The SEX Theorem of Hiring

Software engineers are likely familiar with the CAP theorem, coined by Eric Brewer. In essence, the CAP theorem states that distributed databases can have at most 2 of 3 attributes: consistency, availability, or partition tolerance (fault tolerance).

In other words, you can have a database that is consistent and highly available, but not fault tolerant. Or, you can have one that’s fault tolerant and highly available, but isn’t always consistent (especially during network failures).

It’s an elegant concept that has withstood the test of time—nobody has yet created a distributed database that truly possesses all three properties, despite what some enterprise software vendors might claim.

I’ve observed that a similar principle applies when hiring engineers. When recruiting technical talent, you’ll have to choose candidates who possess at most 2 of these 3 attributes:

• Being highly Skilled
• Being highly Experienced
• Being ineXpensive

I call this the “SEX Theorem of Hiring Engineers.”

This theorem creates three distinct profiles of engineering candidates:

The SE (Skilled + Experienced) #

These are your “10x engineers” (a term I use reluctantly). They bring deep technical expertise combined with battle-tested experience. They’ve seen systems fail in surprising ways, have built complex architectures that scale, and can spot potential issues before they become problems. An SE might be able to solve in an afternoon what would take a junior team a week, and their solutions will be more elegant and future-proof.

SEs command premium compensation because they deliver premium value. They won’t accept startup equity in lieu of competitive salary because they understand probability and won’t subsidize your venture-backed startup with their below-market wages. However, they do expect meaningful equity because they want skin in the game and understand the value they bring.

The SX (Skilled + inexpensive) #

Typically a younger person with natural talent—perhaps a recent graduate or even a dropout. While they lack experience, they bring fresh perspective, cutting-edge knowledge of newer technologies, and boundless enthusiasm. For them, your job represents a significant opportunity for growth.

The best SXs are quick learners who can rapidly close their experience gap. They might have impressive GitHub repositories, contest wins, or side projects that demonstrate their raw talent. They’re often worth taking a chance on, especially when paired with mentors who can help them develop.

The EX (Experienced + inexpensive) #

Potentially the most problematic hire. Their resume might be decorated with impressive company names and extensive years of service, but their actual contributions have been minimal. They’ve mastered the art of interviewing and corporate politics, but rarely deliver meaningful technical work.

The EX can speak eloquently about architectural patterns and process methodologies, yet struggle when asked to implement anything complex themselves. They remain inexpensive because their market value aligns with their actual (rather than claimed) capabilities. Some might make competent managers, but they’re rarely effective technical contributors.

Hiring Implications #

Many VC-funded startups inadvertently optimize for a mix of SXs and EXs. They hire SXs because venture capitalists often implicitly impose salary constraints on portfolio companies by hinting that high wage expenditures will make follow-on funding difficult. They hire EXs because these candidates interview well or have prestigious credentials that look good to investors.

As a job seeker, companies making lowball offers should raise red flags. If they’re underpaying you, they’re likely underpaying everyone else as well, which means they probably aren’t attracting top talent. When recruiters counter salary negotiations with “we have free snacks and unlimited PTO,” remember that these perks don’t pay your mortgage or student loans.

The optimal engineering team consists primarily of SEs, with some promising SXs for growth potential. This balance creates a culture of excellence where knowledge transfer happens naturally and technical standards remain high. However, this approach requires a significant investment and commitment to competitive compensation.

Problems arise when organizations accumulate too many EXs, especially in leadership positions. EXs and SEs mix like oil and water—the former attempt to manage the latter through process and bureaucracy, while SEs value competence and results over politics. A heavy concentration of EXs and SXs often leads to technical debt, missed deadlines, and eventual product failure.

For founders concerned about preserving their culture, prioritize hiring SEs whenever possible, even if it means a higher burn rate. Your investors might question the expense initially, but they’ll appreciate the results later. Remember that hiring SEs becomes easier once you already have some—they recognize each other’s abilities and prefer working alongside peers of similar caliber.

SEs also make excellent mentors for promising SXs. This pairing allows SXs to develop the experience they lack, potentially transforming them into SEs. However, be prepared to adjust compensation accordingly as they grow, or risk losing your investment to competitors willing to pay for their newly developed expertise.

Finally, the mythical “SEX engineer”—someone who is simultaneously skilled, experienced, and inexpensive—simply doesn’t exist in today’s market. If you believe you’ve found one, you’ve either discovered a unicorn or (more likely) misjudged one of these attributes. And even if you somehow convince an SE to accept below-market compensation temporarily, they won’t remain for long once they realize their true value.

In a competitive landscape where technical talent drives success, understanding the SEX theorem helps you make more informed hiring decisions. Choose wisely—your company’s future may depend on it.