PHL111: Valid Reasoning
Professor: Craig DeLancey
Office: Campus Center 212A
Office Hours: MF 2:00 - 4:30 and by appointment

What this course is for

Logic teaches many things, but perhaps the most important is how to reason. Logic will teach you thinking skills that work for any discipline, that can help you achieve any goal. Logic is the most general and powerful method of reasoning we have. The more logic you know, the more powerful your thinking abilities will be.

Logic will also help you avoid deception. Speaking in Canandaigua, New York, on August 3, 1857, the escaped slave and abolitionist leader Frederick Douglas observed that:
Power concedes nothing without a demand. It never did and it never will. Find out just what any people will quietly submit to and you have found out the exact measure of injustice and wrong which will be imposed upon them, and these will continue till they are resisted with either words or blows, or with both. The limits of tyrants are prescribed by the endurance of those whom they oppress.
We can add to Frederick Douglas's words that: find out just how much a person can be deceived, and that is just how far she will be deceived. What logic teaches you is how to demand and recognize good reasoning, and so how to avoid deceit. You are only as free as your powers of reasoning enable. This is the dream of the Enlightenment: to empower each person to think for herself.

Your commitment: What you must do to achieve these goals

Logic is a discipline that requires practice, which is why we want to have frequent opportunities to practice. To succeed, you will read the textbook, test your understanding through answering questions, but then-- most importantly--you will practice logic by doing all of the assigned practices.

We'll be using the following text, which will be available for free as an electronic text:
A Concise Introduction to Logic, Craig DeLancey
Don't worry about grades, except to use them as an indicator of what you need to keep working on. But, to generate a final grade, the work will be weighed in the following way:
Practice assignments: 40%
Quizes: 30% (15% each)
Exam: 30%
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 could be, indirectly, some grading for attendance in the sense that I might 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 will be small if existent.

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. You can hand your work in at the Philosophy Department Office, if you only want to do that.

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, Lori Reitmeier, 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.

A note about late homework: I go over homeworks in the class after you hand them in. That means I can't accept a homework after that review, since it would be impossible to assess how you would have done on your own at that point. If you give me a homework late but before we review it in class, I will accept it, but it goes into my LATE pile, and I get to it someday--but it may take me a long while, and sometimes I won't grade late homeworks until finals week. So, it's much less useful for you because you might not receive timely feedback that way.

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 somewhere packed away. They are just a distraction to you and the people around you. I would ask you not bring a computer either (you can't really 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 Facebook.

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:
  • Some of the conventions and methods of philosophy (that is, how philosophers use logic as their primary method);
  • 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.