Data on teaching or examination

405384, Specialization: Philosophy of Science (FTE345d)What if? A guide to reasoning with counterfactual scenarios, 3 cr
Code 405384 Languages of instruction English
Name Specialization: Philosophy of Science (FTE345d)What if? A guide to reasoning with counterfactual scenarios Abbreviation FTE345d 
Scope 3 cr  Unit Theoretical Philosophy 
Form of study Seminar  Grading General scale 
Date 16.03.2017 -27.04.2017 Additional data  
Teaching designed for
Data was last edited 05.06.2019

Target group 

What if? A guide to reasoning with counterfactual scenarios

Graduate and master's students.


The lectures will be self contained, but having attended an introductory logic course is a prerequisite. Having attended a course on modal logic is an asset.


Through the course, the student will learn the main interpretations of counterfactuals and a method for constructing an inferential system for reasoning with counterfactuals. The course will also give a chance to practice and develop presentation skills.


Over the centuries, logic has developed precise methods that guide us in hypothetical reasoning: if we assume that certain things are true, then we can conclude that also some other things are true. But what if our assumptions are false, and we want to draw conclusions from assuming their truth, and this assumption is contrary to the present evidence but is nevertheless conceivable in some scenario alternative to the current state of affairs?

The basic element of such forms of reasoning is given by what is known as counterfactual conditionals, an if-then sentence in which the if-clause may or may not be true. Counterfactual conditionals occur all the time in everyday language in sentences such as "If Helsinki were not the capital of Finland, then Turku would be'', or "If Finland had not won the 1995 Ice Hockey World Championship then Sweden would have".

As shown by a series of fallacies, counterfactual conditionals escape a straightforward logical analysis based on the standard notion of implication. Difficulties in such analysis arise from the fact that such conditionals are not immediately truth-functional for the reason that in counterfactual scenarios, truth becomes a relative notion.

Many attempts have been made in the literature to capture the meaning of such conditionals and eventually develop a formal logical analysis as precise as the one achieved for the standard conditional of classical logic. Among these, we shall analyse in detail the approach developed by David Lewis in his book "Counterfactuals," based on a relation that orders possible worlds with respect to their similarity to the actual world. This sophisticated semantical analysis has not been accompanied by an equally developed proof-theoretical investigation of logical formalisms for reasoning with conditionals which latter have been limited, apart from isolated attempts, to axiomatic systems.

After reviewing Lewis' and other semantic approaches, we shall develop a formal method for reasoning with conditionals based on an abstract neighborhood semantics, a generalization of Kripke semantics. We shall establish its adequacy, completeness, and inferential properties, as well as a decision procedure.


The lectures will be accompanied by project-based presentations held by the participants and based on recent literature on conditionals. Depending on the number of participants,  projects will be either individual or in small groups. Specific topics will be agreed upon with the instructor from a list of suggestions and will be based on recent research articles and/or monograph chapters. A successful project will demonstrate the ability to locate relevant literature, summarise its content, highlight the existing challenges, and apply the methods learnt during the course. The findings will be detailed in a paper of max.15 pages. Presentations of the papers will be scheduled at the end of the course and will be open to the whole class for discussion. A minimum of 80% attendance is required; absences should be limited to exceptional cases. Alternatively, a more traditional written exam will be arranged.

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Registration period
Seminar  Teacher Date and location
Reg. period has ended 05.01.17 klo 23.50-
16.03.17 klo 10.05
Reg. Cancel No.
Specialization: Philosophy of Science (FTE345d)What if? A guide to reasoning with counterfactual scenarios Sara Negri
    thu 10.15-11.45,