Critical Thinking and the Tools of Reason
Critical thinking aims to help you decide whether you should believe
some claim, or even perhaps just consider it probable, or even just
possible. In general, we encounter claims from four kinds of sources:
Philosophers are most concerned with arguments and theories.
- Conclusions of arguments
- Products of theories
Philosophers are least concerned with this. But, reports should be
evaluated in terms of the reliability of the source, and any biases
it may have.
Observations need to meet either standards of good evidence (such as
protection against potential bias) and also may be questioned in terms
of the deepest epistemic issues.
There are three kinds that we need to be concerned with
- Deductive. Deductive arguments are measured in terms of
whether they are valid. A valid argument is an argument where,
if the premises are true, the conclusion must be true.
- Inductive. Inductive arguments generalize from some
finite number of observations to an indefinite further group of
potential observations. Inductive arguments generally are evaluated
using standards of scientific reasoning.
- Abductive. Sometimes we have a set of explanations before
us for a phenomenon, and so we pick the best one. This is abductive
Sometimes we conclude something because it is consistent with or
predicted by a theory. There is not complete agreement on how we
evaluate theories, but a few criteria are widely considered important.
These include, in order of importance:
Predictive power is best. However, some theories, such as
mathematical theories, do not predict phenomena but rather describe
them. We tend to evaluate those theories in terms of how much they
explain. (Note that we could drop the first criterion, since rampantly
inconsistent theories will have no predictive or explanatory power
because they will rule no prediction or explanation out.)
- Internal consistency.
- For scientific theories or other theories that
describe the natural world: predictive power. For
other kinds of theories: explanatory power.
- Consistency with other existing theories.
Other Philosophical Tools
Along with primarily evaluate arguments and theories, philosophers are
also often engaged in conceptual clarification. This is often very
important, and leads to breakthroughs. (Similar kinds of
clarification occur in mathematics, it is worth noting.)