Critical Thinking Note 24: Critical Thinking Basics

Twenty four notes into this series, it has been a while since we’ve laid out the basics. So, time for another pass. Critical Thinking is basically about getting at truths and avoiding falsehoods as best we can. So how do we tell if a proposition is true? The simple answer is to examine the evidence and the reasoning based on the evidence. Reasons are arguments and we have pretty well developed methods for formulating, clarifying and evaluating these. This is what logic is all about.

Arguments have some basic parts, premises and a conclusion to be specific. To determine whether an argument provides a good reason for accepting its conclusion as true we need to do two things (and only two things, trying to do other things leads us into the realm of fallacies, mistakes in reasoning).

The two steps involved in evaluating an argument are as follows:

  • Determine if the premises are true
  • Determine whether the premises support the conclusion

Determining whether the premise of an argument are true may involve evaluating some evidence or it may involve evaluating further arguments. While this may sound pretty straightforward and manageable, getting at the truth of a matter can be an involved process and sometimes our best efforts aren’t entirely conclusive. Critical thinking methods are the best tools we have, but like any good tool, there will be limits to what you can achieve with them. Fortunately, the limits are soft in the sense that with more skill and better evidence we can achieve progressively more in the way of getting at the truth. But we should not expect even the best tools and strongest skills to lead to successful acquisition of knowledge in every instance. Part of being human is coping with our own imperfection and limitations.

There are two standards we can appeal to in evaluating whether the premises of an argument provide logical support for its conclusion. There is the sure fire standard of deductive validity and the pretty good standard of inductive strength. Here are the basic definitions of these two standards:

  • A deductively valid argument is one where the conclusion must be true if the premises are all true.
  • An inductively strong argument is one where the conclusion is likely to be true if the premises are all true.

The science of deductive validity is precise, formal and pretty well developed. We teach the basics of this science, including formal methods for proving the validity of valid arguments, in PHIL& 120, Introduction to Logic. The fact that this course is not as standard a part of our educational curriculum as basic algebra continues to baffle me. Our world would be a far different place if it were.

Inductive strength is messier than formal deductive logic. There are assorted patterns of argument that aim at inductive strength and each admits of varying methods of evaluation. Unlike deductive validity, inductive strength admits of degrees. Partly because of this, the methods for evaluating inductive argument are often less precise than we’d like. And yet we can cultivate high levels of skill at evaluating inductive argument and the successes of science are testament to this. PHIL& 115 Critical Thinking includes substantial focus on how to evaluate inductive argument.

Our students get precious little dedicated instruction in how to reason well. Students get even less instruction on how to recognize good reasons. What spotty instruction they do receive often focuses on identifying fallacies, or mistakes in reasoning. This is good stuff, and the most thorough investigation of fallacies at BC will also be found in PHIL& 115, Critical Thinking. But when students learn about a few fallacies without the benefit of developing skill at appreciating good reasoning, they often fall into the trap I call the fallacy fallacy, the notion that every argument is fallacious (and especially if you don’t like the conclusion). Spotty instruction in critical thinking that focuses mainly on spotting fallacies is liable to facilitate distrust and unhealthy, cynical skepticism. It is vitally important that students get good training in how to reason well and recognize good reasons.

There is no substitute for focused dedicated training in how to reason well. It remains an open chasm in our curriculum. Every student in the US receives a decade and then some of instruction in how to reason with numbers and only occasional and passing attention to how to reason more generally. The results of this experiment are now manifest. The ongoing degradation of our natural environment, information environment and social institutions, in short the very conditions for human flourishing, would hardly be possible except for our twin failures of critical thinking and love. These twins are conjoined. Arrogance, prejudice and hatred are the end results of inattention and sloppy, self-serving thinking. Compassion and understanding and knowledge are the fruits of active, clear and open inquiry. Critical thinking is at the heart of this.