Leonard Peikoff Grammar Course Lecture 6 Notes

Peikoff Grammar Course Lecture 6 Notes

More work on Leonard Peikoff’s Grammar Course.

I marked points I thought were particularly interesting with a ❗️.

Big Picture

Early Greek had no punctuation or spaces between words. Punctuation had to be invented, was an achievement.

Purpose of punctuation: we can only hold so many units in mind at a single time. Crow epistemology. Therefore we have to reduce the number of units into fewer units. This came up earlier with subordination. Punctuation tells us when to add up words into a single unit.

We are always breaking things up and putting them together. E.g. looking at a face, you look at each element (eyes, nose) and then put things together. Punctuation is analysis of sentences. Gives you guide for how to break up sentence and grasp meaning.


Woman without her man would be lost.

Two different meanings depending on punctuation:

Woman, without her, man would be lost.

Meaning: Man would be lost without woman.

Woman, without her man, would be lost.

Meaning: Woman would be lost without her man.

Too Much Punctuation

You can break stuff up into so many units using too much punctuation that you defeat the purpose of using punctuation.


The jar, however, being light, and, therefore, not round, was costly.

Peikoff personally doesn’t include punctuation unless it’s mandatory.


Pause Test

Some people think you don’t need to know punctuation rules because you can just put a comma where you’d put a pause. Problems with this:
1. might make mistakes on where to pause
2. pause test used to be applicable but is no longer true. different punctuations were correlated with different lengths of pauses, with shorter to longer pauses for comma, semicolon, colon, and period respectively. Things changed. Use of punctuation is now based on nature of division between one unit and the next, not pause length. Comma indicates units are close to each other, semicolon is in the middle, and period indicates separation.

Uses of Commas

Separating Main Clauses

I went to the bank, and the teller told me I was bankrupt.

Comma is mandatory when you are joining two independent clauses.

Jack came into the room, for Harry did not want to go.

Same as before – mandatory.

Proper use of commas in these cases prevents the reader from having to double back and reread to figure out what is going on.

This usage applies only to sentences separated by coordinating conjunctions.

Exception: Clauses Short & Closely Connected

Two very short clauses don’t strain the crow epistemology.


He ate and he drank until he fainted.

Peikoff: 3 clauses, 2 main clauses, but all clauses are so short that no commas are needed.

Separating Parenthetical Elements

Long Introductory Phrase or Clause.

Comma mandatory in such cases. Example:

Given the huge number of Americans who do not belong to any union, we have a good chance of combatting the influence of the AFL-CIO.

Comma indicates boundary between main part of sentence and introduction.

No Comma Needed After Short Intros


In the afternoon he takes a walk.

I’d typically put a comma here but Peikoff says it is not needed.

If I come I can stay until noon.

Element In Middle of Main Clause

His mouth, though filled with peanuts, still issued commands.

Commas indicate that something has been inserted into the main structure of the grammar (which is “mouth…issued commands”).

He will, without any hesitation, betray his country.

Element inserted inside the verb phrase “will … betray”.

No Need To Set Off Parenthetical Elements at The End

You already know the main clause by the time you get to a parenthetical element at the end of the sentence, so there is no need to indicate the boundary.

I saw a burglar as I entered my apartment last Sunday.

No comma needed here.

Elements That Modify Sentences or Clauses as a Whole

Elements that modify whole sentences or clauses are not part of the grammar and thus need to be set off with commas.

We sang, that is, until it was dark.

“that is” is a sentence modifier. It modifies whole thing, like “therefore” or “however”, and needs commas to indicate that it is standing outside the core grammar of the sentence.

Exception: Brief Element

Your contribution will of course be appreciated.

Commas option around “of course.”

Exception: Things Like “I thought” and “he said”

No comma needed for these short expressions of mental state.

The book which I thought he was reading…

“I thought” does not need commas.

Exception: Negative Adverb

Don’t set off negative adverb statements with commas e.g.:

He will under no circumstances go home.

Peikoff says if you put commas around “under no circumstances” then the reader takes in the “he will … go home” and then the “under no circumstances”, so you kind of undercut the negating element.

Alternatives to Commas for Parenthetical Remarks

Peikoff says greatest emphasis to side remark is given by dashes, least by parentheses, and middle amount of emphasis is commas.

Three variations on a sentence. This one just uses commas:

U.S. foreign policy, or lack of it, is the cause of Russia’s success.

Peikoff says this phrasing is kinda neutral, saying that either U.S. foreign policy, or lack of it, take your pick, is the cause of Russia’s success.

I actually have some trouble reading all three variations of this sentence as anything other than somewhat sarcastic comments about U.S. foreign policy. I’m bringing in a lot of context to how I read this sentence. I don’t think it’s a great sentence for isolating the grammar issues that Peikoff wants to talk about.


Dashes give greatest emphasis to side remark compared to alternatives. A dash = a break or rupture in the thought.

U.S. foreign policy—or lack of it—is the cause of Russia’s success.

Peikoff says this is like saying “actually this is so important I have to correct myself. Actually we don’t have a foreign policy.”


Least emphasis.

U.S. foreign policy (or lack of it) is the cause of Russia’s success.

❗️Setting Off Non-Restrictive Modifiers

Non-restrictive, inessential to sentence, need to use commas:

Grand pianos, which are uncommon, are necessary to modern orchestras.

Without commas you could read this as “The uncommon type of grand piano is necessary to modern orchestras.”

Restrictive, crucial to sentence, no commas:

Grand pianos which are out of tune are a performer’s nightmare.

❗️Peikoff says that not putting commas around restrictive clauses, and putting them around non-restrictive clauses, is actually just a development of the rule that you should put commas around parenthetical remarks. When something isn’t parenthetical – when it’s essential to the meaning of the sentence, then you don’t put commas around it. I thought that was a good point 🙂

Example of incorrect use:

A grand piano, that is expensive, is a needless luxury.

Cannot use relative pronoun “that” after a comma. Why? It’s ambiguous between relative and demonstrative pronoun – in this example it encourages a reading along the lines of “A grand piano, that (meaning such a thing as a grand piano) is expensive!” for the first part of the sentence. (Not sure I agree with this reasoning but I agree with the rule.)

If you’re going to separate a phrase by commas, must use “which” or “who”, not “that”.

Testing Relative vs. Non Relative

Omit Clause

Grand pianos, [which are uncommon], are necessary to modern orchestras.

Makes sense without the stuff in brackets.

Grand pianos [which are out of tune] are a performer’s nightmare.

Peikoff says this makes less sense. I think the better thing to focus on is that there is a major change in meaning.

❗️Drop Commas and Substitute “And” + Personal Pronoun

Don’t think I have seen this technique before!

Grand pianos [and they are uncommon] are necessary to modern orchestras.

I can follow that, though the part in bracket strikes me as a bit of a side remark.

Grand pianos [and they are out of tune] are a performer’s nightmare.

Yeah this doesn’t make a lot of sense.

Examples with Relative Clauses

People who live in glass houses should not throw stones.

I think this does not get commas. The intent isn’t to say that people should not throw stones and then have an aside about the people happening to live in glass houses.

Peikoff: Agrees.

Your new car which is parked in the garage is badly dented.

I think this does get commas around “which is parked in the garage”. The location of the car is incidental to the story that the sentence is telling.

Peikoff points out that you could read this as it is written to be specifying which car for someone with multiple new cars. I can see that, though I think that’s a somewhat rare context.

She spent her time feeding ice cream to the children who were good.

This could be read either way.

As written (as a restrictive clause) it would mean that the ice cream was being fed specifically to the good children.

With a comma before “who were good”, it would mean that the ice cream was being fed to all the children, and by the way the children were good.

Peikoff: agrees.

The best idea that Jack got was to go dancing.

No commas cuz of “that”. Restrictive. Jack got various ideas, best one was to go dancing.

Peikoff: says you could put commas around “that Jack got” and it would be a legitimate sentence which would mean something like: “The best idea, which came from Jack, was to go dancing.” This interpretation seems weird to me, and using a comma before the relative pronoun “that” seems to contradict Peikoff’s earlier statement that that should never be done. 🤔

Oh ok, Peikoff clarifies in response to a student question, and he says that you’d have to change the “that”. So he means that it would be a legitimate sentence with some rewriting…
BTW tangential comment, the students on these tapes are not passive, and often ask the very questions I am wondering about. That’s nice.

The dog who loves his master is an ideal pet.

Restrictive reading (no commas around “who loves his master”): Master-loving dogs are ideal pets.

I’d read the restrictive interpretation as a general statement – like, talking about dogs in general, not a particular dog.

Nonrestrictive reading, with commas around “who loves his master”:

The dog loves his master and by the way he’s an ideal pet.

I’d probably read the non-restrictive version as being about a particular dog.

Peikoff: reads the non-restrictive version differently, thinks it would mean that all dogs, in general, love their masters and are therefore ideal pets.

Adaptation of Floyd Ferris Atlas Shrugged sentence:

A study of space leads us to contradictions which are impossible, according to the human mind, but which exist nevertheless.

Should there be a comma after contradiction or not?

If you read “which are impossible” as restrictive as relates to contradictions (so no comma), then you have to read the clause “which are impossible” as conveying essential information. In this case, that means that you’d be specifying that you are talking about the impossible type of contradiction (as opposed to the other types?)

On the other hand, if you put a comma after “contradictions”, so that it’s non-restrictive, then the “which are impossible” just becomes a fact about the general subject of contradictions that has been already introduced.

Peikoff agrees.

🤔Tangential comment: I think these restrictive/non-restrictive exercises are good cuz they encourage thinking about sentences in a very literal way, even if the literal way leads to some interpretations that are bizarre in a typical context. The exercises somewhat turn off the “interpret everything according to common sense” program in the brain that can get in the way of doing very a literal reading.

Examples Other Than Relative Clauses

At the end of August, when fall was approaching, I decided to quit my job.

Non-restrictive interpretation: If you keep the commas around “when fall was approaching”, then “when fall was approaching” sounds like it’s somewhat independently giving information about when the decision to quit happened.

Restrictive interpretation: with no commas, it sounds like you’re qualifying the part of August, as if to specify the part of the end of August when fall was approaching (as opposed to the parts of the end of August when fall is distant?). This reading makes less sense to me.

Peikoff: basically agrees.
After listening to Peikoff and thinking more, I don’t think the “when fall was approaching” is “somewhat independently” giving information like I said earlier. I think it’s pretty attached to “At the end of August.”

Beaten, I fell to my knees.

Has to be non-restrictive, and would therefore be read (as written with the comma) with a meaning like “As I was beaten, I fell to my knees.”

If you read it as non-restrictive, it becomes “Beaten I fell to my knees”, so you’re talking about the Beaten you as opposed to the non beaten you, maybe cuz there was a mixup in the Star Trek transporter and you and your double followed different life paths afterwards.

Peikoff agrees.


Peikoff notes that most appositives can be expanded into non-restrictive clauses. Compare:

Jesse, the caretaker, is a good fellow.

This is in appositive form.

Jesse, who is the caretaker, is a good fellow.

This is a non-restrictive clause.

Sometimes appositives are restrictive:

The poet Sandberg has written a biography.

“Sandberg” is an appositive providing essential detail about “poet.”

She loves my favorite composer, Rachmaninoff.

Has to be non-restrictive (as it is written), in which case, “Rachmaninoff” is merely renaming “composer.”

If you delete the comma and turn it into something restrictive, then you’re discussing the type of Rachmaninoff as being the composer Rachmaninoff, as opposed to the chef type of Rachmaninoff or Uber driver type of Rachmaninoff.

The idea that socialism is good is ridiculous.

“that socialism is good” is an appositive renaming “idea”. It is also essential to the meaning of the sentence and is therefore restrictive.

Many evil people, such as Hitler and Stalin, were once in power.

This is correctly punctuated as non-restrictive. The core grammar is “Many evil people … were once in power” and the non-restrictive clause “such as Hitler and Stalin” is merely giving some illustrations.

People such as Hitler and Stalin were evil.

This is correctly punctuated as restrictive. “such as Hitler and Stalin” is essential to the meaning of the sentence, which, without that clause, would merely read “People were evil.”

❗️Serial Commas

He likes to speak French, German and Italian.

Is comma before “and” required? Authorities are divided. Peikoff does not use the Oxford comma.

❗️ Peikoff mentions this argument: starting out from “French and German and Italian”, the comma takes the place of the first “and” between French and German, so if you have a conjunction separating the second and third items (German and Italian in this example) then there is no need to have the comma.

Case where serial comma is obligatory:

Modern women do not wish to remain home, cook, and nurse children.

With no comma, it sounds like maybe modern women don’t want to cook children.

(This reminds me of an example sentence I heard elsewhere of someone receiving an award and saying “I’d like to thank my parents, Ayn Rand and God.” 🙂)

Coordinate Commas

Similar issue to serial commas. If adjectives are “coordinate” – each separately modifying noun – need commas.

A clean, quiet room…

Both are adjectives are modifying “room”, so commas are needed.

Test for coordination: can you change the order? If so, then they are coordinate.
Another test: can you replace comma with an “and”?

A tall oak tree…

You can’t say “oak tall tree”, cuz “oak tree” is functioning as a single unit, so you don’t use a comma.

A beautiful young lady…

“young lady” is a single unit, so no comma after beautiful

A beautiful, new car…

“car” stands independently and is modified by both “beautiful” and “new” so we use a comma here.

Preventing Misreading

Before eating the girls peeled the vegetables.

Need a comma after “eating” or else it sounds like someone is eating the girls.

After all the trouble we took is worth it.

Need a comma after “After all” for this intro/parenthetical remark, or else you just keep on reading and then have to double back to figure out what the heck is going on.


Many, if not most of the children were tired.

We want a comma after “most”. Kind of a special case of parenthetical.



He asked for the answer; but I did not know it.

What does the semi-colon do here? Gives a longer pause and greater emphasis. (This seems more in line which pause theory of punctuation, which Peikoff was criticizing earlier). This one strikes me as kind of wrong. At 32:18 in the audio someone asks if the semicolon makes the conjunction unnecessary and Peikoff says no, but seems to indicate that expressing the “but” is optional but permitted. I think the “but” should be dropped if you are going to use a semicolon, and if you really feel like you need a “but”, you should drop the semicolon. This Grammarly guide says to delete conjunctions when you use a semicolon.

Side note: I noticed in listening to the YouTube video that ARI seems to have run the lecture through some heavy, heavy noise removal, because the audio has the characteristically “tinny” sound of being heavily processed through such an algorithm, and this actually makes the audio quality of the YouTube version worse than the audio files.

Joining Two Clauses Without a Conjunction

If you want to express two main clauses as one thing without commas, you need a semi-colon:

It is nearly half past five; we cannot reach town before dark.

You could put a period in but would lose the idea of taking things in as one thought:

It is nearly half past five. We cannot reach town before dark.

You could also use a conjunction, of course:

It is nearly half past five, and we cannot reach town before dark.

The above variations are all okay grammatically, and which you use depends on what you want to do.

This is always incorrect:

It is nearly half past five, we cannot reach town before dark.

Peikoff says there is no guide to the grammar here – the comma does not indicate whether we are dealing with a parenthetical remark, clause, etc.

Before Adverbial Conjunctions

He asked if we wanted to leave; therefore, we took the elevator.

Peikoff: why couldn’t we use a comma “to leave”? Because an adverb can look back as well as forward and so you need a harder stop to indicate the intended grouping.

Comparing Comma & Semi-colon

For punctuating main clauses in relation to each other:

Separated by coordinating conjunction – use a comma.
No conjunction – use a semicolon.
Adverbial conjunction – use a semicolon.

Semicolons for Items in a Series

Can be fine if your series is punctuated internally by commas.

Invalid Uses of Punctuation

Using Comma to Separate Object and Verb

The book says, that the ship sank without a trace.


Indirect-Direct Discourse Switch

My friend asked whether I knew the truth, and, if so, would it be important for him to learn it also?

You want both of these to be indirect, with no question mark. The sentence starts off by relating the content of the question but then shifts into actually asking a question. So what you want is something like:

My friend asked whether I knew the truth, and, if so, whether it would it be important for him to learn it also.

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