PHL111: Valid Reasoning
Professor: Craig DeLancey
Office: Campus Center 212A
Office Hours: MWF 1:30 p.m. -- 3:00 p.m. and by appointment


This class is an introduction to formal or symbolic logic. This is the branch of philosophy that attempts to understand as clearly and precisely as possible the nature of good reasoning. Becoming skillful in logic is extremely useful, as good reasoning is essential to every endeavor you may undertake in life. We will study formal logic through developing some precise logical languages and then seeing how these languages can help us reason precisely.


We'll be using the following text, which will be available for free as an electronic text:
A Concise Introduction to Logic, Craig DeLancey
We will also be using clickers. These are required and are available in the bookstore. They cost less than a logic textbook would have; I recommend that you keep them, since you may find you can use them in future classes.

Assignments and exams

You will have four quizzes, weekly homework assignments, some credit given for class questions, and a final exam.

Logic is a discipline that requires practice, which is why we want to to frequent homeworks. They will be graded strictly, in order to make clear what you have done correctly and what not; but your overall homework grade will be curved. Also, note that I will typically give you questions about material we have not discussed in class yet. This is a way to get you to think about the material before the lecture, so that you are better aware of what the lecture is about, what you need to understand from the lecture, what you may be failing to understand, and so on.

You can work together, but you must write up your homeworks by yourself. This means that you will not get credit for identifiably identical homeworks.

There will also be short assignments asking questions about the readings. These must be completed on the Angel system.

If you have a disabling condition which may interfere with your ability to successfully complete this course, please contact the Disability Services Office.


SUNY mandates attendance for your classes. However, I do not grade you for attendance. There is, indirectly, some grading for attendance in the sense that I give points for answering some of the iClicker questions; but my motive there is only to recognize that the questions are important and to grade them so that you have some feedback on those questions. But this part of your grade is small.

Please note the following very important fact: I respect you and believe you should be allowed to manage your own time. But because I treat you with respect I demand that you act like you deserve that respect. That is: do not come to class to talk to the person next to you, to text message your friends back in the dorm, to surf Youtube, to read the newspaper. I consider this profoundly disrespectful, it distracts me a great deal, and it distracts the people around you. You can do these things somewhere else and I won't penalize you for doing so; so just stay in your dorm room, or go to the cafeteria, or anywhere else, if you want to do these things. Class time is for logic.

Of course, I understand that people like to talk to each other during class about class, asking their neighbor "what did DeLancey just say?" and so on. That's good -- in the best of all worlds we would all be doing that often during class. But manners require some taste and I'm sure you can show good taste in not overdoing that kind of talk to the point where I can't tell whether you're discussing logic or discussing lunch plans.

Similarly, don't come to class simply to leave after you hand in your homework, or come twenty minutes late, and so on. That's very distracting also.

I regret that I delete all the following emails and their equivalents unanswered: "I missed class today, can you tell me everything you said?" "I can't find the web site, can you type up the problems and email them to me?" "I know you don't accept the written homeworks by email, but can I email my homework just this once?" "I'm emailing my homework and will come to class sometime and give you the hardcopy then." "My roommate is in the hospital can you tell me whether I need to come to class today?" "Will we do anything important in class on September 29th?" And so on. You get the gist.

If you miss an exam and have an excused absence for the day you miss the exam, you may make it up, by special appointment with me, when you are able to come back to class. It is your responsibility to arrange any make-up exams as soon as you know you are going to miss the exam. Otherwise you may lose the opportunity to take the test, since I cannot give make-up exams after the class has gone over the answers.

Here is how you secure an excused absence: Only prior notification with credibly documented or easily verifiable reasons (e.g., medical visits to Mary Walker, documented participation in official sporting events, etc.) will result in excused absences. You must notify in writing, call, or email me prior to your absence from class. You must notify the Philosophy Dept. secretary, Pat Meleski, before you are going to be absent, via email at, or by phone at x2249. However, you must make sure she knows your name, the number of the course, the date, and your easily verifiable reason, along with a request to forward the information to me. It is better to give your information to me, except when you are unable to communicate with my phone or email for some reason.


The raw grade will be determined in the following way:
Homework assignments: 30%
Reading questions (on Angel): 10%
In class questions: 10%
Quizes: 30% (10% each)
Exam: 20%
In the past, I have used a curve to grade this class. I am going to attempt to grade the class using an objective scale this year. I will periodically post grade scale updates that will let you compute your grade.

Homeworks will typically be returned to you graded, and reviewed, in the class immediately after you hand it in. We will then review them together in that class. Homeworks will never be accepted after they have been reviewed.

You can always drop off a homework early by bringing it to my office. The secretary can put it in my mailbox; or, if no one is in, you can slide it under the door if it is clearly marked "FOR DELANCEY."

Please hold onto all of your assignments and exams. Sometime before the end of the semester I recommend that you ask me to review the grades that I have recorded to make sure that I have not made any mistakes. I'm only human and can make typos in recording grades! Grades will be put up on Angel, so you can and should check these.

Any forms of cheating will earn a zero grade, and will be reported to the Dean.

College Policy on Intellectual Integrity

Intellectual integrity on the part of all students is basic to individual growth and development through college course work. When academic dishonesty occurs, the teaching/learning climate is seriously undermined and student growth and development are impeded. For these reasons, any form of intellectual dishonesty is a serious concern and is therefore prohibited.

The full intellectual integrity policy can be found at


I will frequently update an online schedule of readings and yassignments. It is your responsibility to check the www pages for the class at least every other day!


Please leave your phones and pads at home. They are just a distraction to you and the people around you. I would ask you not bring a computer either (you can't easily take notes on it, because we use strange symbols) but some people claim to need them. Since I don't grade for attendance, this is not a tough policy: stay in your dorm room if you want to text message or check your email.

Office Hours

In addition to the listed office hours, I encourage you to make appointments. I am available quite a bit. Please try to come to office hours with specific questions in mind. You can of course come with a general request for help, but it is always helpful if you spend a little time thinking about how I can best help you out.

Learning goals

In this class, it is your responsibility to learn, and to be able to describe, explain, and apply:
  • what a valid and sound argument are;
  • all the elements of our language (terms, connectives, predicates, quantifiers, and maybe functions), their syntax (how they combine with other elements to make well formed formulas), and their semantics (in the case of connectives, this means their truth tables);
  • the inference rules we create to draw inferences from these elements;
  • how to translate simple English arguments into FOL;
  • the four proof methods and how to use them;
  • how to complete some original and novel formal proofs;
  • how to create your own valid arguments in English for novel claims;
  • Some examples of applications of logic to philosophical problems.