Inductive vs. deductive reasoning

You probably ended up on this page because you came across the terms "inductive and deductive reasoning" somewhere. Inductive reasoning works differently than deductive reasoning. In inductive reasoning you aim to arrive at a new theory based on data, while in deductive reasoning you build on a theory that already exists and begin testing it. What exactly is the difference between inductive and deductive reasoning? How do you properly execute both types?

Inductive research involves building a theory based on data you collect yourself. You often choose this approach because there is little existing literature on your research topic.

In deductive research, you rely on an existing theory and proceed to test it. You often use this type of research when several theories already exist about your research topic. You can then test one or more of them. 

You can also combine these two approaches in one study.

Inductive reasoning is also called "bottom-up" reasoning. This is because you begin your project without an overarching theory, and instead start by collecting data in order to try and find your own pattern in it. That way, you can arrive at a theory or hypothesis from your own results. 

This has the advantage of allowing you to build a new theory from the data on a topic for which little literature exists. 

A possible limitation of this line of reasoning is that the patterns you find in your data cannot always be generalized to all cases. Your conclusion is always an educated guess. Of course, your conclusion is better substantiated if you conduct research among a larger group because the results are then more representative.

Example of inductive reasoning

For example, inductive reasoning can look like this:

1. You make an observation that inspires you to research something. For example, "In Amsterdam I know a lot of young people who smoke, more than in Rotterdam."

2. You are going to collect data to investigate whether a pattern can be found in this observation. For example, you decide to survey 300 Amsterdam youths and 300 Rotterdam youths.

3. You try to establish patterns in the data. It turns out that 15% of Amsterdam youth smoke, compared to 10% of Rotterdam youth. So, the percentage is higher in Amsterdam than in Rotterdam.

4. From this data, you formulate a theory: "More young people smoke in Amsterdam than in Rotterdam."

Of course, as mentioned, this is an estimate. For example, the neighborhoods in Rotterdam and Amsterdam you are researching or the age of young people in your study may matter to your findings. More research is probably needed to make certain statements about this, but your theory is still a good starting point for further research. 

If you were to do this research among 10,000 Amsterdam and 10,000 Rotterdam youths, you would already be able to draw your conclusion with more certainty. 

In deductive reasoning, you proceed top-down. You start with an overarching theory and test it against concrete data. The generalization is already there, and you start looking for concrete evidence to confirm or reject the theory or hypotheses. 

For deductive inquiry, you do need a theory. If one doesn't exist, you have nothing to build on. Deductive research is therefore most common in topics that have already been the subject of existing research. You then refer to previous research in the theoretical framework, and come up with hypotheses for your research based on that.

It often occurs that several theories already exist in the field of your topic. You discuss these theories in the theoretical framework and then come up with your own hypothesis based on one or more of those theories. You often test that hypothesis with an experiment, quantitative surveys, or other quantitative research.

In deductive reasoning, it is especially important that your research is valid. So take extra caution to make sure you measure what you want to measure. To do this, you need to operationalize the variables correctly. 

Example of deductive reasoning

In deductive reasoning, you often go through the following steps:

1. You choose a theory you want to test. For example, you've come across this theory somewhere that "The percentage of Amsterdam youths smoking is higher than the percentage of youths smoking in other Dutch cities.” You question the existing research done to prove this theory.

2. You formulate a hypothesis to test this theory with your own data. Your hypothesis reads "The percentage of young people who smoke is higher in Amsterdam than in the seven other largest cities in the Netherlands.

3. You will collect data according to the chosen research method to test the hypothesis. You will conduct surveys in these eight cities among 50 young people in each city, asking questions about their smoking behavior, among other things.

4. Based on the results, you will confirm or reject the hypothesis. It turns out that the percentage of young people smoking is higher in Rotterdam and The Hague than in Amsterdam. You therefore reject the hypothesis.

Sometimes the proper approach becomes readily apparent from your research question or from previous literature you may or may not have been able to find. 

If you are still unsure whether inductive reasoning or deductive reasoning is more appropriate for your research, this checklist may help you:

• Is there little literature on your topic? Then you often should do inductive research.

• Is there a lot of existing literature? Then deductive research is more appropriate.

• Do you want to test an existing theory or hypothesis? Then you need deductive research. 

• Does no theory exist yet, or do you want to create a new theory? Then inductive research is the right approach.

• Are you researching a past situation? Then, you often do deductive research (you base your research on a previous theory and possibly build on pre-existing data).

• Do you want to make predictions about the future? Then inductive research is often more appropriate.

Beautiful! You are in luck. We've written several articles about this. For example, in our knowledge base, you can read more about:

• What research methods exist;

• How to choose the right research approach;

• How to assess the quality of your research;

• reliability and validity;

• reproducibility and replicability;

• the method chapter in your thesis. 

We also go into detail about the research plan, research design, surveys and interviews, among other things. This will allow you to learn about your options and then make the right choices about how to conduct your thesis research. Start reading now!