun phrase after it.
How can I correct the mistake of using "that's why" when "because of that" is more appropriate?
If you find yourself incorrectly using that's why where the context calls for a more formal expression or a noun phrase, rephrase the sentence using "because of that" followed by the specific reason or cause. For example, instead of "That's why the event was cancelled," you could say "Because of the weather, the event was cancelled."