What is Boolean search logic?

To effectively conduct a Boolean search, it helps to first understand Boolean logic. While it may sound exotic or mythical, Boolean logic was simply named after the man who developed it, George Boole. A 19th-century English mathematician and logician, Boole initially intended to provide a foundation for and extend the applicability of Aristotelian logic. Boole did this by putting formal logic into mathematical form. He believed that every piece of variable data could be fit into one of two categories: “true” or “false,” with nothing in the middle.

Here’s an everyday example: I want a cold drink. Here, “cold drink” can be the first variable in an equation: “If I can purchase a cold drink, then I will go to the tavern.” As long as the tavern sells drinks that are not hot, you have a variety of drink options to choose from. Now, because I am tired, the drink must also contain caffeine.

“Caffeine” becomes a second variable in this equation: “IF (cold drink) AND (caffeine), then I will buy a drink at the tavern.” If both of these are true, then the output is true, meaning I will go to the tavern and buy a drink. But if even one of these is false (the tavern doesn’t sell caffeinated drinks or they don’t have cold drinks because their ice machine is broken), then the total output is false. I may be curious about the tavern, but I will go somewhere else for a cold, caffeinated beverage.

Boolean logic can become infinitely more complicated to produce a specific result. You see it daily at your favourite café: “I’d like an iced, dairy-free latte with a double shot of espresso.” The combination of these variables “iced” AND “dairy-free” AND “latte” AND “double shot of espresso” produces the true result. If one of these variables is false, say, the barista uses dairy milk, I don’t want the drink and won’t pay for it. All conditions must be met for a “true” result.

That’s helpful for the café, but how does this extend to the internet?

What is a Boolean search?

The Boolean Search simply takes the café example and extends its principles to any internet search. It’s something you already do. For example, if you want to learn more about the foreign policy of Thomas Jefferson’s presidency, you would type in quotes specific words such as “Thomas Jefferson’s presidency foreign policy.” This filters out information about Jefferson writing the Declaration of Independence, founding the University of Virginia, or building Monticello. A Boolean search saves you time by adding specificity and context to your search. It weeds out irrelevant information and focuses on results that have been preliminarily vetted by the search engine itself.

Boolean search recruiting

For these reasons, Boolean search is incredibly popular in the hiring search. Who doesn’t want help in pinpointing the right candidates for a position? First, decide exactly what requirements are the most important to you in a candidate. Then, use a combination of modifiers to organize content.

Say, for example, you have a position to fill in the billing department of your health care office. You want someone familiar with all the insurance codes. Therefore, you would type “billing AND insurance” to find candidates whose resumes reflect that experience. Instead of sifting through hundreds of resumes, a Boolean search can cut out those who don’t have billing experience with insurance companies. As a result, someone who has done billing for a private tutoring service won’t come up in your search. Imagine the time you’ll save. A Boolean search produces consistent results every time.

This search technique works wonders when using Indeed Smart Sourcing. Indeed’s Resume search page allows you to filter various keywords to help you narrow down your search results and locate candidates who closely match your job’s criteria. You can use keywords and operators to effectively refine your search. 

After your initial search for a job title and location, use the left-hand sidebar to filter the results further. This can help you streamline and expedite the process of finding suitable candidates even more.

Related: 10 Recruiting Strategies for Hiring Great Employees

Boolean search terms

A Boolean search is straightforward, combining keywords with operators to achieve the outcome. You can repeat and combine these elements.

Keywords

Keywords in a Boolean search can include position names, skills, education, location, years of experience, and more. For example, a basic keyword when hiring an HR manager would be “human resources.” By itself, “human resources” is not a Boolean search, but it is a strong first building block.

The Three Operators: AND, OR, and NOT

Adding AND to combine your primary keyword with another is a classic Boolean search. AND tells the search engine that any result must contain both of these keywords to be a true or relevant search result. In the above example, you could search for the keywords “human resources AND office administrator” if you want a candidate who has experience in both of those areas. A candidate with only “human resources” experience would not show up in your search, because your search is now more specialized.

The operator OR is a Boolean search tool that tells the search engine that a candidate with either of the keywords is a viable option. Recruiters usually use the OR modifier to cast a wider net, listing different versions of a similar term. This way, they won’t miss any qualified candidates. For example, searching either “human resources manager OR HR manager” would yield applicants who listed their experience either way. Not everyone describes their experience in the same way.

NOT is the Boolean operator that tells the search engine what type of result to exclude. List keywords you are looking for, then NOT, then keywords you don’t want. For example, “HR manager NOT HR director” would bring up all candidates with HR managing experience, but not those with experience as an HR director. If a person had experience as both a manager and director in HR, they would no longer be considered a true candidate, because true candidates only have experience as an HR manager.

Parentheses and brackets

Just as in math equations, the way you group key terms in parentheses and brackets is important. These are used in advanced Boolean searches. The search engine resolves keywords and operations inside the parentheses first. For example, “(human resources) AND (recruiter OR hiring manager)” delivers different results from “(human resources AND recruiter) OR (hiring manager)” due to the placement of the parentheses. The first Boolean search tells the search engine to find applicants with experience in human resources and in either recruiting or hiring. The second Boolean search delivers applicants with experience in both human resources and recruiting or experience just as a hiring manager.

Quotation marks

Quotation marks tell the search engine that multiple keywords must be searched together. Multiple keywords with no quotation marks can yield applicants who happen to mention those words in their document. This can have unintended effects. For example, if an applicant wrote in their cover letter, “I don’t know much about hiring, but I’d make a great manager,” they could pop up on a search for “hiring manager” if the words “hiring” and “manager” were not grouped together within quotation marks. Yet “hiring manager” in quotation marks excludes these unqualified candidates because the search engine sees that you are seeking the title as a whole, not just individual words.

How to do a Boolean search (with examples)

Use these strategies in your Boolean search for job candidates:

Use capital letters

When writing the conjunction or modifying word in capital letters, the search engine grasps that you are performing a Boolean search. Many websites eliminate conjunctions in a search, but if they are capitalized, they are recognized as part of a Boolean search. For example, “human resources and hiring manager” could yield results with just one of those terms. However, “human resources AND hiring manager” means that both of those titles must be present to be considered true.

Carefully analyse punctuation

Be meticulous with quotations and parentheses. Misplaced punctuation can sabotage your search. When you open a quotation or parenthesis, don’t forget to close it.

For example, this search term is missing quotation marks and parentheses:

((Graphic design OR graphic designer) OR (digital artist OR digital art) AND ((photoshop AND InDesign) NOT “entry-level job OR beginner)

This means the search engine won’t group these terms correctly.

Here is the correct version:

((Graphic design OR graphic designer) OR (digital artist OR digital art)) AND ((photoshop AND InDesign) NOT (“entry-level job” OR beginner))

Try different phrasing

Remember, the OR operator describes a similar experience in different ways to cast a larger net. For example, search “I graduated from” OR “college graduate” OR “bachelor’s degree” to find candidates who completed their degrees. By using all three descriptions, the search engine will yield more qualified applicants.

Related: How to Search for Qualified Candidates on Indeed Smart Sourcing

Frequently asked questions about Boolean searches

What is a Boolean phrase?

A Boolean phrase is any set of keywords combined with operators used to describe desired variables or outcomes.

What are the three Boolean operators in a search?

Search engines recognize the operators AND, OR, and NOT as creating a Boolean search.

Why are Boolean operators important?

Boolean operators tell a search engine how to interpret the desired keywords.

What is an example of a Boolean search?

One example is “(forklift operator) AND warehouse.”