Necessary, But Not Sufficient . .

thought categories 2 Categories of Thought

One of the categories of thought we delineated was “Related To, But Not Synonymous With.”  That is, at times we can develop an idea by pointing out that it is “related to, but it is not synonymous with.”

Another category of thought is  — “Necessary, But Not Sufficient”*

This is another category of thought which has rhetorical value.  While working on your speech or message (or after you have worked on it), you may want to . . . . .

  • add content
  • clarify
  • expand on
  • develop
  • illustrate
  • magnify
  • change-it-up
  • modify
  • introduce**
  • add variety to
  • conclude
  • explain

. . . . a point, your message, or a portion of your message/speech.

By using this category of thought, you can help accomplish one or more of these various aims.

To effectively do this, you have to consciously understand this category of thought and how this category of thought works.

Let me illustrate this thought pattern in a simple way and then move to how it works with a biblical truth or principle.

Secular Example:

Rootbeer is necessary to make a Rootbeer float, but it is not sufficient.

It takes more than Rootbeer soda.

Rootbeer is necessary but not sufficient.

Ice cream is necessary but is not sufficient.

It takes both – Rootbeer and Ice Cream.

The point being made is that — Both parts are necessary, but neither is enough in and of itself.  Any single element is necessary, but neither one is sufficient.

Biblical Examples:

Knowing Who Christ is, His death on Calvary, and His resurrection is necessary to become a Christian, but it is not sufficient.

It takes more than knowing.

Knowing Who Christ is necessary but is not sufficient.

Knowing about His work is necessary but is not sufficient.

Knowing about His resurrection is necessary but is not sufficient.

It takes both knowing and acting on that knowledge.

The sacrificial system was necessary to the purifying of the flesh, but was not sufficient to take away sins (Hebrews 9:13; 10:4).

Praying is necessary to being a spiritually minded person, but it is not sufficient.  Prayer alone is not all there is to being spiritually minded.

Sharing the Gospel is necessary to the salvation of others, but it is not sufficient.  It takes more than sharing the Gospel.  It does take that (Faith cometh by hearing the Word), but it also takes the work of the Spirit of God.


We could multiply such biblical examples where X is necessary, but X is not sufficient.  This category of thought has value in that it helps speakers and preacher think through issues. It helps promote clarity and sound logic.

But it also provides a mind generating thought pattern which can be consciously employed to develop part of a speech or message.  If I wanted to clarify an idea, a truth, a principle, a point, etc. I could mentally run with this “topos.”

Let me provide an example of how it can generate content . . . . Here goes . . . . Off the cuff, I am going to generate message content using this “topos.”

There will be those who minimize the role of making good and right choices.   You will hear them say —

Doing this-or-that doesn’t mean that . . .

That-or-that doesn’t make you . . .

In no way does this-or-that mean that one is spiritual or godly.

You can still love God and serve Him even if you don’t . . . .

No — “this-or-that” is not sufficient to produce godliness.  It does not have the power or strength to accomplish this-or-that desired spiritual goal alone. . . . .

No . . .

Attending church doesn’t have the power to make you spiritual.

Avoiding the amusements which excite the flesh will not alone result in a holy life and godly living.  It is not sufficient to accomplish that . . . . . . . .

But attending church is necessary if we identify ourselves as believers in Christ.  He died for His church — the church which is that group of believers who fellowshipped together –  and remembered Him by breaking bread together – and were challenged to live a godly life by gifted men who preached the Word, in season and out of season! Such isn’t sufficient, but it is necessary. . . .

— Ted Martens




It says — Add to your faith (II Peter 1:5) — because there is no single “addition” that alone is sufficient to produce a godly life.

The Christian life is not defined by any one element.

Your Christian life and your maturity may be marked

by prayer

or by sharing the Gospel

or by Bible reading

or by freedom from some of the vices others are plagued with

or by faithful church attendance

or – or – or

However, the Christian life is not one area.  Just because we have that one area down — pretty good does not mean we are godly.  We are like God – godly – in that area, but there is more to our Christian lives.

No one area is sufficient, but they are all necessary parts of godly living.  We need to be on a trajectory towards being more and more Christlike in regards to the many areas of “addition.”

— Ted Martens



When you work on a speech or a message, keep in mind the concept — “Necessary, but not sufficient” and/or “Not sufficient, but still necessary.”  It may . . . .

help you develop a part of your message.

clear up some confusion that the audience has had in regards to . . . .

drive the point or argument you are making.

help you design an introduction or conclusion.

* “Given two conditions X and Y, there are four ways in which they might be related to each other:

  1. X is necessary but not sufficient for Y.
  2. X is sufficient but not necessary for Y.
  3. X is both necessary and sufficient for Y. (or “jointly necessary and sufficient”)
  4. X is neither necessary nor sufficient for Y.

This classification is very useful in when we want to clarify how two concepts are related to each other. Here are some examples :

  • Having four sides is necessary but not sufficient for being a square (since a rectangle has four sides but it is not a square).
  • Having a son is sufficient but not necessary for being a parent (a parent can have only one daughter).
  • Being an unmarried man is both necessary and sufficient for being a bachelor.
  • Being a tall person is neither necessary nor sufficient for being a successful person.”


Other Examples:

An “A” is NOT necessary to pass the course, but it is sufficient.

An “A, B, C, or D” sufficient to pass the course, and is also necessary.

Passing the test is necessary to complete the class, but is NOT sufficient.  You must do more than pass the test.  You must also attend, participate, and write a paper.

Just building one’s strength will not make you a competitive weight-lifter  It is not sufficient, in and of itself, but that does not mean it is not necessary.


** Used As An Introduction

“In mathematics and philosophy, we show something to be true if it meets criteria that are both necessary and sufficient. For example, for an object to be a square, it must have four sides. But while a necessary condition is that the object have four sides, this condition is not sufficient because a rectangle also has four sides.

On the other hand, some conditions are sufficient but not always necessary. For instance, in school, a student who earns an A is guaranteed to pass the course. In other words, an A is a sufficient condition for passing the course, but it isn’t necessary because a student who earns a B or a C will also pass the course.

To prove something to be true, like the square, we sometimes need a multitude of necessary conditions that together become sufficient. That is, all conditions must be met at once for the answer to be true. In this example, a square must have four sides, all straight, all equal length, joined at the ends, lying in a plane, with four 90-degree angles, etc. If we meet all these criteria, then, and only then, are we guaranteed a square.

Necessary and sufficient.

The Levitical sacrifices were not sufficient, but they were necessary because God required them. Under the Mosaic Law, a different type of sacrifice was brought for each sin, and each time a sin was committed, a new sacrifice had to be offered. Though the priests offered many different sacrifices to atone for the many different sins, still, no sacrifice was ever sufficient. The priests themselves were sinful and could never offer complete redemption.

Jesus offered one sacrifice for all our sin. Rather than many, repeated sacrifices, his was once for all. Rather than different requirements to cover the guilt of different sins, his sacrifice paid for all sins.”


One thought on “Necessary, But Not Sufficient . .

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.