Critical Thinking and Bias in Science

Learning Objectives

Define critical thinking.

Identify different types of bias that can affect scientific investigation (e.g., confirmation bias, sampling bias).

Explain the importance of skepticism and peer review in science.

Distinguish between observation and inference.

Thinking Like a Scientist

Science is more than just facts and experiments; it's a way of thinking. Critical thinking is the objective analysis and evaluation of an issue in order to form a judgment. It's about asking questions, examining evidence, and not just accepting things at face value.

Observation vs. Inference

A key part of scientific thinking is separating what you see from what you think it means.

Observation: Information gathered directly using your five senses or scientific instruments. It is a statement of fact.

Example: "The liquid in the beaker turned blue."

Inference: An explanation or interpretation of an observation. It is a conclusion based on evidence and reasoning, but it is not a direct observation itself.

Example: "A chemical reaction occurred, forming a new blue substance."

The Problem of Bias

Scientists are human, and they can be influenced by their own beliefs and expectations. Bias is a prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair. Bias can lead to flawed experimental results and incorrect conclusions.

Confirmation Bias: The tendency to search for, interpret, favor, and recall information in a way that confirms one's pre-existing beliefs or hypotheses. A scientist might unconsciously pay more attention to the data that supports their hypothesis and ignore the data that contradicts it.

Sampling Bias: Occurs when the sample used in a study is not representative of the larger population. For example, testing a new drug only on young, healthy men would create a sampling bias, as the results might not apply to women, children, or the elderly.

How Science Reduces Bias

The process of science has built-in mechanisms to help reduce the effects of bias.

Skepticism: Good science involves a healthy dose of skepticism. Scientists question their own results and the results of others, always looking for alternative explanations.

Repeatability: An experiment is not considered valid unless other, independent scientists can repeat it and get the same results.

Peer Review: Before a scientific study is published in a reputable journal, it is sent to other anonymous experts (peers) in the same field. These reviewers check the methods, data, and conclusions for any flaws or biases. This process acts as a quality control filter for science.

Key Terms

Critical Thinking: The objective analysis and evaluation of facts to form a judgment.
Bias: A tendency or prejudice that prevents impartial consideration of a question.
Confirmation Bias: The tendency to favor information that confirms existing beliefs or hypotheses.
Peer Review: The evaluation of scientific work by others working in the same field to ensure it meets necessary standards before it is published.
Inference: A conclusion reached on the basis of evidence and reasoning.